Vancouver Aquarium Resource Guide

Background Information for Teachers on our Animals and Ecosystems

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Contents

Welcome .......................................................................................... 3

The Vancouver Aquarium .................................................................... 4

Ecosystems ....................................................................................... 5

Introduction to Ecology .................................................................... 5

Amazon Ecosystem ......................................................................... 6

Arctic Ecosystem ............................................................................. 8

North Pacific Ecosystem ................................................................. 10

Tropical Reef Ecosystem ................................................................ 13

The Intertidal Zone ....................................................................... 14

Classification ................................................................................... 17

Marine Invertebrates ........................................................................ 19

Phylum Porifera ............................................................................ 20

Phylum Cnidaria ............................................................................ 21

Phylum Mollusca ........................................................................... 24

Phylum Arthropoda ....................................................................... 27

Phylum Enchinodermata ................................................................ 29

Phylum Chordata .......................................................................... 31

Phylum Platyhelminthes ................................................................. 32

Phylum Nemertea ......................................................................... 33

Phylum Annelida ........................................................................... 34

Marine Invertebrates: Summary ..................................................... 36

Fishes ............................................................................................ 38

Adaptations for Survival ................................................................. 38

Major Groups of Fishes .................................................................. 45

Adaptations of Cartilaginous Fishes ................................................. 46

Adaptations of Bony Fishes............................................................. 48

Marine Mammals ............................................................................. 52

Marine Mammal Adaptations ........................................................... 53

Cetaceans .................................................................................... 55

Cetacean Adaptations .................................................................... 57

Marine Mammal Orders .................................................................. 62

Staying Alive: Survival Adaptations .................................................... 67

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Welcome Welcome to our Vancouver Aquarium Resource Guide!

The aim of this guide is to support Teachers, Educators and students alike in

their journey of discovery about marine ecosystems and marine animals with an ultimate goal of conservation in action.

Research shows that in order to maximize not only the success of your

students during their Aquarium visit, but the richness of their experience as

a whole: there needs to be pre and post visit lessons relating to the content and themes at hand.

The content provided in this guide is designed to…

be used as a resource when planning your lessons—pick and choose the animals you want to introduce to your students, and dive in!

make you confident and comfortable when answering inquiries posed by keen young minds.

support you and your students in getting the most from your Aquarium visit.

be flexible - feel free to use this information ‗as is‘ for reading activities for students where appropriate.

The contents page will assist you in finding the information that you desire.

Please print only the pages you need and consider our environment – you

can select specific page numbers to print in the print function. Remember to choose the double-sided printing option too!

You will come across links to online Aquarium resources throughout this

document; simply hold the Ctrl key and click on this text to access the link.

Lastly, this document is not designed to be static; we‘d like to make it as user friendly, up-to-date, adaptable and informative as possible. It is a

document that is living; constantly growing and evolving. This is where we need your help! Please e-mail us with feedback, wish-list items, suggestions

and more. With your guidance, we can support you in enriching your lessons and building understanding and connections in your classroom.

Best fishes,

The School Program Team education@vanaqua.org

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The Vancouver Aquarium

The Vancouver Aquarium Marine Science Centre is a self-supporting, non-

profit association dedicated to effecting the conservation of aquatic life through display and interpretation, education, research, and direct action.

The links below provide extensive background information, from our

AquaFacts online, on a variety of topics that relate to the Aquarium.

Why do we have aquariums?

What is the history of the Vancouver Aquarium? Who works at the Aquarium?

How many animals do we have at the Aquarium? Where does the Aquarium get all that water?

What do we feed the animals, and where do we get their food? Where do we get the animals?

Careers

Career as a Marine Biologist Career as a Marine Mammal Trainer Career as a Whale Biologist or Researcher

Get involved!

There are lots of ways to get involved with the Aquarium‘s wide array of

Education, Conservation and Research Programs.

Volunteer and Work Experience

Sleepovers, AquaVan, School Programs and more… Great Canadian Shoreline Cleanup, Adopt an Orca and more…

Learn about our Research Programs

Planning your trip to the Aquarium

Vancouver Aquarium staff highly recommend you check out our Visitor

Information online to plan around our daily events schedule, hours of

operation, amenities, and more.

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Ecosystems

Introduction to Ecology

Organisms living on earth do not exist independently but are influenced by their environment. They live together.

Ecology is the study of the relationships between organisms and their

environment. The present diversity of organisms is the result of the interplay between environment and adaptation.

Environment: All of the physical, chemical, and biological factors in the

area where a plant or animal lives.

Adaptation: Each animal species, by the very fact that it has existed for some time, must have evolved adequate means of surviving in its particular

habitat. The adaptations of an animal cannot be interpreted except in relation to the environment with which it interacts.

An animal must be able to adapt in two different ways to its environment: First, the animal must be adapted to live in a biotope defined by such

environmental factors as temperature, moisture, water, height, depth, etc. This is the habitat. Secondly, the animal must be adapted to competition

and other interactions with other species in the community (predation, etc.) This is the niche.

Ecosystem Diversity: The diversity of biological communities and their

physical environment. The species composition, physical structure and processes within an ecosystem determine the level of biodiversity.

Biodiversity: The variation in life on Earth reflected at all levels, from

various ecosystems and species, to the genetic variation within a species.

Conservation Biology: A field of science that deals with threats to

biodiversity. The goals of conservation biology are to investigate human impacts of biodiversity and to develop approaches to prevent extinction

through stewardship of entire biological communities.

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Amazon Ecosystem

AquaFacts: The Amazon

The Amazon River and its tributaries in northern South America, cover an area of over 6,000,000 square km. The Amazon ecosystem comprises about

40 percent of Brazil‘s total area, and is bounded by the Guiana Highlands to the north, the Andes Mountain Ranges to the west, the Brazilian central

plateau to the south, and the Atlantic Ocean to the east.

This tropical rainforest is perpetually hot and humid, green and flowering, wet and waterlogged, and is fed and drained by the largest river system in

the world.

The Amazon rainforest in South America can be divided into five layers:

Emergence (50 metres): Scattered trees tower above the forest top reaching for light and

rain. Butterflies, birds of prey and some other animals live at this level.

Canopy: The crowns of many tall trees reach

up to 30 metres forming a canopy teeming with life. Climbing bush ropes called lianas hang in

loops between the trees. Epiphytes are plants that grow attached to other plants. The animals

that live at this level are mainly fruit and leaf eaters such as parrots and toucans, gibbons,

flying squirrels, tree boas, lemurs and howler monkeys. Specially adapted to their treetop world, the species of this level have evolved features such as

prehensile tails and sharp claws for climbing, or flaps of skin for gliding through the air without wings.

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Understory/Middle Layer (12 metres): Formed by smaller trees

interwoven with vines and branches, the dense middle layer has open areas where tree crowns do not meet. This allows some light to penetrate and

enables the birds and mammals to fly or glide. Many animals move easily through the trees of the middle level; monkeys, civets (related to

mongooses) and ocelots (spotted cat) to name a few. Flying insects are prey for birds and oversized bats. Snails and crabs inhabit tree trunks, sharing

the jungle with frogs and climbing snakes.

Shrub Layer: Shrubs, dwarf trees and plants dominate the shrub layer, which grows to about 3 metres in relative darkness. The animals of this layer

are mainly nocturnal creatures and include tapirs, anteaters, owls and kinkajous (related to raccoons). Many species pass through this area as they

travel from ground level up pathways to the treetops.

Herb Layer/Forest Floor: Ferns, ginger and other small plants form the

sparse herb layer. Many types of animals inhabit the floor. Tapirs, jaguarondi, brocket deer and flightless birds are among the creatures of the

jungle floor where life is quiet by day and busy by night. Plants in this layer do not receive much sunlight. Only two percent of the sun‘s energy

penetrates down here so plants must be extremely good at capturing what light does get through.

In the Graham Amazon Gallery at the Vancouver Aquarium our rainforest is

divided into four layers – the Canopy, Understory, Shrub Layer and Forest Floor.

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Arctic Ecosystem

AquaFacts: The Arctic

What is the Arctic like? Many people

imagine a cold, snowy land, but surprisingly, not much snow falls at all!

On October 9, 2009, the Vancouver

Aquarium opened its latest exhibit: Canada‘s Arctic. This link has extensive information about the Arctic, our new gallery and more…

Given the intense climatic conditions in the Arctic, all life within this area

must be able to adapt and live in extreme cold. This is perhaps not as difficult an adaptation as being able to adjust to wide fluctuations in

temperature.

Keeping Warm

Warm-blooded animals minimize heat loss by:

reducing the size of appendages that are not covered with a thick layer of insulating blubber (beluga flippers and flukes are quite small and

the dorsal fin is replaced by a dorsal ridge) controlling blood supply to areas (i.e., extremities) where warm blood

may be cooled quickly (if too warm, blood is shunted to extremities to cool off)

thick layers of fat or blubber insulates, streamlines and provides a rich

store of energy. Thirty-three percent of a beluga‘s weight is blubber. Polar bears have blubber, and black skin.

Fish and Invertebrates minimize heat loss by:

Fresh water freezes at 0O C, but salt water can drop to -3 O C before

freezing. Most fish freeze at -0.6 O C to -0.8 O C. Somehow in Arctic fishes, the fluids inside their bodies adjust to the temperature of salt

water, but they must stay deep to avoid ice crystals. If they touch a single one, the fish will freeze solid. Arctic cod have an antifreeze (a

glycoprotein) in the blood so they can enter the icy surface waters and avoid freezing.

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Ice

Ice, the dominant feature in Arctic marine ecosystems, continuously sculpts

the coastal landscape and acts as a major limiting factor to all biological activity.

Sound

With up to 24 hours of darkness each day during the Arctic winter, animals

must rely on sound rather than light to detect their surroundings. Whales

use echolocation - a series of clicking sounds are emitted which bounce off the whale‘s surroundings and return providing a 3D image. Sound is picked

up by a whale‘s oil-filled lower jawbone or in the case of belugas by their oil filled melon. Check out the Beluga Underwater Viewing Area. Look for the

tiny vestigial outer ears on the belugas, just behind their eyes. Many marine mammals use sound to communicate, navigate, hunt or find openings in the

ice.

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North Pacific Ecosystem

Including islands, our Pacific coastline stretches

29,489 km – 11% of Canada‘s ocean shoreline! It overlaps four distinct continental plates with several

related fault zones, making it the most earthquake prone area in Canada.

Tides are moderate ranging from 2.5 m to 4.0 m with

strong tidal currents in numerous narrows. Water temperatures are fairly constant throughout the year, ranging from 6° to 14° C overall and reaching

18° to 20° C in sheltered areas during the warmest months.

Marine invertebrate diversity is the richest in Canada with over 3,800 species. This represents three times the number of invertebrate species on

the Atlantic coast and 3.5% of the world‘s marine invertebrates.

Over 400 species of fish can be found off our coast, including rockfish,

lingcod, greenlings, kelp fish and five species of Pacific salmon. Follow this link for details on Research being conducted by the Vancouver Aquarium on

some of these species.

These elements work together to produce one of the most productive marine ecosystems on the planet.

The Continental Shelf

This is the part of the submerged coast that gradually slopes seaward, with

depths to 200 m. Large portions of the shelf have been influenced by glaciations during the last ice age, leaving behind shallow banks, deep

basins and troughs. Currents create upwelling as they encounter these features, while prevailing winds generate upwelling along the coast in spring

and summer. This upwelling brings nutrient-rich waters to the surface creating an ideal environment for plankton growth, which in turn supports

dense concentrations of fish, as well as marine birds and mammals.

Follow this link for information on the Pacific Ocean Shelf Tracking Project (POST).

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The Outer Coast

A combination of uplift and erosion has created a complex and rugged coast. Inlets, headlands, numerous islands, reefs, sea caves, vertical sea cliffs

bordered by flat sandstone benches, shallow bays, rocky intertidal zones, small deltas, and extensive sand and gravel beaches are all part of this

wave-battered coast.

A variety of intertidal and sub-tidal habitats are home to numerous marine invertebrates, fish and abundant algae. Important Pacific salmon and

steelhead trout rivers exist throughout the region. Each fall adults can be

found making the difficult journey upstream back to their spawning grounds. Elusive six-gill sharks, normally found living at depths of over 1,200m, come

into the shallow waters of Barkley Sound and Hornby Island each year. The largest groupings of breeding seabirds in British Columbia are found in this

region, mainly on Triangle and Sartine Islands. Over 900,000 pairs breed in this region!

In the spring, more than 21,000 grey whales migrate

along the West Coast to summer feeding grounds in Alaska, though a couple hundred individuals spend the

summer in BC waters. Killer whales, harbour porpoises, Dall‘s porpoises, Pacific white-sided dolphins, humpback

whales and fin whales can also be spotted along the coast. California sea lions and harbour seals are both

common in this region. Sea otters, which vanished from

Canadian waters in 1929, were successfully re-introduced in this region and the resulting colonies are

flourishing.

Follow this link for information on Cetacean Research and Marine Mammal Rescue in BC.

Strait of Georgia

Located between Vancouver Island and the Lower Mainland, the Strait of

Georgia is a relatively deep basin with an average depth of 155m. An indented coastline of long, steep-sided fjords, inlets, islands, passages and

steep channels characterizes the mainland. In contrast, eastern Vancouver Island is marked by a regular undulating coastline with extensive coastal

bluffs, deeply cut river valleys and few inlets. Check out the exhibits in the Treasures of BC Coast Gallery to get a sense of the diversity in our waters.

Also, there are photomurals online: Unmasking BC‘s Waters.

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The sub-tidal communities are particularly diverse in this region and vary greatly with temperature and currents. The Fraser River, which drains about

one quarter of British Columbia, is the most important salmon-producing river in North America. Salmon pass through Georgia Strait as they return

to spawn in their native stream. Juvenile salmon call the estuary (the mouth of a river where tidal effects are evident and where fresh and salt water mix)

home as they adjust for their life in the open ocean. In addition, the Strait of Georgia has important Pacific herring spawning grounds and is home to a

small number of breeding seabirds. The region is extremely important to the two million shorebirds, grebes, loons, ducks and geese which use these

estuaries, tidal flats and coastal waters as summering, staging and wintering grounds.

A group of some 90 resident killer whales in three pods spend much of the

year in the southern Gulf Islands and San Juan Islands. Harbour seals are

year-round residents with numerous haul-outs throughout the region. Follow this link for information on how many Harbour seals are currently patients at

our Marine Mammal Rescue Centre.

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Tropical Reef Ecosystem

Coral reefs are among the most ancient of ecosystem types, dating back to the

Mesozoic era some 225 million years ago. Modern reefs can be as much as 2.5 million

years old.

Although they cover only a tiny fraction (less than 0.2%) of the ocean‘s bottom, coral reefs capture about half of all the calcium flowing into

the ocean every year, fixing it into calcium carbonate rock at very high rates. Coral reefs release carbon dioxide to the atmosphere due to the

chemistry of calcium carbonate precipitation. The release of carbon dioxide from coral reefs is very small (probably less than 100 million tons of carbon

per year) relative to emissions due to fossil fuel combustion (about 5.7 billion tons of carbon per year).

