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Chapter 14

WHAT IS A MARINE

MAMMAL?

•Member of Class: MAMMALIA

•All possess major adaptations that allow them to live in the water (to a greater or lesser extent)

•Some marine mammals live entirely in the marine environment, others may come on land for part of their lives

•However, all marine mammals derive all (or most) of their food from the marine environment

POLAR BEAR

Ursus maritimus

SEA OTTER

Enhydra lutris

SIRENIANS

- Manatees and dugongs

PINNIPEDS

- Seals, sealions and walruses

CETACEANS

Whales, dolphins and porpoises

To be classified as a mammal

Must posses all five characteristics • Lungs and breath air.

• Are warm blooded and maintain a constant body temperature.

• Most bear live young. One primitive mammal group, the Monotremes (which includes the duckbill platypus and the echidna) lays eggs.

• Produce milk and nurse their young.

• Have hair at some point in their lives

14.1 Cetaceans: Whales and Dolphins and porpoises

Cetacean pronounced si-tey-shuhn

• The largest cetaceans are the whales

• the smallest cetaceans are dolphins and porpoises, which are actually small whales that range from 2-4m in length

14.1 Cetaceans: Whales and Dolphins and porpoises

– Dolphins & porpoises

SIMILARITIES?

• both very intelligent & social

• Both display a variety of acrobatic leaps, spins & somersaults out of water and into the air

DIFFERENCES?

• Dolphins have elongated snout and swim faster

2 main classes of whales: baleen and toothed

• Baleen Whales: filter feeders with baleen plates; eat zooplankton and small fish – Suborder Mysticeti

– Include species • Blue Whale – biggest animal to ever live on

earth

• Finback Whale

• Humpback Whale

• Right Whale

• Gray Whale

•The Baleen whales all

possess hundreds of

plates of baleen instead of

teeth.

•Baleen is made of keratin

and hangs from the upper

jaw.

•The fringed baleen plates

trap engulfed prey and

filter out water.

•Throat of some baleen

whales (Rorqual) is

pleated like an accordion

to expand and hold the

large amounts of water

Types of feeding methods in Baleen whales

• Rorquals take huge gulps of water to get krill and small fish

• Right whales swim slowly through near-surface waters with their mouths held open to skim and strain the small zooplankton

• Bottom feeders such as the gray whale suck up sediments on the seafloor and then filter out and eat small crustaceans and other invertebrates

2 main classes of whales: baleen and toothed

• Toothed Whales: hunters with peglike teeth; eat fish, squid, penguins, and seals

- Suborder Odontoceti

- Include species - Sperm

- Killer

- Pilot

- Beluga

- narwhal

- Dolphins and porpoises

Toothed whale feeding

• Active hunters for fish, seals, penguins, squid

• Usually swallows it whole

• Compartments in the stomach chew and digest the food

Toothed whales • Largest: sperm

whale

- 15m length

- Cone-shaped teeth on long, narrow lower jaw

• Smallest (not counting dolphins and porpoises) is the narwhal

-5m in length

-elongated front tooth grows out of the left side of its jaw

-tusk used at breeding time to attract females and to fend of rival males

Reproduction in Whales

• Fertilization & development are internal – Gestation period (period of embryonic

development) is 11 to 18 months

– Breed about once every 3 years

– Give birth to one calf

– Mother invest great deal of parental car • Close bond develops between mother and calf

• Nurses calf 6 to 10 months

• Milk rich in protein & fat (50%) helps the newborn grow fast and add on layers of insulating fat

14.1 SR

14.2 Whales Adaptation and Behaviors

• Blowhole: (nose or nostril) in whales and dolphins, opening on top of head used for breathing

- As early whales became more fully aquatic, their nostrils moved from front (snout) to the top of the head

– but must surface to breath

– Toothed whales have one nostril; Baleen whales have two nostrils

– Breath in air, carried to lungs, and exhale through blowhole

Swimming in Whales • Killer whale, or orca

– Fastest of all marine mammals 55km/hr

• Tail flukes: in cetaceans, hind flipper used to propel animal through the water – Dorsal fin used to stay on course

– Pectoral fins used for steering, braking, & balance

Other Movements in Whales • Lobtailing: behavior in which whales

wave and smash tail on ocean surface – May be a sign of aggression or announcing

its presence

• Spyhopping: behavior in which whales rise head above water to look around

• Diving: most common activity of whales. Use pectoral fins to change position from horizontal to vertical. The tail flukes are the last part out of the water

• Breaching: behavior in which wales leap out of water and crash back down – Might be a means of

dislodging skin parasites

– Form of communication

– Or just playful behavior

Whale Migration • Whales are long-

distance swimmers – Travel with extended

family group or pod

– Can cover thousands of kilometers

– Many migrated between feeding and breeding grounds • Feed and breed in cold

water (Arctic or Iceland)

• Give birth in warmer water (California or Caribbean Sea)

Keeping Warm in Cold Water

• Blubber: in cetaceans and pinnipeds, a thick layer of fat under the skin – 60cm thick

– Traps and prevents body heat from being lost

- Babies lack the fat layers of adults so it is most adaptive for them to be born in the warmer water

Communication and Echolocation in Whales

• Melon: in dolphins, a fatty bump on forehead that focuses sounds in the head

• Echolocation: in cetaceans, a natural form of sonar used in communication and hunting

Communication and Echolocation in Whales

• Stranding: a behavior in which whales become beached (and die) along shores – Internal organs crushed by their own body

weight

– Possible disease, parasites, or infection disorients leader of pod along shoreline