Coral reefs are massive limestone structures that provide shelter for nearly 25% of all marine life! A good way to imagine a coral reef is to think of it as

a bustling city or community with the buildings made of coral, and thousands of inhabitants carrying out their business. In this sense, a coral reef is like a

metropolis of the sea. Although coral is often mistaken for rock or plant, it is composed of tiny, fragile animals called coral polyps.

Coral polyps are related to sea anemones and jellyfish and are classified as

cnidarians, animals that possess stinging cells in their tentacles for defense and catching prey.

There are hard corals and soft corals. Hard corals are the architects of the

reef and their skeletons are made out of limestone which is as hard as rock. The coral habitat is different from most habitats because coral is a living

organism. Therefore the presence of the reef depends on whether or not the coral polyps can survive and grow. Coral reefs grow in relatively warm, clear

and shallow water and to help them grow their tissues contain tiny algae

known as zooxanthellae which provide nutrients such as oxygen and carbohydrates to the coral.

Coral reefs are very delicate, fragile habitats and can easily be destroyed or

suffer damage if the ideal conditions for coral to grow change in any way. So it is very important to protect and manage coral reef areas so that they

remain healthy, continue to support the huge variety of animal and plant life that inhabit them, and provide enjoyment for future generations.

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The Intertidal Zone

Only hardy plants and animals can live in the harsh

habitats between the high and low tides of the sea, called the intertidal zone. Rapid changes in exposure,

from air to water, make the intertidal zone an extremely challenging environment for animals to survive in.

Changing tidal levels create distinct zones of life, often resulting in horizontal bands along many seashores. The

animals and plants living in these intertidal habitats settle themselves in specific layers along the shore

depending on their tolerance to the sun, air and water.

Despite the challenges of the intertidal zone, a riotous profusion of life thrives and fills the many niches created by the widely varying conditions.

The physical rigors of the intertidal region combined with abundant and varied forms of life, result in intense and dynamic competition for resources

and space.

Shoreline space is at a premium and competition for it is intense. All shores

are extremely rich habitats with every square centimetre of rock, sand and crevice occupied by some form of life. Plants and animals frequently grow on

top of each other, sometimes several layers deep, when it is impossible to spread out horizontally.

The behaviours, diets, and deaths of seashore animals are closely

interconnected. Algae capture light from the sun and nutrients from the salt water, providing food for snails, sea urchins, and other plant eaters.

Sea stars, sea anemones, small fishes and other predators eat these plant

eaters. Scavengers, such as shrimps and crabs, eat live and dead plant and animal matter. Barnacles, mussels and other filter feeders sift tiny animals

and plants, called plankton, out of the water for their dinners. Algae recolonize areas where plant eaters have bared surfaces, and the intricate

cycle of growing, grazing, and predating continues.

The tides that cause these zones generally rise and fall twice each day and

follow the lunar cycle. Tidal movements are caused by the gravitational pull of the moon and to a lesser extent, the sun. These two interplanetary bodies

pull our planet‘s water toward them, creating oceanic bulges on the Earth‘s surface. When the sun and moon are pulling in the same direction, the sun

behind the moon, their pull is the greatest, and the tidal fluctuations most extreme.

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Rocky Shores

Dense forests, damp fogs and waves foaming on jagged

rocks form a scene characteristic of our B.C. coast. It is on these wave-beaten

rocky shores that the greatest abundance and largest variety of seashore

creatures live. A rocky shore is crowded with plants and animals competing for food, light,

shelter and the little space available. Occupying every nook and cranny,

organisms can be found inhabiting many different ―homes.‖ They live on or under rocks, in crevices, in tidepools, under protective curtains of seaweeds,

in the anchors of algae or even apartment-style, on top of one another! To survive the rigors of a seashore existence, rocky shore creatures show some

complex and fascinating adaptations.

Within the intertidal zone, more than seven sub-zones may exist. Each sub-zone is comprised of a different community of plants and animals. The

physical location of each of these subzones is determined by a fascinating interplay of biological interactions and physiological tolerances.

The uppermost zone of the seashore is the spray zone, also called the

supralittoral zone. This transition area between the influence of land and sea is exposed to air, but regularly receives the ocean‘s spray. This zone appears

almost barren when compared to the profusion of life that thrives in the

lower zones of the seashore. The animals and plants of the spray zone are almost terrestrial and some cannot survive extended submersion in

seawater.

Within the intertidal zone at low tide, light and temperature levels may exceed or fall below those of the sea. A heavy rainfall can lower the salinity

of any nearby saltwater pools forcing animals living there to adjust their body chemistries. Herons, gulls, and other air-based and land predators can

access exposed seashore inhabitants. Particular tidal sequences may result in levels low enough to separate organisms from the sea for many days

leaving ―water-breathing‖ animals high and dry.

Waves generated by violent storms can carry pebbles, rocks and other missiles as the tides rise and fall. Seaweeds and creatures must be very

tough to survive the constant changes in their habitats. At high tide, the

opposite occurs—the amount of light decreases and predators are now primarily marine.

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The lowest zone, the subtidal zone, is located below the low-tide line. It is

a more stable zone where conditions change little on a daily basis. Wave-action effects are minimal, temperatures change only seasonally, and

associations and interactions among animals are more permanently established. The animals and plants that live here do not need to invest as

much energy into surviving physical stresses. Instead biological competition and predation are the main difficulties to be overcome by subtidal creatures.

In general, the upper limits of the plants and animals of each sub-zone are

determined by physical factors while the lower limits are set by biological factors such as competition and predation.

Sandy Shores

Sandy shores are unstable, in continual motion and reshaped by every wave.

The ever-shifting substrate and harsh conditions of the outer coast make survival impossible for all but a few hardy animals—the flora and fauna of

unprotected sandy shores appear extremely sparse when compared to the richness of the rocky shores.

Conversely, in the quiet, sheltered waters of sand and mud flats, a utopia

exists for many organisms. The sand-mud mixture is rich in food, wave action is minimal and the substrate is usually still. At first glance these

shores may appear empty of life, but just below their bare surfaces many well-adapted creatures thrive.

The zonation typical of rocky shores does not exist as clearly on sandy areas. Generally, however, the upper

reaches of sandy shores are poorly inhabited as the dry, loose, continually shifting sand is not well

tolerated by plants and animals. The damp lower regions support more bountiful arrays of life.

Shoreline Litter

To learn about the impacts that Litter can have on the

Intertidal ecosystem and animals follow this link: Shoreline Litter Impacts.

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Classification A Swedish scientist named Carolus Linnaeus created a scientific system for

naming living organisms in the 1700‘s. Linnaeus named plants and animals in a way which made it possible to identify each species and to document

their relationships to each other.

Each organism has only one scientific name, although it may have many common names. Scientific names are usually formed through a combination

of Greek or Latin root words. These names frequently refer to the organism‘s

most obvious characteristics, the geographic area where it naturally lives, or the scientist who first described or discovered it. The scientific names of

organisms often reveal them.

In a similar way to how surnames describe the family relationships of people, the kingdom, phylum, class, order, family and genus divisions tell us

even more about the relationships among the innumerable forms of life. These inter-relationships are measured in terms of the structure and

function of the anatomy of the organisms.

Kingdoms are the most general divisions and separate life into five basic groups: bacteria, protista, plants, fungi and animals. Kingdoms are broken

into phyla. Animals within each phylum can be very different in size, appearance and habitat, but all share some common features.

Each phylum, in turn, is divided into one or more classes, the classes into orders, orders into families, families into genera, and the genera into

species. Each division describes the increasing number of characteristics that the organisms within them share.

The order of these groupings can be remembered with the simple

mnemonic: King Philip Came Over For Ginger Snaps

An example of how this classification works is given for the purple shore

crab: Kingdom Animalia

Phylum Arthropoda Class Malacostraca

Order Decapoda

Family Grapsidae Genus Hemigrapsus

Species nudus

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A very closely related species, the green shore crab, Hemigrapsus oregonensis, shares the same Kingdom, Phylum, Class, Order, Family and

Genus with the purple shore crab, Hemigrapsus nudus. Only the species name, oregonensis, is different. These two species are very similar with the

exception of colour, the presence of a few ―hairs‖ on the legs of one species and their habitats. Their scientific names reflect their similarities and

differences.

A flatworm, with its completely different body structure, belongs to a different phylum, the Platyhelminthes. A cedar tree, a plant that generates

its energy from light, oxygen and water, and has a basic cellular structure which differs from animals, belongs in an entirely different kingdom, the

Plantae.

What Makes a…:

Mammal a Mammal

Warm blooded

Fur or hair

Four chambered heart Live birth

Feed babies milk

Bird a Bird

Lays eggs Has hollow bones

Has feathers Endothermic

(self regulated body heat)

Insect an Insect

Exoskeleton

3 distinct body segments (head, thorax, abdomen)

6 legs

Arachnid an Arachnid

Exoskeleton 2 body segments

(cephalothorax, abdomen) 8 legs

Fish a Fish

Scales Breathes with gills

Lays eggs or live birth depending on species

Lives in water always

Reptile a Reptile

Cold blooded Lay hard or leathery eggs in sand

or dirt Dry scaly skin

Ectothermic (gets body heat from environment)

Amphibian an Amphibian

Lays soft eggs in water Breathes through skin

Cold blooded Thin scaleless skin

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Marine Invertebrates

AquaFacts: Marine Invertebrates

What is an Invertebrate?

Simply stated, an invertebrate is an animal with no backbone (in-VUR-teh-brayte). There are many more types of animals without backbones than

there are animals with them (vertebrates: VUR-the-braytes). In fact, 97% of all animals on earth are invertebrates!

Invertebrates are found in a huge range of habitats worldwide from glaciers

to deep-sea thermal vents, and their range of body types is amazing.

The animals in this section are organized by phylum (FYE-lum), the same way scientists usually order them. A phylum is a broad designation that

groups animals that are presumably descended from a common ancestor and share a common characteristic.

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Phylum Porifera (POUR-if-er-ah); ―por‖ = pore; ―fer‖ = bearing

Sponges

More than 5,000 species of these simple, colonial animals exist worldwide.

They range in shape from small nodules to lumpy carpetlike forms and massive, vaselike structures. Despite a wide variety of appearances, all

sponges are based on essentially the same basic body plan—a vaselike structure that is attached at the bottom to rocks, shells or the sea bottom.

Sponges are composed of several kinds of cells, but do not have true

tissues.

These animals lack muscles, nerves, sensory cells, and even a mouth. They do have specialized cells, including collar cells, that beat their whiplike tails

to create a current which draws water into the many small pores that puncture their body walls. The water entry points are called ostia (aw-

STEEah, plural; ostium: aw-STEE-um, singular). Sponges filter the newly entered sea water to remove oxygen and microscopic organisms, called

plankton. The water then flows out of the animals through a large craterlike hole, or series of holes, called the oscula (aus-KEW-lah, plural; osculum:

aus-KEW-lum, singular).

Some sponges use spicules, small skeletal elements imbedded in their body walls, to make their bodies spiny and hard. These elements are made of

protein, calcium carbonate or silica. Spicules make sponges less inviting to

most predators, but some sea slugs and sea snails persevere and eat them anyway.

The species of sponges we use in bathtubs do not grow in the coastal waters

off B.C.—and, of course, neon-coloured plastic sponges are mimics of the real ones!

In the Northeast Pacific seas, sponges are often brightly coloured mats of

greens, purples, golds, reds and grays. These irregularly shaped animals grow on hard surfaces and feel like velvet or rubber to the gentle touch.

They can reach thicknesses of two centimetres. Other sponges, called boring sponges, grow on the shells of many molluscs. They use chemicals to

dissolve the shell and cause it to disintegrate.

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Phylum Cnidaria (NYE-dar-ee-ah); ―cnid‖ = nettle; ―aria‖

Cnidaria

Beachwalkers encountering cnidarians (NYE-dar-ee-anz) often confuse them with plants. Sticky sea anemones (ah-NEM-aw-nees) and their soft sea pen

and jellyfish relatives resemble flowers, feathery quill pens and flying saucers more than they do other animals.

Cnidarians have two basic body types: a free-swimming medusa, well known as the jellyfish, and a stationary polyp (PAUL-up) of which sea anemones are

large examples. Some species have both medusa and polyp forms as part of their life cycles. Many others are either polypoid or medusoid.

Cnidarians are essentially hollow bags with a central mouth. Both medusa

and polyps have radially symmetrical bodies—that is, their bodies are formed in a circle around a central point. The central cavity acts as both

mouth and anus. A fringe of tentacles laced with sticky, stinging cells, called cnidocytes (nye-DOH-sites), surrounds this opening.

The stinging cells shoot minute harpoonlike devices at whatever touches the animal—even your finger. In virtually all local species, potential prey or

predators can be immobilized as these tiny stinging harpoon mechanisms can wrap themselves around small organisms, penetrate thin coverings (not

your skin), inject venoms, or perform combinations of all three of these

feats. The tentacles may then manoeuvre appropriately-sized prey into the mouth. Waste material is ―spat‖ out through the mouth/anus.

Class Hydrozoa

Hydroids Most types of fernlike hydroids attach themselves to

rocks, kelps, wharf pilings, shells, or virtually any hard object. The stalks of colonial species can grow to 15-

centimetres tall, but many are smaller. These primitive animals are capped with bell-shaped polyps. Each

individual animal is joined to the rest of the colony and shares a common digestive system.

Individual members of the hydroid colony, called polyps, are usually

specialized for different functions. Feeding polyps gather food and defensive

polyps sting. Like all their cnidarian relatives, hydroids have stinging cells that they launch at predators to defend themselves or to immobilize their

prey. The miniature harpoonlike stinging cells explode upon contact with tiny organisms floating in the water, called plankton. The hydroids‘ tiny tentacles

then guide the paralyzed prey into their mouths.

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Another specialized type of polyp is responsible for reproduction. These polyps break off to produce free-swimming medusas which resemble tiny

jellyfishes, although not all hydroid species have a medusoid stage. These medusas reproduce sexually, shedding eggs or sperm into the water.

Fertilized eggs develop into mobile larvae which later settle on solid ground and grow into a new sessile generation of hydroids. This process is known as

alternation of generations or metagenesis.

Class Scyphozoa True Jellyfish

AquaFacts: Jellyfish Jellyfishes are composed largely of a gelatinous

substance, called the mesoglea, or more commonly ―jelly‖—hence the name ―jellyfish‖.

Jellyfishes often resemble upside-down,

transparent bowls with tentacles extending from their rims. Their many tentacles host stinging

cells that are used to capture planktonic prey, small crustaceans and fishes, and as a defense

against predators. In B.C., the giant red jellyfish can give you a severe and nasty rash, so it is best to leave them alone when you are swimming or see

them washed up on the beach.

Jellyfishes swim by contracting their bells in mesmerizing, pulsating movements. They are not strong swimmers and drift horizontally with waves

and currents, sometimes accumulating in immense numbers in quiet bays and estuaries. Many jellyfishes can propel themselves vertically to the

surface during cloudy weather or at dusk.

The sex organs, or gonads, are often horseshoe-shaped and visible through

the clear bells, or mesogleas, of many jellyfishes.Most species of jellyfishes are dioecious—that is, sexes are separate and individual medusas are either

male or female. Eggs and sperm are released by females and males respectively into the open ocean. Fertilized eggs settle and develop into tiny

polyps that resemble hydroids. Eventually many young medusas budd off and grow into mature jellyfishes, and the cycle continues.

Class Anthozoa

Sea Anemones Sea anemones are simple, well-armed animals. Their

many, petal-like tentacles are laced with stinging cells that immobilize prey, such as small shrimps and crabs.

Once anemones have successfully captured their dinner,

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they use their tentacles to manoeuvre it into their centrally located mouths.

Anemones spit out the indigestible parts of their meals, including pieces of shell.

At low tide, sea anemones that are attached to rocks or burrowed into sandy

beaches prevent themselves from drying out by tucking their tentacles into the middle of their cylindrical bases. This action traps water inside their

central cavities. Sea anemones often stick pieces of shells or tiny rocks to their columns to camouflage themselves. Many exposed anemones look

more like drab stewed tomatoes with beach flotsam decorations than the exquisite aquatic flowers they resemble when seen ―open‖ underwater.

Even when their tentacles are ―out‖ in tidepools, or underwater, the stinging

cells of sea anemones are harmless to most humans. Take care to gently use your pinky finger if you wish to touch one of these soft creatures.

Corals Coral polyps resemble miniature sea anemones, complete with stinging cells.

Unlike sea anemones, corals secrete skeletons and are frequently colonial. Solitary coral species also exist, such as the one-centimetre-tall orange cup

coral found in B.C.‘s waters. This lilliputan coral feeds on the tiny plankton that it traps in its clear tentacles. When orange cup corals die they leave

bony, white, calcium carbonate skeletons on the rocks where they had lived. Other corals produce skeletons made of a soft protein called gorgonin (gore-

GOHnihn). Unlike many tropical species, the corals that live in our temperate seas do not build reefs.

Sea Pens

Sea pens are colonial animals that inhabit sandy and muddy areas. Sea pen colony members include many small polyps that

form the ―feather‖ on top, and one elongate, cylindrical polyp

with a stemlike anchor. The masses of tiny feeding polyps lining the branches at the top of the colony‘s stalk are armed with

stinging cells. If disturbed by a predator, sea pens can glow a brilliant green and contract their column muscles to withdraw

themselves into the sand.

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Phylum Mollusca (MOLL-us-ka); ―moll‖=soft

Molluscs

The molluscs are a diverse group of more than 100,000 species of living animals including clams, snails, limpets, sea slugs, octopuses, squids and

abalones. Most molluscs can be identified by three features: a large muscular foot, hard shells they create to cover their soft bodies, and a

toothed, rasping tongue, called a radula (rad-YOU-lah). Octopuses and squids have deviated from the general mollusc body plan. In both of these

types of animals, the foot has evolved into a number of many-suckered arms. Neither has a shell, but squids have a stiff internal rod, called a pen.

Both octopuses and squids have a hard, bird-like beak which they use to bite prey.

Class Gastrapoda

Sea Snails Sea snails make the shells that they carry on their backs and

use them as mobile homes. They use their single, large foot

to move slowly and for holding onto the ocean bottom. Most snails can pull their foot into their shells and firmly seal the

―door‖ shut with the operculum (oh-PER-kew-lum), a tough, oval-shaped piece of material. Many snails scrape and eat algae from rocks

with their sandpaper-like tongues, often leaving a maze of clear snailtrails behind them. Some sea snails use their rasping radulas to bore holes in

other creatures‘ shells to feast on the animals inside.

Nudibranchs Nudibranchs are snails that have lost their shells. These marine

slugs have a pair of sensory tentacles, called rhinopores, in the head region. Some species are very well camouflaged and blend

with the browns, blacks and greens of their habitats. Other nudibranchs are bright, flamboyant and frilly and employ their loud

colours to warn potential predators to stay away. Many species

contain body toxins or carry an arsenal of undischarged stinging cells that are stored in projections, called ceratae, along their

backs. These stinging cells are acquired when eating cnidarians. Few animals eat adult nudibranchs. The diet of nudibranchs, however, includes sponges

and various cnidarians.

Mussels Mussels use their muscles to tightly close their two bluish-brown

shells to protect their soft, moist insides from both predators and the drying effect of low tides. They attach themselves in large

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clumps to rocks and pilings with tough, byssal (BYE-sahl) threads and eat

the miniscule plants and animals that they filter from the water.

Clams Clams have two shells which they shut together tightly to

protect their soft insides. They live in the sandy or muddy bottoms of beaches or the sea. To eat, they extend long

tubes, called siphons, to the surface of the sea floor and filter small plants and animals, called plankton, out of the water. When

disturbed, these animals withdraw their siphons, pulling them down toward their shelled bodies. This gives clam diggers the false idea that all clams dig

deeper into the sand to escape predators. Clams are a favourite food of some sea stars.

Chitons

The flattened bodies of chitons (KYE-tons) are covered by eight partially

overlapping shell plates. Chitons‘ strong feet and low profiles allow them to cling to rocks in turbulent surf and strong currents. Some chitons have

eyespots that sense light. Many chitons feed at night, using their toothed tongues to scrape algae off rocks.

Class Cephalapoda

AquaFacts: Octopus and Squid

Octopus All octopuses use their well-developed eyes to scan for prey and predators.

They use their eight sucker-lined arms to grasp potential dinner items, such

as crabs, snails, oysters, abalone, clams, mussels and small fishes. They transfer their prey to their mouth, located on their undersides, in the middle

of their many arms.

When octopuses see predators, they flee as quickly as possible, often hidden by murky clouds of ink that they

squirt behind them into the water to onfuse any pursuers.

Octopuses use other talents to avoid predators and hunt prey—they shape-

shift and colour-change. They can squeeze their soft bodies through very, very small openings under rocks and at the entrances of caves, where they

often live. Octopuses are also masters of skin-colour changes, either

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blending with their surroundings or pulsating red when alarmed. These

disguise artists can even alter the texture of their skin to match their backgrounds.

Squids

Squids possess the ability to change their colour and instantaneously create intricate, fluctuating patterns on their bodies. They use this talent to blend

with their environments and hide from predators. They can also produce light, called bioluminescence (bye-oh-LOOM-in-ess-ense). Such abilities help

to disguise the shape of their bodies or even startle predators, including fishes and a variety of marine mammals.

Squids, like octopuses, have a sac from which they shoot jets of ink. These

smoke screens provide cover and confuse predators while allowing the squids to escape. The ink clouds resemble the size and shape of their bodies

so a predator with poor eyesight may attack the ink cloud instead of the

fleeing squid. Some inks also act as eye irritants.

Like octopuses, squids no longer have external shells, but they do have some hard parts. Squids have an internal stiffening rod, called a pen.

They also have a parrotlike beak in their mouths that they use to bite the fishes and shrimps on which they feed.

Some squids form large schools, which may confuse potential predators.

These schools often rapidly change their direction to escape predators. Some species of squid travel at high speeds and leap out of the water to

―fly‖ away from their predators. These species have been observed to fly at speeds of 26 kilometres per hour and leap a distance of 20 metres.

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Phylum Arthropoda (arth-ROE-poe-dah);―arthro‖=jointed;

―poda‖=foot Arthropods

Jointed legs define the arthropods, and the phylum derives its name from

this feature (arthro=joint and pod=leg). These appendages have been adapted to a myriad of functions including moving, sensing, feeding, defense

and offense.

Each segment of the bodies of primitive arthropods bears a pair of appendages, indicating a probable relationship to the annelids. The number

of segments and, consequently, the number of appendages, have tended to decrease in more complex arthropods, such as crabs and shrimps.

Arthropods also possess an external skeleton made of chitin (KYE-tin). In

many marine arthropods, this chitinous exoskeleton is reinforced with calcium carbonate. These animals must moult their exoskeletons and

develop larger ones as they grow.

In most species moulting continues throughout the life of the individual at

varying intervals depending on the age of the animal and the availability of food. In some cases moulting may occur seasonally. Prior to the shedding of

the old exoskeleton there is an increase in food storage and blood calcium. A new, soft skeleton is created underneath the old one, and the body tissues

swell with water. The old exoskeleton eventually splits and the vulnerable creatures struggle free. The newly formed, soft skeleton offers little

protection. The animal continues to swell with water, stretching the new covering before it hardens. Once the shell hardens, the creature ―grows‖ into

its new shell by adding tissue. In times of famine, many arthropods can actually shrink during a moult.

Class Crustacae

The major marine component of the Arthropoda is the class Crustacea.

Crustaceans are distinguished from insects by the presence of two pairs of antennae as compared to the insects‘ single pair. The crustacean body is

divided into a head, thorax and abdomen. The head bears the antennae, antennules, mouth parts, (mandibles, maxillae, maxillipeds) and the eyes.

The thorax, like the head, is also covered by a hard carapace. Often the head and thorax are fused into a single unit—the cephalothorax as in the

shrimps and crabs.

There are over 32,000 known crustacean species which occupy most marine habitats, much as the insects do on land. And, much like insects, they are

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extremely important to the ecosystems they inhabit. The developing larvae

of the bottom-dwelling forms and many adult species of crustaceans are very small and are a major component of the zooplankton. These tiny

animals form a vital base for the entire marine food web.

Crabs Most crabs have hard shells that cover their bodies,

antennae, powerful claws, and two to four pairs of walking legs. Crabs use their specialized pincers and appendages as

knives, forks and spoons to eat everything from marine worms to seaweeds. Most crabs use eight legs to move quickly—sideways.

Hermit Crabs

Hermit crabs differ from other types of crabs as they have soft abdomens that make them vulnerable to predators and they

use only two pairs of legs for walking. Their remaining

specialized two pairs of legs are used to hold their bodies inside the shells, tube worms and sponges that they use to keep their

soft bellies from harm. Many hermit crabs will engage in combat with each other for larger shells, but usually do not fight with the

original owners for possession of the shells. Their claws can be used as a door to seal out predators.

Barnacles

Barnacles resemble miniature, grey volcanoes cemented to rocks. To feed, they open the tiny, movable, trapdoor plates at

the ―summit‖ of their shells, and use six pairs of feathery, jointed legs to sift through the water for the tiny animals and

plants that they eat. When the barnacles have finished feeding, they close these plates, sealing themselves inside for protection. They also close them

to retain moisture inside their shells during low tide. Try not to step on these

tiny animals when you are exploring the seashore.

Shrimps There are over 80 species of shrimps along the West

Coast. Their prey includes small invertebrates and worms. They avoid their predators by camouflage and

by ―flipping‖ away. To make an escape, shrimps spread the ends of their tails as wide as they can and then pull

them forward using the large muscles in their abdomen. This propels the shrimps backwards quickly. To go forward, shrimps can

walk, jump or, less frequently, swim. Shrimps are fastidious animals, scrubbing themselves with tiny grooming brushes.

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Phylum Enchinodermata (ee-KYE-noh-der-mah-tah);

―echino‖= spiny; ―dermata‖= skin Echinoderms

Echinoderms are exclusively marine and adapted to a bottom dwelling

existence. The phylum name Echinodermata means ―spiny skinned‖ and is derived from their characteristic spines, called ossicles. Ossicles are made up

of hard calcareous bits embedded in their skins. Like us, echinoderms

possess an internal skeleton. Their skeleton, however, is composed of interlocking calcite plates. Although many living echinoderms feel shell-like,

the outside layer consists of delicate skin, muscles and various other organs.

The typical adult echinoderm body consists of five similar sections repeating around a central point. This is called pentaradial symmetry. This five-rayed

symmetry, most readily seen in sea stars, is a secondary development. Their early bilaterally symmetric larval development before metamorphosis is very

similar to that of the chordates.

Most echinoderms move by using their tube feet which are long flexible appendages usually tipped with a suction cup. These are part of a water

vascular system, consisting of interconnecting fluid-filled hydraulic canals. Tube feet also function in respiration, sensing and food gathering.

Many echinoderms also have pedicellaria (pincers). Depending on the species, these tiny two to five fingered grasping appendages can function in

food gathering, cleaning and defense against parasites, large predators or the settling planktonic larvae of barnacles and others.

Echinoderm sexes are generally separate. The fertilization and development

of their young are usually external.

Class Asteroidea Sea Stars

Most sea stars have five arms, but some species, such as the sunflower star, can have up to 26! If sea stars

lose any of their arms, they can usually grow a new one. These animals use hundreds of suction-tipped

tube feet located on the undersides of each arm to

move slowly along the bottom of the ocean.

Most sea stars eat by using their tube feet to pry apart the shells of their mussel, clam or snail dinners. Once they have ―opened‖ their prey, they

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push their stomachs out of their bodies through their mouths. Sea stars

digest the soft meat of their prey outside their bodies. They use eyespots located at the tip of each arm to detect how light or dark

their surroundings are.

Class Echinoidea Sea Urchins

Sea urchins are bristling balls of spines. Like porcupines, sea urchins use spines as protection. They use five double rows of

tube feet to anchor themselves to the sea bottom, to move slowly, to seize bits of food, and to keep their spines free of

debris. They also use five interconnecting teeth on their undersides to graze kelp and other seaweeds. This feeding

apparatus is called Aristotle‘s lantern.

Sand Dollars

Sand dollars are essentially flattened sea urchins. Living sand dollars have a velvety, dark purple or black coat of short spines—the white sand dollars

that you see on the beach are the skeletons of once living animals. Sand dollars use their spines to move and to burrow in sand.

The top surfaces of sand dollars are decorated with a five-petal flower

design. The petals of this flower are called petaloids and host modified tube feet that act primarily as respiratory organs.

Dense clusters of up to 1,000 sand dollars per square metre dig themselves

out from under the sand as the tide rolls in, allowing the sea to wash over them. They capture debris and food with their tube feet and pass it into their

mouths which contain modified Aristotle‘s lanterns, similar to the five-tooth rings found in the mouths of sea urchins. Sand dollars rebury themselves as

the tide rollsout. Young sand dollars ingest extra-heavy bits of sand for

ballast, like divers‘ weight belts, to help prevent themselves from being swept away by waves.

To reproduce, many female and male sand dollars simultaneously release

eggs and sperm into the water— this is called broadcast fertilization.

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Class Holothuroidea

Sea Cucumbers Most sea cucumbers are the shape of—yes cucumbers—and some are the

consistency of jello. Although some sea cucumbers do have soft spines and hundreds of tube feet, sea cucumbers do not outwardly resemble their close

relatives, the sea stars and the sand dollars. The internal organs of sea cucumbers are arranged into five equal parts, in a similar fashion to their

relatives. Some sea cucumbers mop up food from the water or the ocean bottom using the sticky feeding trees, or tentacles, around their mouths.