– Man made toxins in water from PCB, DDT

– Biotoxins from red-tide

14.2 SR

14.3 Seals and other Marine Mammals

• Carnivores: sea otters and polar bears

• Herbivores: term that describes plant-eating animals; usually have blunt teeth

Seals and Sea Lion • Pinnipeds: seals, sea lions and walruses

– Pinnipeds mean “wing-foot”

– 30 different species

– Seals and sea lions have widest distribution and inhabit all oceans • Sea lions have longer forelimbs used to move

through water and used prop itself up on land, also have external ear flaps

• Seals can only drag its body along the beach

• Both have whiskers

– Feed on fish squid mollusks, crustaceans

Reproduction in Pinnipeds

• Pinnipeds breed on land

• Females give birth and nurse on land

• Mature males right for access to females

• Dominant males acquire harems of females they mate with

• Seals and sea lions have ability to delay embryonic development so birth occurs exactly 12 months after mating – when they come ashore again to breed

The Walrus

• Walruses only found in polar seas of north Arctic

• Walruses can dive 90 meters deep to find food

• Tusks are overly developed canines found both in male and females • Used for digging up mollusks on seafloor and

hauling walrus up onto ice

Adaptations of Pinnipeds

• Not fully aquatic

• Intelligent & social

• Communicate using a variety of sounds

• Ability to dive to great depths – Deepest diver is the elephant seal 1500 m

• Layer of blubber and seals and sea lions are covered with dense fur

• Seals and sea lions have been hunted for their fur and walruses for their ivory tusks

The Sea Otter

• Sea Otter: only recently adapted to living in the ocean – 3 million yrs. Ago

• Related to weasels and minks

• Smallest of marine mammals 1 meter in length

• 3 main population life in Pacific along coast of California, Alaska & Aleutian Island & Russian islands

The Sea Otter • Found in kelp forests holding onto the

kelp to anchor themselves in choppy water

• Efficient swimmers and divers with webbed hind feet, flattened tail and streamlined body

• Eat mussel, crab, abalone, sea urchin, fish and snails – While floating on back on surface of water

they use rocks to open the shell fish

The Sea Otter • Spend most of their

life in the ocean – Eat, sleep, mate and

rear their young in the water

– May go ashore at low tide to look for mollusks

• Have no blubber but retain body heat because of very thick fur which is constantly groomed with oil from its skin

Threats to Sea Otters

• Oil spills devastate them because they can not clean their fur, otters will freeze due to insulation loss

• In 1800s otter was almost hunted to extinction for its prized fur

• Today they are protected and making a comeback

Threats to Sea Otters

• California population less then 2500 otters Russian and Alaskan population better at 20,000 and 120,000 otters

• Sea otters also at risk of predation by great white shark & orca

• Also there is a rive otter that lives in fresh water and are found in Europe, North and South America – Also need protections due to loss of

habitat, pollution, and hunting

Manatees and Dugongs

• Manatee a docile marine mammal, lives in warm shallow waters of Florida

• Live under water, feed on vegetation

• About every 15 they surface for air

• Social animal, communicate using high-pitched squeaks and whistles

Manatees and Dugongs

• Winter manatees stay in warm coastal rivers

• Summer migrate to warm ocean waters along coasts – Also found in

Caribbean, Amazon River, and along Atlantic coasts of South American and West Africa

Manatees and Dugongs

• Manatees move slowly in water propelled by gentle up-and-down movement – Have no hind limbs and forelimbs used for

feeding

– Consume up to 45 kg of vegetation a day

– Reach over 900kg body weight

– Referred to as the sea cow

Manatees and Dugongs

• Dugong is closely related to the manatee

• Classified in the order of mammals called Sirenia – named for mythical female sirens – Distant relative of the elephant

• Dugongs found in tropical Pacific and off the east coast of Africa

The Polar Bear

• Most terrestrial marine mammal

• Lives on ice floes along shore in North Pole

• Has dense fur and thick layer of blubber

• Excellent swimmer with powerful forelimbs, not fast enough in the water to catch a seal, must do that on land

The Polar Bear

• Polar bears prefer seal but also ear fish, birds, and plants

• Polar bears are solitary animals with the exception of mother bears with her cubs

• Homework page 350 1-3

14.4 The Diving Response

• Diving marine mammals can dive to great depths on a single breath because they can increase the oxygen-carrying capacity of their bodies

• Dive response is the detouring, or shunting, the blood that contains nutrients and oxygen from the rest of the body to only vital organs –brain, heart, lungs, and muscles

Other Diving Response Adaptations

• Marine mammals can inhale and exhale quickly and completely between dives – Elastic tissue in their lungs and chest

permit greater expansion

• Higher blood volume and greater concentration of oxygen-binding red blood cells than nondiving mammals

Other Diving Response Adaptations

• Diving mammals also possess oxygen-binding proteins called myoglobin located in their muscles

• Bradycardia: in diving marine mammals, ability to slow the heart rate during deep dives; important part of diving response – Ex. Elephant seal can drop heart rate from

85 to 12 beats per minute

Other Diving Response Adaptations

• Diving responses involve reflex action of nervous system – water pressure acts on pressure receptors

located in head of animal send impulses to brain

– Brain sends impulses back to heart, regulates its rate

– Impulse from brain also sent to blood vessels, causing them to constrict or dilate

• Homework page 352 1-3