Others are filter feeders that sift tiny plants and animals out of the water.

Phylum Chordata (kor-dah-tah)

Chordates

The Phylum Chordata spans life forms from the blob-like sea squirts to

fishes, whales, seals, sea otters and humans. These animals have three features in common at some stage in their life cycles: gill slits, a spinal cord,

and a supporting notochord, or type of backbone.

In vertebrates, notochords develop during the embryonic stages and evolve into a full spinal column. In the sea squirts, the notochord disappears as

they assume their adult shapes.

Not all of the species in this phylum are vertebrates—animals with backbones. Some animals come close to having a backbone, but do not quite

make it—vertebrates comprise only one of the three chordate subphyla, the Vertebrata. Vertebrates have a notochord during the larval or embryonic

state. This then develops into a full spinal column. In the urochordates (sea

squirts), the notochord is present only in the larva and it disappears as the animal develops into an adult. In the cephalochordates (lancelets), the

notochord retains throughout the life of the animal.

Class Ascidiacea Sea Squirts

Sea squirts can be solitary or live in complex colonies. Immature, tadpole like sea squirts possess a nerve cord, a notochord and gill slits— all the

hallmarks of the Phylum Chordata.

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After their short larval lives, the tiny larva settle down on the sea bottom

using their adhesive organs to attach themselves to rocks and other hard surfaces. They then reabsorb their tails, notochords and nerve cords and

rearrange their internal organs—the sea squirt changes from a freeswimming tadpole like organism into a bloblike creature encased in a

leathery sac, called a tunic.

Water flows into the taller of sea squirts‘ two siphons or ―holes‖. Tiny plankton is filtered from the circulating water via a fine, netlike sac inside

the animal before it is expelled from the ―shorter‖ opening.

Phylum Platyhelminthes (plat-ee-hell-min-thees)

Flatworms

Commonly called flatworms, members of the Phylum Playhelminthes are

unsegmented and have no appendages. They are the type of animals that

are bilaterally symmetrical—their modest organ system is arranged in two equal parts along a central line.

The flukes and tapeworms comprise two very specialized

classes of flatworms which are entirely parasitic. The third class contains the turbellarians which are primarily free-

living marine animals. Most flatworms have two, four or six eyes that merely detect light, which they tend to avoid.

Most flatworms are bottom dwellers, living in the sand or in mud under rocks

and algae. Microscopic species live among sand grains on the beach. These

minute marine worms glide along a mucous trail propelled by undulating muscular contractions or by hairlike cilia located on their undersides.

Unlike the cnidarians, flatworms do not have a separate oral and anal

opening—food and waste both enter and exit through the same orifice. These worms feed on small invertebrates and dead animal matter. Small

food is swallowed whole through the pharynx—an extendible tube ending with the mouth—and digested in the gut. When flatworms feed on larger

corpses, some digestive enzymes are released through the pharynx to break

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down the food. The resulting mix is then swallowed and the digestion is

completed in the gut.

Flatworms reproduce both sexually and asexually. Sexual reproduction starts with two animals fertilizing each other—each animal is hermaphroditic and

carries both male and female sex organs. Their fertilized eggs are then released into the ocean. To reproduce asexually, flatworms split in two. Their

front and back halves form new worms.

Phylum Nemertea (nem-er-tee-ah) Nemerteans

Nermerteans are elongated worms with flattened bodies and spatula-like heads. They are commonly called ribbon worms because of

their shape. Most of these worms are marine, but a few species do inhabit fresh water and still others colonize

terrestrial habitats. Although nemerteans have no appendages and no segments, they are structurally more

complex than flatworms and as a consequence are able to grow larger.

Ribbon worms have a closed circulatory system and tubular

alimentary canal, a passage through the body from mouth to anus in which

food is received, digested and waste is excreted. Nemerteans also have light-detecting eye spots on the underside of their heads, near their slitlike

mouths.

Nemerteans have a unique proboscis, which has lead to another of their common names, proboscis worms. Their proboscises are long, tonguelike

organs that shoot out of their bodies from a sac near their mouths. When discharged, the proboscises evert themselves and can extend far beyond

their bodies. They use their proboscises to defend themselves, burrow, and to capture prey. These missile-organs are not harmful to people.

Ribbon Worms

Ribbon worms dwell in the mud and sand, under rocks, on algae, or in mussel beds. They are usually most active at night and glide along surfaces

on a coating of slime that they produce as they move.

Their prey includes annelid worms, small molluscs, crustaceans and even

small fishes. Waiting until their prey approaches, ribbon worms shoot out an extendible proboscis and sink a venomous spike, called the stylet, into their

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quarry. They will occasionally attack, kill and swallow prey much larger than

themselves. When searching for food, a 20-centimetre-long worm may stretch out to more than one metre in length. If food is limited, ribbon

worms can stave off starvation by shrinking. Ribbon worms are very delicate and easily fall apart when handled, so be

extremely gentle if you must handle them. If the head breaks off with a section of the foregut, that part of the worm can usually regenerate the lost

portion.

Phylum Annelida (an-el-ee-dah);

Segmented Worms

Although most marine worms belong to the Phylum Annelida, terrestrial earthworms are probably more

familiar to most people. Another well-known class of true segmented worms is the leeches.

Marine or terrestrial, annelids are distinguished from

other kinds of worms by the rings around the trunks of their bodies. Each ring delineates a separate segment.

Their bodies begin with a head that contains a primitive brain, and end with a terminal segment that possesses

an anus. Between the two, each of many segments contains an identical set

of blood vessels, lateral nerves, and reproductive and excretory organs. As the worm grows, it adds new segments to the middle—the oldest segments

are located closer to their heads. In many species, the heads are frequently highly specialized with feathery food collectors, eyes, sensory tentacles and

sharp, hard jaws.

To move, worms contract their body segments in sequence, creating waves of muscular contractions. The small, paired bristles that protrude from each

segment of the dominant marine worms improve their grip as they inch themselves forward.

Clam Worms

Clam worms may or may not live in mucous-lined burrows in the sand, but all can quickly plow their ways through sand or crawl through spaces in

mussel beds. These worms move using their legs, called parapodia (par-ah-

PODE-ee-ah). The parapodia are attached to bristles that project in pairs from each segment of their bodies, which can grow as long as one metre.

Clam worms are scavengers and carnivores that seize their prey, including crustaceans and molluscs, with their sharp, formidable jaws.

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Tube Worms The featherlike tentacles that protrude from the top of the tubes of the tube

worms are used to breathe and to filter planktonic food from water.

These worms secrete the tubes they live in. When threatened, tube worms withdraw their tentacular crowns into their tube homes for protection. A few

species may seal the top of the tube with a trap-door-like operculum.

Other Marine Invertebrate Phyla

Lophophorates include moss animals, bryozoans and lampshells.

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Marine Invertebrates: Summary

In Wet Lab programs at the Vancouver Aquarium, we teach specifically

about four main invertebrate phyla. The phyla we focus on are Cnidaria, Echinodermata, Mollusca and Arthropoda. It is important to note that

members of these phyla are not strictly marine or aquatic, but may also be found on land.

Phylum Cnidaria (NYE-dar-ee-ah); ―cnid‖ = nettle; ―aria‖

Includes: Sea Anemones

Corals Sea Fans

Jellyfish

Beachwalkers encountering cnidarians (NYE-dar-ee-anz) often confuse them with plants. Sticky sea anemones (ah-NEM-aw-nees) and their soft sea pen

and jellyfish relatives resemble flowers, feathery quill pens and flying

saucers more than they do other animals. Internally, however, they all share the same basic structure. Each has a central cavity with a single opening

that acts as both mouth and anus. This opening is surrounded by a circular fringe of tentacles laced with sticky, stinging cells.

Phylum Mollusca (MOLL-us-ka); ―moll‖=soft

Includes: Sea Snails

Mussels Clams

Chitons Octopus

Squid

The molluscs are a diverse group of more than 100,000 species of living animals including clams, snails, limpets, sea slugs, octopuses, squids and

abalones. Most molluscs can be identified by three features: a large

muscular foot, hard shells they create to cover their soft bodies, and a toothed, rasping tongue, called a radula (rad-YOU-lah). Octopuses and

squids have deviated from the general mollusc body plan. In both of these types of animals, the foot has evolved into a number of many-suckered

arms. Neither has a shell, but squids have a stiff internal rod, called a pen. Both octopuses and squids have a hard, bird-like beak which they use to bite

prey.

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Phylum Arthropoda (arth-ROE-poe-dah);

―arthro‖=jointed; ―poda‖=foot Includes:

Crabs Hermit Crabs

Barnacles Shrimps

Hermit crabs, crabs, barnacles and shrimps belong to the most abundant

animal group on Earth, the arthropods (arth-ROE-pawds). Including their land-based insect relatives, these animals comprise

approximately 80 percent of all living species on land, air and water. The common features of this group include jointed legs and a hard external shell,

or exoskeleton (x-OH-skeleton), which covers the three main parts of their

bodies—head, thorax and abdomen. As they grow, arthropods shed their hard external shells and make bigger new ones.

Phylum Echinodermata; (ee-KYE-noh-der-mah-tah); ―echino‖= spiny; ―dermata‖= skin

Includes: Sea Stars

Sea Urchins Sea Cucumbers

Sand Dollars

Sea stars, sea urchins, sea cucumbers and other related spiny-skinned invertebrates share a basic body plan of five identical sections that surround

a central mouth. Most echinoderms (ee-KYE-noh-derms) can move and

manipulate food by extending or contracting hundreds of tiny, muscle-bound cylinders of water, called tube feet. Sea stars also owe their formidable

staying power to these suction-tipped tube feet, which you will have experienced if you have ever tried removing one of these animals from a

rock.

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Fishes

First off, is it fish or is it fishes? In fact, it is both: fish refers to any number of

the same species i.e. singular and plural, whereas fishes refers to more

than one species of fish.

What is a Fish?

In simple terms, fishes are finned, aquatic vertebrates (animals with backbones) with gills. Most have scales. The first vertebrates, fishes

probably evolved from the same invertebrate ancestors as tunicates and other chordates about 500 million years ago. Today we know that fishes are

a large complex group with more than 20,000 species – as many as all the other classes of vertebrates put together.

Ranging in size from a half-inch-long goby to the 45-foot-long whale shark,

fishes dominate the world‘s waters. They are varied enough to thrive in the deep, cold abyss to a shallow, sun-warmed tide pool.

All fishes share the challenges of living in water; it affects all their vital

functions (feeding, respiration and reproduction). Every move a fish makes – exploring, fleeing enemies, migrating, mating – must be accomplished in a

medium 800 times denser than air.

Adaptations for Survival

Adaptation is defined as a characteristic (body part, behaviour, etc.) that

helps a plant or animal survive in its environment. Adaptations may be:

Structural - i.e. the shape of the tail fin of a fish Physiological – internal mechanisms - i.e. electric field produced by an

electric eel Behavioral – lifestyle - i.e. parental care in cichlids

Fish use these various types of adaptations to overcome the challenges of

survival in an aquatic environment. The major challenges for all living things are feeding and protection from predators and reproduction. For fish, many

of their survival adaptations focus on how they get around and how they

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maintain their position in the water in order to get their food and avoid

predation.

Swimming

Depending on where and how a fish lives, it will have evolved a specific body

type adapted to conditions in its environment. By looking at the body, you can learn more about a fish‘s lifestyle, of which a major part is how it swims.

A fish‘s swimming style depends on its shape and internal structure. To

move through water, a fish flexes its body, alternately contracting the series of muscles that lie on each side of the backbone. The shape most people

think of when they think of a fish is streamlined and fusiform (torpedo-shaped).

Many fishes that spend most of the time swimming do have a torpedo

shaped body; it offers the least resistance to water moving past and concentrates the wave of flexure in the tail area. But fish bodies can vary

considerably. Eels and eel-like fishes have a ribbon-shaped body, which

lacks a well-developed tail fin, so they swim by passing waves of flexure down the entire body.

Other fish may be flattened side-to-side like surf perches and flatfishes;

flattened belly-to-back like skates and bat rays; globular like deep-sea anglerfishes, or almost any shape. What these fishes lose in streamlining,

they gain elsewhere, such as in maneuverability or concealment.

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Body Types

Fusiform(A cigar-shaped fish): The swiftest of all fishes. Powerful tails help these fish chase prey and avoid predators. Many live in the open ocean

and swim constantly.

Rod: These elongated, arrow-like fish ambush their prey. They remain motionless until a smaller fish swims by and then they lunge.

Depressed: Fish flattened top to bottom and use camouflage instead of

speed. They burrow into sand or mud and some change colours to match their surroundings.

Sphere(Ball-shaped, slow-moving fish): Some fish have the ability to fill a sac in the body with air or water, thereby becoming too large to

swallow.

Ribbon (Eel-shaped slow-moving fish): This shape allows them to move easily through rocks and crevices. This allows them to be secretive,

hiding from predators and ambushing prey.

Compressed: Fishes that are flattened from side to side. Many are found

in coral reefs. Their compressed bodies, which are very maneuverable, allow quick turning and darting in and out of hiding places.

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Fins

Another essential component of swimming is fins. Most fishes have pectoral, pelvic, dorsal, anal, and caudal (tail) fins. Various combinations of fin

location, size, and shape are closely associated with different body shapes.

Caudal fin: In most fishes, the caudal fin provides the main thrust used in swimming. You can learn how fast and how often a fish swims by looking at

its caudal fin. The fastest-swimming fishes, such as tuna, have a stiff quarter-moon shaped caudal fin. Fishes that swim most of the time have

forked tails, the deepest forks on the most active fishes. Deep-bodied fishes

(like the flatfishes) and most bottom-living fishes (like the cabezon and lingcod) have tails that are square, rounded, or only slightly forked,

indicating a lifestyle that doesn‘t involve continuous fast swimming.

Pectoral fins: Most fishes use pectoral fins for stability, maneuverability, turning and stopping. On bony fishes the pectoral fins are located on each

side just behind the lower gill cover. Fishes that hover pick food items from the substrate and often use pectoral fins to propel themselves. Other fishes,

like bat rays, use enlarged pectoral fins to glide in the water, and to excavate prey from soft bottoms.

Pelvic fins: On sharks and the more primitive bony fishes like salmon, the

pelvic fins are on the underside, toward the rear of the fish. These fins act as stabilizers. In more advanced fishes, the pelvic fins are farther forward. In

some bottom-living fishes (like the black-eyed goby and snailfish), pelvic fins

are modified to perch on or hold onto the substrate.

Dorsal and anal fins: These top and bottom fins provide stability while swimming. Dorsal and anal fins also help keep the body from rolling over

during turns or wobbling back and forth during straight swimming. In fast-swimming pelagic fishes, like tuna, part of each fin is often divided into

numerous finlets; these help break up turbulence that would slow the fish down. When fast swimming fishes speed up, the forward part of the dorsal

fin may fold down into a dorsal slot to reduce drag; the pectoral fins lie down in shallow pockets. A few fishes, like pipefishes, use dorsal and anal fins to

propel themselves.

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Flotation

A third component of how a fish swims is how well (or poorly) it floats. There are two major ways a fish can keep from sinking: dynamic lift or static lift.

Some fishes are heavier than water, and must swim to achieve dynamic lift

from outspread pectoral fins (i.e. sharks).

Static lift: Fishes that use static lift store low-density gas, fats or oils to make themselves buoyant. Most bony fishes have a gas-filled swimbladder,

which makes them weightless in water. Gas has the advantage of low density, but the disadvantage of changing volume and buoyancy with

changes in depth and water pressure. As depth increases, the water pressure increases. If a deep-sea rockfish is brought from deep water up to

the surface too quickly, the swimbladder expands greatly due to reduced water pressure, causing ruptures and generally death.

Sharks and some deep-sea fishes store fats and oils in their tissues to

achieve neutral buoyancy. Though these fats and oils aren‘t as light as gas, they also don‘t change volume, so the fish can move up and down with ease.

Some fishes use a combination of gas and oil to stay afloat.

Feeding

Once a fish has addressed the challenges of mobility, it needs to eat. Feeding is a crucial element of survival, which often drives the evolution of

many interesting adaptations.

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Fishes feed in a variety of ways; their jaws and body shapes reflect the

different methods.

Feeding Behaviour

Pursuing: These torpedo-shaped predators out-swim and devour fishes and

active invertebrates. Many are fast swimming pelagic fishes like tuna that rely heavily on sight to find prey.

Ambushing: Ambushers lie quietly on the bottom, waiting for prey to come

within range. They are often camouflaged, like halibut on sandy floors and

lingcod on rocky floors. Visual predators, they are quick, but are not long-distance swimmers.

Luring: Lurers don‘t swim well; they don‘t need to. Besides impressive

teeth, these fishes have a modified dorsal spine or chin barbel (often bioluminescent) that dangle lures in front of their mouths, to tempt prey.

Picking: Some surf perches are pickers. Highly maneuverable, they hover

above rocky or sandy floors and around pilings, preying on individual invertebrates.

Grubbing: Fishes like the English sole grub around in the mud and sand for

bottom-dwelling invertebrates. Since they rely more on feel, smell and taste than vision, they aren‘t hampered by cloudy water.

Sucking: A pipefish uses its tube-like snout and small mouth to ingest small invertebrates and plankton with a rapid intake of water, as if sucking on a

straw.

Filtering: These fish have sieve-like branches (gill rakers) on the gills that let them graze on plankton. Schools of anchovies swim through plankton-

rich surface waters, mouths open, filtering plankton.

In addition to specific feeding behaviors and specially adapted mouths, fishes may also exhibit additional physical traits that aid in finding dinner:

Appendages: ―Fishing lures‖ – Fleshy appendages may be used to lure prey

by mimicking a worm. This tactic is used by some slow-swimming bottom dwellers.

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Barbels: Slender, touch organs that extend from the chins

of some fishes, for touching and tasting the sand or mud for prey (e.g. catfish).

Bioluminescence: Flashlight fish have eye pockets containing billions of light

producing bacteria. The organ rotates creating a flashing effect to confuse predators. These fish live in deep water

and use the light to find food and to communicate.

Avoiding Predators

All fish are concerned with avoiding predators. Many fish live in an ecological niche somewhere in the middle of the food chain – eating plankton or small

fish and in turn being preyed upon by larger fish. Even predators like sharks, which are at the top of their aquatic food chain, need to be

concerned about predation from humans, so many adaptations have evolved to meet this inherent challenge of survival. Colour is one example of an anti-

predation adaptation:

Colour

Disruptive colouration: Spots and stripes break up the body shape of the fish to conceal them against their background.

False eyespots: The true eyes of some fish are hidden in a band of black

but near the tail are prominent ―false eyes‖. A predator may attack these instead of the real eyes, allowing the fish to escape in the opposite direction.

Warning: Some animals are so well protected with spines and

poison that their bold striped colouring is a warning for other species to stay away (e.g. lionfish). Some

non-poisonous animals use warning colours to protect themselves, pretending to be poisonous when they are not.

Advertising colour: Colouration can attract and advertise a special service. Cleaner fish eat parasites from other fish, so large fish recognize the

colouration and do not harm these useful fish.

Countershading: Many open ocean animals have dark backs and light bellies. Viewed from above, the animal blends with

the dark ocean waters beneath it; from below, predators have difficulty in distinguishing the light-bellied animal from the

bright surface waters above it.

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Camouflage: This form of colouration helps animals blend with their surroundings. Some fish, such as a flatfish, can change colour while others

resemble their environment.

Major Groups of Fishes

The three major groups of living fishes are the jawless fishes (Class

Agnatha), cartilaginous fishes (Class Chondrichthyes) and bony fishes (Class Osteichthyes).

Jawless fishes (Class Agnatha)

Lampreys and hagfishes, the simplest vertebrates, are eel-like fishes that

lack the paired fins and jaws common to most fishes. These jawless fishes

have internal skeletons made of cartilage, well-developed skulls and rasping teeth, which are set in a plate in the head. Because they have no jaws,

these fishes are scavengers and parasites. Examples of jawless fish include the Pacific lamprey, black hagfish, and Pacific hagfish. Pacific and black

hagfishes occur commonly in deep water and feed mainly on dead and dying fishes. Because they‘re blind, they rely mainly on smell to find food, often

crawling into their prey to eat it from the inside. Pacific lampreys spawn in fresh water and spend their adult life in the sea. Lampreys are parasites:

they attach themselves to a fish, rasp away the flesh and suck the blood.

Cartilaginous fishes (Class Chondrichthyes)

Sharks, skates, rays and ratfish (Chimaeras) belong to a subclass of the

cartilaginous (cartilage skeleton) fishes (class Chondrichthyes) called the elasmobranchs. They appeared more than 350 million years ago, 150 million

years before the first dinosaurs. About 800 elasmobranch species belong to this group. They are the oldest living jawed vertebrates. A number of

features set them apart from bony fishes.

Bony fishes (Class Osteichthyes)

This class contains at least 20,000 species, including carnivores, herbivores and omnivores. They come in an amazing variety of forms developed to cope

with an incredible number of habitats, environmental and biological conditions. A typical bony fish breathes through gills protected by external

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covers; it has a bony skeleton, scaly skin, paired pectoral and pelvic fins and

an air-filled, buoyancy-regulating swimbladder.

Adaptations of Cartilaginous Fishes

AquaFacts: Sharks

Sharks, skates and rays are found in all the oceans of the world. Many

characteristics set them apart from the bony fishes. Their skeletons are made of cartilage, not bone; they reproduce only by internal fertilization;

their sandpapery skin is covered with tooth-like dermal denticles, quite different from the scales covering most bony fishes. And unlike the bony

fishes, whose gills are covered, sharks have unprotected gill openings or slits – from five to seven pairs.

A shark also has paired fins that stand out from the body like hydroplanes.

All sharks are carnivores; the largest, the basking and whale sharks, are filter feeders, straining the water for food. Others, like the seven-gill,

leopard and blue sharks, use sharp teeth to prey on a wide range of fishes

and invertebrates. The white shark preys on fishes and marine mammals. Although some sharks will attack humans, shark attacks are rare, averaging

fewer than 30 a year since 1940. To judge by shark fishery statistics and the growing number of shark products sold, sharks have far more to fear from

people than people from sharks.

Many elasmobranchs have adaptations which are not only ancient but also exquisitely adapted to a predatory life in the sea. Their success can be

attributed to certain adaptive features, including unique solutions to the problems of buoyancy, respiration, feeding, salt balance, sensory systems

and reproduction.

Buoyancy: A huge liver containing large quantities of fats and oils increases a shark‘s buoyancy. Tail shape and fin position provide additional

lift.

Respiration: Most sharks, skates and rays have holes called spiracles in

front of their gill slits. The spiracles draw water into the gill chambers in skates and rays. In pelagic sharks like the white shark which ―ram‖ water

across their gills while swimming, the spiracles may be absent or reduced.

Feeding: Each species of elasmobranch has teeth that indicate how it makes a living. Some pelagic sharks, like the white shark, have triangular,

bladelike teeth to snap or saw off large chunks of their prey. Another pelagic shark, the blue shark, swallows its prey whole. Its teeth come to long, thin

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points to hold the prey until it can be swallowed. And bottom-living bat rays

have blunt, plate teeth, to crush the hard shells of clams and crabs.

Water/Salt balance: While bony fishes must excrete salts to avoid dehydration, sharks, skates and rays have a different system. They store

high levels of metabolic wastes (like urea) in their blood and tissue fluids. By making the sharks‘ body fluids as ―salty‖ as the sea, the stored wastes

prevent salt absorption and dehydration.

Sensory system: Most elasmobranchii have an acute sense of smell; they can also detect minute turbulence and vibrations with the inner ear and the

lateral line system. Most sharks‘ eyes are well adapted for vision at low light levels. They also have an electroreception system called the Ampullae of

Lorenzini that allows them to detect tiny electrical impulses created by the muscle movements of prey at close range.

Reproduction: Many elasmobranchs have reproductive systems nearly

as complex as mammals‘ in their care and sustenance of storage of

sperm. Sharks, skates and rays use one of these reproductive strategies:

Egg-laying - All skates and some sharks lay eggs. They package fertilized eggs in a special egg case,

which the female releases to develop outside her body. Each egg is supplied with a large yolk to nourish the

developing embryo. (Big skates and ratfish use this method.)

Live-bearing - All rays and most sharks bear live young retaining the

developing eggs and protecting them inside the body as they develop. There

are three ways livebearers nourish their young: by yolk sacs, like spiny dogfish and leopard sharks

by yolk sacs, then through a mammal-like placenta, like blue sharks by yolk sacs, then through uterine secretions, like bat rays.

In each case, the young are born ready to swim and feed on their own.

Pelagic sharks

The best illustration of adaptations for a pelagic and predatory lifestyle is the family Lamnidae, which includes the white, mako and salmon sharks. Their

adaptations for high-speed swimming include conical snout, fusiform streamlined body, very small second dorsal fin, caudal peduncle flattened

top to bottom to form keels on both sides that help strengthen the tail,

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lunate tail with two nearly symmetrical lobes and very large gills for more

efficient gas exchange.

In addition to these adaptations, some members of this family, like the white shark, are able to maintain a body temperature 100-180 F (70-100 C) above

the temperature of the surrounding water. This increased temperature is accomplished through a highly developed system of counter-current heat

exchange in the circulatory system. This system prevents heat from escaping as blood circulates through the gills and near the body surface.

Warm muscles are able to contract more rapidly than cold muscles; an elevated body temperature allows muscles to move (work) faster, enabling

the shark to attain greater swimming speed.

Such adaptations for high-speed swimming allow these sharks to feed on fast-moving predators such as other sharks, pelagic fishes and marine

mammals. This puts them at the top of marine food chains.

Adaptations of Bony Fishes

Class Osteichthyes is the largest class of vertebrates with nearly 30 000 species. Unlike the cartilaginous fishes, bony fishes have stiff skeletons that

contain calcium salts. Most bony fish have fins with thin, flexible skeletal rays. Fish that do not have rays in their fins are called lobe-finned fish, and

have muscular fins supported by bones. Only one species of lobe-finned fish, the coelacanth, still lives; however, lobe-finned fish are an important group

because they have been thought to be the branch of aquatic animals to initially colonize terrestrial environments.

Bony fishes have the following special adaptations for survival:

Sight and hearing: Water is much murkier than air, but many fishes can see well. Some deep-sea fishes (like lantern fishes) have large eyes,

superbly adapted for seeing in dim surroundings. (Some abyssal fishes don‘t need eyes and have lost them.) Sound travels very well in water, and fishes

have a well-developed sense of hearing.

Smell and touch: Odors diffuse slowly in water, but many fishes smell food or enemies. Sharks can smell minute quantities of blood in the water

over many kilometres. When returning to spawn, salmon may use odors to help find the creek where they were born. Fishes also have a well-developed

sense of touch. It helps them breed, escape predators and orient themselves to their surroundings.

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Lateral line system: Fishes have gained a sense of ―distant touch‖

through the lateral line organs. The lateral line consists of a series of pores containing pressure-sensitive hair receptors. A fish uses the lateral line

mainly for prompt, short-range detection of disturbances in the water, such as those caused by moving predators and prey.

Respiration: Like all animals, fishes need oxygen to carry out their

metabolic tasks. Getting it poses a problem, since the ocean contains only about 1/30 the oxygen in air. In most cases, the solution to this problem is

gills, which have large surface areas and are extremely efficient at gas exchange. The gills consist of bony or cartilaginous arches which anchor

pairs of gill filaments. Numerous, minute leaf-like structures protrude from both sides of each filament. Each leaf-like structure has a thin membrane

where oxygen is taken up and carbon dioxide is given off. Water travels across the gill surfaces in the opposite direction of the blood within the gills.

This countercurrent system makes gas exchange more efficient. The oxygen

diffuses from the area of high concentration (water) to the area of low concentration (blood). Some fishes can extract 80% of the incoming water‘s

oxygen. In most cases, water is actively pumped over the gills by the mouth

muscles. However, some fast fishes, like tunas, simply swim with their mouths open, ram-jetting water through the gills.

Water / salt balance: Because a bony fish‘s body tissues aren‘t as salty

as the seawater, they tend to lose water and absorb salt. To avoid dehydration, the fish must keep drinking seawater and excreting salts. In

freshwater fish, it is the opposite: a freshwater fish must excrete a lot of water and concentrate salts.

Reproduction:

Broadcasting: Most marine fishes, like mackerel and sardines, release sperm and eggs into the water where fertilization and development occur

without further parental involvement. These broadcasters can produce thousands to millions of eggs annually. If all these eggs developed into

mature adults, the oceans would soon be choked with fish. But most are eaten or die of other causes long before adulthood. The strategy is to

produce such overwhelming numbers of offspring that some are sure to survive. Some broadcast eggs, like anchovy and sardine eggs, are less

dense than seawater and drift about in the plankton. Others are denser than seawater and sink to the bottom to develop. Some, like topsmelt eggs, are

held to the substrate by slender tentacle-like tendrils.

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Nest-building: Some marine fishes prepare a nest or protected area in

which they deposit fertilized eggs. The Plainfin Midshipman is a nest-builder. Each summer the males migrate to the intertidal from deep water offshore,

choose a site under a rock, and begin to hum. The humming attracts a female midshipman to lay eggs on the underside of the rock; the male stays

behind to guard the developing embryos. Other nest-builders include sticklebacks, lingcod and fringeheads.

Brooding: Some species have a special brooding area on the body to

protect developing embryos. A female pipefish lays her eggs in a special pouch on the male‘s belly. He fertilizes the eggs and broods them, out of

harm‘s way. The young stay in the pouch until they wriggle out as fully formed juveniles.

Live-bearing: Surf perches are live-bearers: the male inseminates the

female by means of a specialized portion of the anal fin, and the fertilized

eggs stay in the female‘s ovary to develop into miniature versions of the adults. Developing embryos are nourished by a nutrient-rich secretion they

absorb through their enlarged fins. The males of some surf perches can reproduce as soon as they‘re born. Rockfish eggs are fertilized internally,

too, but the female releases the larvae soon after they hatch in the body cavity.

Avoiding Predators

Armour: Most fishes have scales to protect the skin from abrasions and

bites. Some fishes, like sturgeons, have large, bony plates of armour (scutes). The stonefish is protected by venomous dorsal spines.

Countershading: Fishes that live in open water often have dark backs that

grade into light silver or white undersides. With this countershading, a fish tends to blend into the background in water. A predator looking down may

not see the fish‘s dark back against the dark depths; a predator looking up may not see the fish‘s light underside against the light from the surface.

From the side, light catching the fish‘s back gives it the same tone as the flanks and underside, which are shaded from sunlight. Because

countershading is a protective response to the play of light around and on fishes, it is particularly characteristic of fishes living close to the surface.

Disruptive colouration: Many fishes that live on or near the bottom, display

something like the camouflage on battle fatigues. The natural outline of the

fish seems to be broken up by bands, spots or patches of pigment that contrast strongly with the colour of the rest of the skin. The disruptive

markings draw the observer‘s gaze, diverting it from the fish as a whole.

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Typically, the pattern masks the eye, and ―eye-spots‖ on the body or median

fins can lead predators to attack at a less vital spot, away from the head. Local species with disruptive colouration include painted greenlings, which

have dark bands, big skates, which are marked with false eyespots and sailfins which have a prominent eyestripe.

Deceptive resemblance: Many fishes are able to change their colour and

pattern to match the background around them. They do this by expanding and contracting colour cells. The master of this form of disguise is the sand

dab, which can almost perfectly match the colour and pattern of its background. (A few flatfish species can even match a miniature

checkerboard pattern). Some sculpins, like the cabezon, are also adept at camouflage. Another example would be pipefishes which align themselves

with blades of eelgrass, so it‘s hard to tell fish from plant. In the same way, the giant kelpfish closely resembles the kelp blades among which it lives.

Schooling: Some species of fish regularly gather in schools, or large groups of similar-sized individuals. They probably use visual cues and lateral line

―distant touch‖ to form and maintain schools. Some fishes, like sardines and anchovies, school throughout their lives, while others school only at certain

times (while they are juveniles or during migration or spawning season, for instance). And some fishes school only during a certain part of the day,

when they are in greatest danger of predation.

There are several current theories about how schooling helps prey avoid predators. Here are a few:

A close-packed school may look like a large organism and intimidate predators.

Some predators have a hard time choosing which fish in a school to attack, and go first for one fish, then for another, catching few.

A fish on the inside of the school has less chance of being eaten than a

fish on the outside. The odds that a predator will find a school of fish may be smaller than

the odds of finding an individual fish, as non-schooling individuals scatter about.

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Marine Mammals

AquaFacts: Marine Mammal Rescue and Rehabilitation Program Training Marine Mammals

What is a Mammal?

The mammals are one of the seven classes of vertebrates. Though there are 4,000 to 5,000 species of mammals, they add up to only about 9% of the

total number of vertebrate species. All mammals are warm-blooded, have

hair and nurse their offspring. And except for the egg-laying echidna and platypus, all mammals bear live young.

Fossil records show how certain mammalian characteristics began to develop

about 250 million years ago, when mammals diverged from reptiles. Mammals developed fewer skull bones and jawbones; their teeth became

specialized for various types of feeding and their skeleton changed to improve locomotion.

But perhaps the most significant difference between mammals and reptiles is

warm-bloodedness; this feature has allowed mammals to live in nearly every major environment on earth.

What is the Origin of Marine Mammals?

Mammals spent hundreds of millions of years evolving from aquatic into

terrestrial creatures; then some of them returned to the ocean. What did these marine mammals gain by moving back to the sea? Among the benefits

were: Access to new and abundant foods

Escape from terrestrial predators New areas (oceans and waterways) through which a species could

disperse

There are four groups of living marine mammals: cetaceans (whales, dolphins and porpoises), pinnipeds (seals, sea lions and fur seals) and then

sea otters and polar bears.

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We can tell how completely cetaceans, pinnipeds and sea otters have evolved into marine animals by how much their original terrestrial features

have changed. For example, the highly evolved whales have lost their hind limbs, while the recently evolved sea otter has retained them.

Marine Mammal Adaptations

Evolution has transformed the basic land mammal into creatures beautifully

adapted to life in the ocean. Their adaptations enable them to swim, dive, breathe, keep warm and find fresh water and food in cold, dark and hostile

saltwater seas.

Hydrodynamics and Body Structure

When swimmers move through the water, they must overcome the problem of ―drag‖ or resistance. Drag occurs when layers of water surrounding the

swimmer move past one another and over the swimmer with different speeds, pressures and patterns. These differences create frictional drag,

wave drag and pressure drag. A long, slender, streamlined body (like that of an eel) will reduce pressure drag. But it takes a short, plump body to reduce

frictional drag. So the ideal shape for moving through water is a compromise between short/plump and long/slender, spindle- or torpedo-shape. A

spindle-shaped body is circular in cross-section and thickest near the centre of its length, like the body of a dolphin.

Body Streamlining and Smoothing

Marine mammals have further reduced drag by eliminating or remodeling body parts that cause extra drag. Some of these adaptations are:

External ears that vary from small to nonexistent Sex organs and mammary glands that retract into the body contour

when not in use Testes that have moved back into the abdomen

Limbs and feet that have vanished or changed into flippers New body parts, such as fins and flukes, to help stabilize and propel

the swimmer

A sleek body surface also helps reduce drag. When seals, sea lions and

otters swim, their hair lies flat so they can pass smoothly through the water. Beneath a dolphin‘s smooth skin, a spongy layer of tissue absorbs

turbulence.

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A small cetacean has the most hydro-dynamically perfect

body of any animal. The neck vertebrae are compressed (eliminating a long, wobbly neck); the thorax and body

muscles have been molded into a torpedo shape and a layer of fat smoothes and fills in the uneven spots.

Keeping Warm

Marine mammals have evolved ways to stay warm in cold water, which draws away heat 20 to 25 times faster than does air. A large appetite and

rapid digestion provide the calories to fuel the high metabolic rates, which

produce heat. Heat loss is minimized by the insulation of fur and/or blubber, reduced peripheral circulation with countercurrent heat exchange, compact

shape and, in many marine mammals, large size.

Diving Adaptations

Changes in the circulatory and respiratory systems

ensure that the body is supplied with sufficient oxygen and can withstand water pressure during a

dive. Other adaptations enable marine mammals to dive for long periods of time: the heartbeat slows down (bradycardia); blood

is sent only to essential tissues and organs; carbon dioxide build-up is tolerated; the lungs collapse, forcing air into nonabsorbent pockets;

metabolism and body temperature decrease; myoglobin in the muscles releases its stored oxygen; and high levels of lactic acid, which accumulates

in the muscles, are tolerated.

Finding Fresh Water

Marine mammals have the same problems as desert mammals when it comes to finding fresh water to drink—there isn‘t any. Marine mammals deal

with this problem in several ways: They derive some water from their prey, particularly from fishes (the

fish have already filtered their water!) They drink sea water, but have extremely efficient kidneys which

extract the salt from the blood and excrete it in a highly concentrated

urine Mothers guard against water loss while nursing by producing a very

concentrated milk (50% fat; the baby metabolizes the fat to gain water)

They metabolize fat reserves (like gray whales on migration), deriving metabolic water

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They breathe less and so lose less water in expired air

They don‘t perspire

Feeding Adaptations

Marine mammals have several adaptations for feeding, including excellent

underwater vision. Toothed whales also have a sonar-type system called echolocation. Teeth, baleen, cooperative hunting and

feeding, tool-using ability (sea otters using a rock to crack a shell) and blowing ―bubble nets‖ to surround

prey are only a few of the structural and behavioral

adaptations that have allowed various marine mammals to successfully exploit the food resources of the sea.

Cetaceans

AquaFacts: Whales in Aquariums

What is a cetacean?

The cetaceans [whales, dolphins and porpoises: order Cetacea (seh-TAY-she-ah)] are the most highly adapted marine mammals; they re-entered the

sea more than forty million years ago. Though they may have evolved from

cow- or goat-like ancestors, cetaceans‘ physiology and morphology (body structure) have become highly modified for life in a dense, cold, watery

medium. Most are fast-swimming predators with many adaptations for finding and capturing their prey (fishes, squids or other marine mammals).

Many dive to great depths and hold their breath for a long time. They maintain a high metabolic rate and a stable warm core temperature, and

they mate, give birth and nurse their young in the water. Indeed, cetaceans are so well adapted to life in the sea that they are completely helpless on

land, and nearly always die if stranded there.

Two Groups of Whales

There are two groups of cetaceans: the toothed whales (Odontoceti) and the baleen whales (Mysticeti). The toothed whales (sperm whales, orcas,

belugas, dolphins and porpoises) have teeth as adults and a single blowhole. Some toothed whale species are gregarious and have highly structured

societies; they sometimes swim in groups of hundreds of animals.

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An adult baleen whale does not have teeth. Instead, it has a series of long,

horny baleen plates that hang from the gum line on either side of the upper jaw. (They are made of keratin, a material much like our fingernails.) Baleen

whales swim alone or in small groups and do not live in highly organized societies as many toothed whales do.

SUBORDER ODONTOCETES—TOOTHED WHALES

(oh-DOHN-toh-seets; ―odotes‖= toothed; ―cetes‖= whales)

Toothed whales have teeth—and their teeth can grow to

mythical proportions, as in the case of the spiraling, unicorn-like tusks of male narwhals. Or they may only appear for a short period before birth as in

the case of female narwhals.

The dental arrangements of the Odontocetes are dictated by their feeding

habits which are extremely varied. Their diets range from shrimps, squids and schooling fishes to marine birds, seals, sea lions and even other whales.

Killer whales have sharp, conical teeth to grasp fast-swimming fishes and other marine mammals. Beluga whales have flatter, pegshaped teeth suited

for capturing small fishes and grinding up crustaceans.

Toothed whales swim in every ocean on Earth and come in all sizes. Sperm whales descend into deep-ocean valleys, while the Amazon River dolphins

swim up freshwater rivers. Male sperm whales may reach 44 tonnes and 18 metres in length, while tiny harbour porpoises only grow to 90 kilograms and

2 metres in length. Odontocetes have a single blowhole, instead of the two that baleen whales have. The internal nasal passage of all whales‘ blowholes

are divided in two separate parts by a single septum.

SUBORDER MYSTICETES—BALEEN WHALES

(mis-TEH-seets; ―mysti‖=moustache, ―cetes‖= whales)

Baleen whales are also called Mysticetes (mis-TEH-seets), or moustache whales, because of the way they feed. Baleen whales

use stiff, fringed brushes of baleen suspended from the roofs of their mouths to strain small schooling fishes, krill and other plankton out of the water.

Baleen is made from keratin, the same material as our hair and finger nails.

The long, wide bristles of the baleen plates intertwine to form a matted sieve. The length, density, flexibility and size of the bristles are related to

the targeted prey of each species. Bowhead whales use fine, dense fringes of baleen to strain minute planktonic animals from the mid-water column. Gray

whales force seafloor mud through their coarse bristles to sift out the small,

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sea bottom animals they feed on.

The largest of all living animals are the blue whales. Blue whales reach

lengths of 30 metres and weigh more than 160 tonnes, the same weight as nearly 2,000 adult humans! If these titans lived on land, their enormous

mass would cause them to collapse inward, crushing their internal organs. Surprisingly, the diet of this marine giant is almost completely made up of

tiny shrimplike animals called krill—mere five-centimetre-long crustaceans.

Baleen whales breathe through two blowholes and not one, as the toothed whales do. When baleen whales exhale, they form two columns of vapor

which usually combine to create a single spout.

While there are differences between toothed and baleen whales, their shared ancestry and oceanic way of life give them much in common.

Cetacean Adaptations Because seawater is 800 times as dense as air and draws heat from a warm

body faster than air of the same temperature, it poses serious problems for a warm-blooded, air-breathing mammal. The body shape adaptations of

cetaceans make them look almost like fishes. The body is fusiform; the neck is so short, it‘s nonexistent; the forelimbs have become finlike flippers; the

hind limbs are gone (but vestigial hip bones may remain) and the tip of the tail has been expanded into a horizontal fluke, something like the caudal fin

of a fish.

Cetaceans have little or no hair; the smooth skin passes through water with minimal turbulence. Genital organs and mammary glands have been

withdrawn into the body wall for streamlining. External ears have been

reduced to pinholes. Nostrils are on the top of the head, allowing the animal to breathe at the surface while swimming and the layer of blubber beneath

the skin smoothes body contours. While sight may still be important, smell isn‘t. New senses involving sound and echolocation, however, are important

in communication, navigation and food gathering.

Conserving Heat

Besides relying on a thick layer of blubber, cetaceans cut down on heat loss

by controlling circulation to their extremities (flukes and flippers). A system

of countercurrent heat exchange works to conserve heat in the core of the animal. Because cetaceans extract oxygen from inhaled air with greater

efficiency than land mammals, they can breathe less frequently, decreasing

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heat loss when they exhale. Often their migration strategies ensure that

newborn animals enter the world in warm water where temperature shock and heat loss is minimized. Here they grow rapidly on mother‘s milk and

thicken their blubber before migrating with their mothers to the rich (but cold) feeding grounds in temperate and polar regions.

Breathing

Unlike their terrestrial ancestors, whales must consciously breathe. Their

blowholes are closed by nasal plugs, which they open with muscles to take in air. These muscles raise the lips that surround their blowholes, deflecting

water away when they inhale. Whales replace 80 to 90 percent of the air in their lungs with each breath—a much greater exchange of air than terrestrial

animals are capable of achieving. Some species of whales use this air in underwater dives of up to an hour or more at a time.

Whales always inhale and exhale air using their blowholes—they cannot breathe through their

mouths, as the trachea that leads to their lungs and the esophagus that leads to their stomach are

completely separate. (Water swallowed by a whale enters its stomach. If water enters the lungs, the

whale will drown.) Whales do not exhale water, although their telltale spouts do make it appear that way. Some whales can be identified by the shape

and size of their spout.

Swimming and Diving Physiology

They swim by pumping their mighty tails up and down—and not from side to side as fishes do. Like fishes, they use their front flippers, or

fins, to steer. Whales swim far below the ocean surfaces, withstanding the immense pressures of the deep. Sperm whales can plunge as deep as 3,000

metres into the ocean in search of their main prey, squids.

When human divers use scuba and breathe under water, the increased pressure forces more than the usual amount of nitrogen into the blood.

Returning to the surface too rapidly results in nitrogen bubbles in the blood—the bends. In addition, breathing nitrogen in air under pressure

causes a state of drunkenness called ―nitrogen narcosis‖ or ―rapture of the deep‖.

A human being that dives with only one breath will pass out after about three minutes without oxygen, but a sperm whale can dive for as long as 90

minutes and a bottlenose whale can stay under water for two hours. In

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diving mammals, oxygen is stored in myoglobin in the muscles, so it isn‘t

necessary to descend with air in the lungs (which would absorb the excess nitrogen).

In marine mammals, the ribs ―float‖; that is, they don‘t form a rigid ribcage

with extensive cartilaginous connections. As a result, as the animal dives deeper and pressures increase, the lungs collapse and the thorax literally

caves in. All the air in the lungs is shunted or diverted to the large upper respiratory passages where there is no gas exchange. This is why marine

mammals dive after they exhale, and why their relative lung volume is no larger than that of land mammals. Indeed in whales, the lung volume is

considerably smaller (2.5% compared to 7.7% in humans).

Where is oxygen carried during the dive? Some oxygen is in the circulating blood (there‘s more blood, containing larger red blood cells, which contain

more hemoglobin with a higher affinity for oxygen than in land mammals).

The blood serves only the vital organs (heart and brain) during the dive (peripheral circulation shuts down), and a great deal of oxygen bound to

myoglobin is already in the muscles where it will be available when needed. Myoglobin is the oxygen-carrying pigment in the muscles.

Cetacean Senses

Most cetaceans see well, although most lack three-dimensional vision (the eyes are on the sides of the head and don‘t see forward very well). Whales

spy hop, raising their eyes above the water‘s surface to see what is

happening above water. A continuous stream of mucus flows over marine mammals‘ eyes to protect them from foreign particles and objects and to

enable them to see clearly under water.

The sense of touch is keen and many toothed whales engage in a great deal of intra-specific caressing, nudging and even non-aggressive biting.

Cetaceans probably don‘t taste well or smell at all. Their hearing, however, is phenomenally well developed.

Water conducts sound four times faster than air and it‘s a good medium for

transmitting and receiving sound. Mysticetes use mostly low-frequency sounds for communication, sometimes across very long distances (i.e., the

songs of the humpback whales). Odontocetes have a large and complex vocal repertoire and use mostly high frequencies, some of them higher than

the range of human hearing. Only odontocetes are known to echolocate.

Echolocating—seeing with sound: Even though whales have excellent vision

underwater, they can still have difficulty seeing far. Cloudy waters frequently

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reduce visibility and, of course, the moon does not provide enough light to

guide them under night skies and sunlight cannot penetrate through very thickly-iced waters.

To overcome these challenges, toothed whales ―see‖ using sound—they use a highly sophisticated form of sonar, called echolocation. Toothed whales

produce clicking sounds from small air sacs in their nasal passages that travel through the water and bounce back, off objects. From these echoes,

whales can detect where the object is, what shape it is, and how fast it is moving. Some scientists believe that killer whales have ―acoustic maps‖ of

locations well-known to them stored in their memories. Bowhead whales have a primitive echolocation system. Scientists have yet to discover if they

use it to sense their surroundings.

Communicating

In addition to using sound for locating food and identifying their surroundings, cetaceans, or whales, use squeaks, clicks, whistles and cries

to communicate, sometimes over long distances. Some whale sounds travel thousands of kilometres under water. Although scientists still have little idea

what the whales are saying, they can identify discrete killer whale dialects, for example, and can tell what the whales are doing—resting whales use

different calls than socializing or foraging whales do. Apart from humans, killer whales are the only animals that maintain separate dialects—calls

usually only differ when there is a geographic separation in a species‘ range. These various sounds are produced in the head, by squeezing air

from one nasal air sac to another – the blowhole does not play a role in

sound production. The sound waves are then reflected off the skull and concentrated by the fatty ―melon‖ before being beamed out into the water.

All cetaceans hear extremely well. Sound is received through the lower jawbones and transmitted to the hearing apparatus of the middle ear. The

middle ear bones of cetaceans are separate from the skull (they touch the skull in land mammals) so they don‘t pick up sound through the skull. If they

did, cetaceans wouldn‘t be able to determine the direction from which the sound arrived.

Colour and Pattern

Cetaceans, like pelagic fishes, are generally light-coloured on the underside

and dark-coloured above—they are counter-shaded. This makes them less visible to both predators and prey. In addition, irregular blotches of colour

(gray whale) or distinctive, regular light patches and bands (orca, Pacific white-sided dolphin, Dall‘s porpoise) may help to disrupt the body outline or

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may serve as focal points for other individuals in schooling or locating

genitals, nipples, etc.

The Killer Whale case study gives you further information on the lifestyle of toothed whales, specifically killer whales. Although the Aquarium no longer

has any killer whales on display, this species has played a central role in the history of the Aquarium, and continues to be studied in Aquarium research

projects in the wild. Killer whales are also a key area of conservation focus for the Aquarium, as demonstrated by our B.C Cetacaen Sightings Network

and Killer Whale Adoption Programs.

Breeding

Many cetaceans and pinnipeds (seals and sea lions) make long annual migrations between winter breeding and birthing grounds in warm waters

and summer feeding grounds in temperate and polar latitudes. After impregnation it will be about a year until the pregnant female returns to the

safe warm breeding grounds to give birth. However, prenatal development often takes less than a year. So that the calf is not born in an inappropriate

location, some marine animals delay implantation of the fertilized egg for weeks or months. After implantation in the uterine wall, the embryo is

nourished by the placental connection to the mother. This is all timed so that the fetus will be near term just when the mother gets back to the

appropriate birthing grounds one year after conception.

Like all mammals, whales give birth to live young. Female whales usually

give birth to one calf at a time. The newborns usually emerge tail first underwater, surfacing to take their first breath. Survival rates of calves vary

among species. Forty percent of killer whale calves die shortly after birth from unknown causes.

While few whale births have been seen in the wild, a number have been

observed in aquariums—and much has been learned from these births. Ultrasounds performed at the Vancouver Aquarium on the pregnant killer

whale, Bjossa (bee-YOH-sah), revealed how killer whale fetuses develop. Marine mammal staff collected urine samples daily as part of their routine

animal husbandry practices to measure changes in Bjossa‘s hormonal levels. These levels showed that Bjossa‘s pregnancy was much longer than had

previously been thought based on studies of wild populations. Breeding in aquariums has been identified by international conservation organizations,

including the World Wildlife Fund and the International Union for the

Conservation of Nature, as perhaps the only hope for a number of endangered dolphins and porpoises. Animal care skills acquired in aquariums

with non-endangered species are critical to the success of this program.

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Marine Mammal Orders

Seals, Sea Lions, Walruses, Sea Otters and Polar Bears

ORDER CARNIVORA

Most members of the Order Carnivora are terrestrial. The marine branch of the order is specialized for life at sea, while retaining the four limbs of their

land ancestors. Seals, sea lions, walruses, sea otters and polar bears, like all carnivores, are predatory animals that have developed a great variety of

hunting strategies. These marine predators have sharp teeth adapted for stabbing, tearing, and eating prey. Most carnivores have keen senses of

smell and many have powerful tails, which they use in the pursuit of their prey.

Walruses and seals are pinnipeds (pin-NI-peds; pin meaning feather; ped

means foot), members of the Sub-Order Pinnipedia (of which there are 3 families). Walruses are one of the largest pinnipeds and are distinguished

from their close relatives by their powerful tusks, beards and watery,

bloodshot eyes.

Scientists divide the seals into two groups, the eared (Family Phocidae)

and earless seals (Family Otariidae). Harbour seals are earless seals,

which are also known as true seals. Stellar Sea lions are eared seals.

Earless seals lack an external ear flap, but can still have acute hearing. These seals swim like fishes—they move the tail ends of their bodies from

side to side and steer with their short, front flippers. Their small foreflippers cannot support the animals‘ weights on land, so they flop about on their

stomachs when on shore. Earless seals can be very small or very large— ringed seals are 1.5-metres long and weigh 68 kilograms, while elephant

seals are 5 metres in length and weigh in at 3.6 tonnes.

Ringed seals and other true seals grow an outer coat of one-centimetrelong stiff hairs over a flat-haired underfur layer that is half as long. This fur is not

waterproof, and when swimming, these seals become wet to the skin. These

seals use their fat to insulate themselves in cold waters.

Eared seals can be identified by small, external ear flaps. Unlike their earless relatives, eared seals can move quickly on shore. These seals support their

weight on their long, paddle-shaped front flippers. Their flippers bend outward at the wrists while their hind flippers rotate forward and are tucked

underneath their bodies. Male eared seals are frequently much larger than females.

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Unlike whales, most seals and sea lions must ―haul out‖ on shore to moult, mate and all must give birth on land. Some species prefer to sleep on land

or on ice, safe from marine predators such as killer whales. A thick layer of insulating blubber, combined with a coarse fur coat, heats and protects their

streamlined bodies as they heave themselves across the sharp rocks, crags and ice floes of their haul out locations. Their skins produce oily secretions

that keep their coats lubricated and waterproofed. Fur seals have a layer of underfur which traps an insulating layer of air in it, keeping their skin dry.

The polar bear (Family Ursidae) and the sea otter (Family Mustelidae)

are the only marine members of two other families in the Order Carnivora. Polar bears, like most of their bear relatives, are good climbers.

Unlike most other bears, polar bears do not hibernate. Like most bears, polar bears live solitary lives except during the breeding season.

Dolphins, Toothed Whales, Baleen Whales

ORDER CETACEA

SUBORDER MYSTICETES—BALEEN WHALES

Bowhead Whales Bowhead whales, named after their backs

which are said to resemble musicians‘ bows, are the only species of baleen

whale that lives in the Arctic Ocean all year. Bowheads undertake short seasonal

migrations hovering near the edge of solid pack ice, heading north in the summer and south in the winter. These

enormous animals are well suited to this icy habitat. Their 90-tonne bodies are encased in thick 70-centimetre-wide walls of blubber.

They lack dorsal fins and can use their backs to break open breathing holes in ice up to 30-centimetres thick. These white-chinned, bluish-skinned

whales are believed to dive as deep as 200 metres, feeding mainly on krill located at or below the water‘s surface, and possibly on the sea floor. These

whales can be very playful and have been seen tossing logs the size of

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telephone poles. Bowhead whales are endangered. Arctic populations once

numbered more than 50,000 animals, but whalers severely depleted these stocks in the nineteenth century. There are now between 6,000 to 12,000

bowheads.

Grey Whales AquaFacts: Grey Whales

SUBORDER ODONTOCETES—TOOTHED WHALES

AquaFacts: Dolphins and Porpoises

Belugas Pacific White Sided Dolphin

Killer Whales

Narwhals Narwhals are mottled

whales similar in size and shape to their close

relatives, the belugas. Male narwhals grow a

single long, spiraling tooth, or tusk. They joust by crossing their tusks together, above and below

the water‘s surface. Older males are often deeply scarred from these at-sea duels. The lengths of the males‘ tusks define their social status. Adult female

narwhals are rarely visible.

Narwhals live farther north than almost any other whale and are found only

in Arctic waters. Their diet is mainly made up of Arctic cod, squids, octopuses and crustaceans. Hundreds of pods may join together for

traveling, with thousands of animals spread over many square kilometres. A pod of narwhals may consist of a mixed group of animals, but usually there

is segregation by age and sex. Females and calves form one group; juveniles and adult males form separate associations. These social mammals produce

a cacophony of clicks, chain-saw buzzes, squawks , blares and whistles to communicate and to echolocate.

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The Killer Whale —A Representative Toothed Whale

AquaFacts Killer Whales

The killer whale, or orca, Orcinus orca, is a

worldwide species and has become familiar to many people as the star attraction at many theme

parks and oceanariums. These large toothed whales are members of the dolphin family.

What’s in a name?

Although ―orca‖ is a popular name for this species,

it derives from the Latin name, Orcinus orca, that translates to ―demon

whale from Hell‖. The name was given to the species in a time when observers thought killer whales were fierce monsters that would attack

anything that moved, including humans, although attacks on human are exceptionally rare. The term ―killer whale‖ refers to the fact that this species

is the only cetacean that feeds on other whales, so it‘s a more biologically correct name to use.

Early studies of killer whale populations found distinct and familiar

characteristics in each group of whales. These groups of killer whales, or pods, usually contained 10 to 25 or more whales, and traveled within

predictable ranges and patterns up the Pacific coast. These became known as ―resident‖ killer whales. However, soon smaller groups of between two to

five killer whales, with no distinct relation in appearance, behaviour, location or movement to the resident whales, were also encountered. Based on these

differences, these new whales were named ―transients‖. Additionally, in

1991, a landmark field study led by Dr. John Ford, from the Vancouver Aquarium, identified large groups of killer whales off the Queen Charlotte

Islands that did not match identification photos of any transients or residents known in the Pacific Northwest. These whales became known as ―offshores‖.

Feeding:

Resident, transient and offshore killer whales feed differently. Resident killer

whales are strictly fish-feeders, and specialize on salmon, particularly

chinook. Transients feed on other marine mammals such as seals, porpoise, and grey whale calves. In fact, the common name ―killer whale‖ comes from

the fact that transients are the only cetacean species that eats other whales. Offshore killer whales feed primarily on large sharks.

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Killer whales feed cooperatively within their family groups, whether herding

fish or chasing marine mammal prey, and all prey is shared with the calves and juveniles. One whale may hold the prey beneath the surface while

others attack and feed on the carcass. When larger whales are attacked, often just the tongue is eaten before the heavy carcass sinks. The killer

whale‘s conical teeth are designed for holding and tearing prey; they mesh when the jaws close.

Communication:

Killer whales use an impressive array of acoustic sounds, including squeaks,

squawks, squeals, screams, trills and whistles. Despite this diversity, each

killer whale sound is really one of two basic types. Pulsed calls are bursts of sound consisting of rapidly generated pulses, while whistles are constant

sounds of varying pitch and duration. While some sounds are used by all killer whales, each killer whale pod has

its own distinct repertoire of sounds which forms a specific ―dialect‖ and animals within the pod develop what seems to be ―accents‖ peculiar to their

specific pod. Pods that meet infrequently have very different accents and dialects.

Using these sounds, killer whales can communicate across considerable

distances and keep track of each other this way. We can only guess at what information they‘re exchanging, since specific behaviours have yet to be

associated with particular sound patterns. A specialized use of sound among toothed whales is bio-sonar, or

echolocation. Making clicking types of sounds, the whale sends pulses into

the water and analyzes them as they reflect back from distant objects. The clicks can be adjusted for pitch, duration and number of repetitions

(frequency) per second. One or two clicks per second are produced in locating a distant object, but as the object draws closer, as many as 200 to

300 clicks per second may be generated. These ―click trains‖ are so fast that the sound is more of a buzz than a distinct clicking. As in communication,

the sound is concentrated and directed through the melon at the front of the head, and reflected sound is received through the lower jawbones.

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Staying Alive: Survival Adaptations

Staying alive is hard to do, and only the best adapted animals and plants succeed. To survive, all animals must obtain food and oxygen while

protecting themselves from predators. The shapes, colours and behaviours of animals give clues about how they survive in their habitats.

The structures and behaviours of animals are adapted to help them survive

in their habitats. Many types of adaptations improve animals‘ ability to survive: the change over time of a whale‘s terrestrial forelimb into a flipper

for swimming is a structural adaptation; the development of the stonefishes‘ venom is a physiological adaptation; and the careful

grooming of a sea otter to clean its fur to keep it waterproof is a behavioural adaptation.

Here are some representative Aquarium animals, categorized by their ecosystem and details of how they stay alive:

ECOSYSTEM: TROPICAL WATERS

Seahorses (camouflage)

Seahorses have heads like horses, tails like monkeys, pouches like kangaroos and armoured plates like

armadillos. No wonder they do not resemble any other fishes!

Seahorses spend most of their lives clinging by their

coiled tails to coral, waiting for shrimps and other food to

cruise past them. When they spot a tiny crustacean or worm, they suck it into their long, toothless jaws.

Seahorses are not fast swimmers, so they protect themselves by changing colours to match their

surroundings. If a predator does detect them, they have another form of defense—seahorses are covered in

armoured plates! These unusual fishes have even more surprises in their pouches. Females lay eggs in the

pouches on the front of the males‘ bodies—and the males give birth to baby fish after two to seven weeks!

Puffer-fish (shape shifter and poisonous)

Puffer-fishes can inflate their bodies like balloons, making themselves far too round and large for most predators to swallow. Even large-mouthed

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predators may find that the spines protruding from these puffed up fishes

make them an unpalatable meal. To feed themselves, puffer fishes use their plate-like teeth to crunch through snails, shellfishes, crabs and corals. Some

puffer-fishes can live in fresh water.

Black Tip Reef Sharks (adaptations as predators)

There are close to 375 different species of sharks. Sharks are boneless fishes that have skeletons made of cartilage (KAR-tih-lage), the same type of

material that is in the tip of your nose. Unlike other fishes, most sharks cannot pump enough oxygen carrying water over their gills to breathe and

must increase the flow of water over them by resting in water with a current

or by swimming.

The grey backs and light-coloured undersides of sharks make them hard to see in the open ocean. This helps to make them efficient predators as it is

difficult for their prey to see them coming from any angle. But not all sharks are flesh eating. Some sharks feed on bottom-dwelling animals, such as

snails, crabs and shrimps.

The skins of sharks are covered with tiny, sharp scales, called dermal denticles that point mostly toward their tails. If you ever were to rub a shark

from tail to nose, it would feel like sandpaper enveloped in a slimy mucous layer. This mucus protects all fishes from parasites and infection. Three to

15 sets of specialized, enlarged dermal denticles are loosely embedded in shark jaws—these are their teeth. Sharks lose these teeth easily, but new

ones continually grow on a conveyor belt-like reserve system. The fearsome

jaws of many sharks are large and flexible which allows them to thrust their jaws out to capture prey.

ECOSYSTEM: AMAZON RAINFOREST

Sloth (camouflage)

The sloth is a mammal that spends most of its life eating leaves while hanging upside down in the

rainforest canopy. Once a week, a sloth will descend to the forest floor to defecate. If they

were to defecate while suspended high in the trees, their excrement would leave a visible calling

card for their predators such as the Harpee eagle. This would be a serious threat to a sloth, as they

are normally among the slowest-moving animals

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on land, although they are also capable of great speed.

The sloths slow movements and green-tinted shaggy coats help it to blend

with its surroundings and avoid notice. Algae, giving the animals a greenish hue colonize the hollow shafts of hairs in a sloth‘s fur. Their coats are also

homes to small moths.

Sloths are good swimmers and this activity may rid them of these moths.

Their fur is parted ―backwards‖ along the centre of their chests and stomachs so that rainwater will flow off them as they hang upside down.

Caimans (camouflage)

AquaFacts: Crocodilians Caimans are relatives of alligators and crocodiles. They

lie still in the water like logs, with only their eyes and nostrils protruding above the surface, prepared to lunge

at any unwary birds, fishes, or mammals that stray too close to their tooth-lined jaws. Their almost invisible

surveillance of potential prey also makes it difficult for their predators, including the anaconda, to see them. All of the toes on their short legs are

partly webbed, allowing them to maneuver easily on land and in water.

Anacondas (camouflage)

AquaFacts: Anacondas

Anacondas live on the ground near rivers or ponds and grow to more than eight meters in length and can weigh up to 230 kilograms. They lie

camouflaged on the forest floor, waiting for their prey. With one lightning-bolt strike, they have their prey securely in the grasp of their inward-

pointing teeth. They then coil themselves around their prey, constricting more tightly each time it exhales. Over a period of a couple of minutes the

prey suffocates. Anacondas can devour prey from the size of a small rodent to a caiman nearly two meters long, although the latter may take more than

a week to digest.

Electric Eels (electricity for protection)

Electric eels superficially resemble slimy snakes more than they do other

fishes. The electric eel is an obligate air-breather - denied access to the surface it will drown. They take up oxygen by way of an extensively

diverticulated and richly vascularized mucosa which is distributed on the floor, and roof, of the mouth. They excrete most of their CO2 via the skin.

Very little is excreted via the gills.

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Electric eels use modified muscles arranged like tiny batteries to generate

low voltages of electricity. They use this electricity to navigate, for protection and to stun their prey. They mostly hunt small fishes using 500-

volt shocks to stun them.

Vine Snakes (camouflage)

The vibrant, green vine snakes pass a great part of their lives draped from

the branches in the canopy of trees, hanging motionless. Their slender bodies blend well amongst the greens of the forest, where they hunt birds.

Vine snakes use vision as well as special touch and chemical sensors to monitor their surroundings. Poisonous fangs supplement these capabilities

for hunting. Like other snakes, vine snakes do not have eyelids, eardrums or legs.

Poison Dart Frogs (warning colouration)

AquaFacts: Frogs These tiny, jewel-like frogs boldly advertise their highly poisonous nature to

potential predators. The skins of poison arrow frogs display classic warning colours—red, yellow and orange. These small frogs have added shocking

greens and iridescent blues to their colour palette to complete their gaudy and dazzling arrays of stripes, dots and swatches. True to their warning

colours, poison dart frogs secrete a venomous mucus through their skins to keep them moist. Native peoples of the Amazon rainforest extract the poison

from these frogs and apply it to the tips of arrows used in bows or blow pipes. One species‘ toxin is so virulent that the tips of the arrows only need

to be brushed against the frogs‘ backs.

Frogs and other amphibians must live near water, even though they never

swallow it. They drink through their skins. They are capable of breathing through their skins, but for the most part, use their lungs.

They eat insects that also live on the rainforest floor.

EOSYSTEM: PACIFIC NORTHWEST COAST

Sea Anemones (camouflage)

Sea anemones are simple, well-armed animals. Their many, petal-like tentacles are laced with stinging cells that

immobilize prey, such as small shrimps and crabs. Once anemones have successfully captured their dinner, they

use their tentacles to manoeuvre it into their centrally located mouths.

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Anemones spit out the indigestible parts of their meals, including pieces of

shell.

At low tide, sea anemones that are attached to rocks or burrowed into sandy beaches prevent themselves from drying out by tucking their tentacles into

the middle of their cylindrical bases. This action traps water inside their central cavities. Sea anemones often stick pieces of shells or tiny rocks to

their columns to camouflage themselves. Many exposed anemones look more like drab stewed tomatoes with beach flotsam decorations than the

exquisite aquatic flowers they resemble when seen ―open‖ underwater.

Even when their tentacles are ―out‖ in tide pools, or underwater, the stinging cells of sea anemones are harmless to most humans. Take care to gently

use your pinky finger if you wish to touch one of these soft creatures.

Sea Snails (cryptic colouration)

Sea snails make the shells that they carry on their backs and use them as

mobile homes. They use their single, large foot to move slowly and for holding onto the ocean bottom. Most snails can pull their foot into their

shells and firmly seal the ―door‖ shut with the operculum (oh-PER-kew-lum), a tough, oval-shaped piece of material. Many snails scrape and eat algae

from rocks with their sandpaper-like tongues, often leaving a maze of clear snail-trails behind them. Some sea snails use their rasping radulas to bore

holes in other creatures‘ shells to feast on the animals inside.

Chitons (camouflage)

The flattened bodies of chitons (KYE-tons) are covered by eight partially

overlapping shell plates. Chitons‘ strong feet and low profiles allow them to cling to rocks in turbulent surf and strong currents. Some chitons have

eyespots that sense light. Many chitons feed at night, using their toothed tongues to scrape algae off rocks.

Octopus (camouflage, shape and colour shifter)

All octopuses use their well-developed eyes to scan for prey and predators. They use their eight sucker-lined arms to grasp potential dinner items, such

as crabs, snails, oysters, abalone, clams, mussels and small fishes. They transfer their prey to their mouth, located on their undersides, in the middle

of their many arms.

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When octopuses see predators, they flee as quickly as possible, often hidden

by murky clouds of ink that they squirt behind them into the water to confuse any pursuers.

Octopuses use other talents to avoid predators and hunt prey—they shape-

shift and colour-change. They can squeeze their soft bodies through very, very small openings under rocks and at the entrances of caves, where they

often live. Octopuses are also masters of skin-colour changes, either blending with their surroundings or pulsating red when alarmed. These

disguise artists can even alter the texture of their skin to match their backgrounds.

Crabs (protection)

Most crabs have hard shells that cover their bodies, antennae, powerful claws, and two-to-four pairs of

walking legs. Crabs use their specialized pincers and appendages as knives, forks and spoons to eat

everything from marine worms to seaweeds. Most crabs use eight legs to move quickly—sideways.

When the crabs‘ hard shells become too small and tight for them, they

develop a soft, new covering underneath the old shells. The smaller, older shells split along the back and the crabs reverse out of them. They are very

vulnerable to predators during this process and usually hide while their newly exposed shells are hardening. This process is called moulting. Crabs

moult many times before they are fully grown animals, scrubbing

themselves with tiny grooming brushes.

Sea Stars (protection)

Most sea stars have five arms, but some species, such as the sunflower star, can have up to 26! If sea stars lose any of their arms, they can usually grow

a new one. These animals use hundreds of suction-tipped tube feet located on the undersides of each arm to move slowly along the bottom of the

ocean.

Most sea stars eat by using their tube feet to pry apart the shells of their mussel, clam or snail dinners. Once they have ―opened‖ their prey, they

push their stomachs out of their bodies through their mouths. Sea stars digest the soft meat of their prey outside their bodies. They use eyespots

located at the tip of each arm to detect how light or dark their surroundings are.

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Sea Urchins (protection)

Sea urchins are bristling balls of spines. Like porcupines, sea urchins use spines as protection. They use five double

rows of tube feet to anchor themselves to the sea bottom, to move slowly, to seize bits of food, and to keep their

spines free of debris. They also use five interconnecting teeth on their undersides to graze kelp and other

seaweeds. This feeding apparatus is called Aristotle‘s lantern.

Sea Cucumbers (protection)

Most sea cucumbers are the shape of—yes cucumbers—and some are the

consistency of jello. Although some sea cucumbers do have soft spines and hundreds of tube feet, sea cucumbers do not outwardly resemble their close

relatives, the sea stars and the sand dollars. The internal organs of sea cucumbers are arranged into five equal parts, in a similar fashion to their

relatives. Some sea cucumbers mop up food from the water or the ocean bottom using the sticky feeding trees, or tentacles, around their mouths.

Others are filter feeders that sift tiny plants and animals out of the water.

Herring (schooling behaviour)

Herring hunt for prey and baffle predators as they dart about in huge schools. These small, silvery fish group together in search of waters thick

with plankton. Herring gain protection from predators through their immense numbers. When a predator approaches a school, it may be overwhelmed by

the flashing silver sides of thousands of herring, and be unable to pick out one individual prey. A dense school of herring moving in unison may also

discourage a predator by appearing as a single, much bigger creature.

Sea Otters (tool use and grooming behaviour) Sea otters live in the cold waters of the North Pacific Ocean, ranging from

Japan to California. Unlike other marine mammals, sea otters do not have a thick layer of blubber to keep them warm. Instead, they consume great

quantities of food—up to one quarter of their body weights each day, or approximately 11 kilograms. Sea otters recline on their backs at the water‘s

surface often enveloped in blades of the kelp forest, frequently employing tools to hammer and pry open abalones, sea urchins, crabs and clams.

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Sea otters also use their baggy fur coats to keep warm. They grow the

densest fur of any animal on earth. Their constant grooming ensures that a layer of insulating air becomes trapped in their coats and that their fur

remains clean enough to insulate them from the chilly waters they live in.

Harbour Seals (blubber and fur for warmth)

These rounded, doe-eyed seals are called Harbour seals because they live in shallow ―harbour‖ waters near

beaches, sandbars, rocks or other flat land areas. They prefer these flat places because they cannot move

easily on land. Seals come on shore to rest and to give birth. In the water, Harbour seals dart about gracefully

using their hind flippers for power and their front ones to steer. They eat fishes, shrimps, and other invertebrates.

Steller Sea Lions (blubber for warmth)

Steller sea lions are huge, eared seals. Males grow to be the size of two

record-sized grizzly bears! They have very powerful front flippers that they use for propulsion. Steller sea lions hunt fishes, squids, octopuses, and some

eat seals. They are much more comfortable on land than harbour seals, and come ashore to rest, lounge in the sun, and to breed.

Pacific White-sided Dolphins (camoulfalge) Pacific white-sided dolphins travel in schools of between 2 and over 1000

individuals. They are the most active and playful cetacean in northeast Pacific waters. They are among the fastest dolphin species and can reach up

to 40 kilometers per hour. They hunt for squid, herring, sardines, anchovies,

salmon, cod and hake and swallow their food whole. They use echolocation to find their way around and to catch their food. Killer whale and sharks are

predators of dolphins.

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ECOSYSTEM: ARCTIC OCEAN

Beluga Whales (camouflage)

Belugas are grey when they are young and become paler as they grow older.

Their mature white bodies blend well with the snow and floating ice in the Arctic, where most Belugas live. This is excellent camouflage! Belugas do not

have dorsal fins, but do have hard dorsal ridges which they use to crack open ice up to 7.5 cm thick. As much as 40 percent of their body weight is

blubber, so they can keep warm in icy waters. All this blubber, however, does not make them fast swimmers. They are fast enough to catch some

schooling fishes to eat, but also feed on slower animals that live on the bottom of the ocean. They have jointed necks that enable them to pick up

the mud that they sift through for food.

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