fishes (yes, that’s the proper word) ichthyology (the study of fish)

FISHES (yes, that’s the proper word)

ICHTHYOLOGY (the study of fish)

• MARINE VERTEBRATES; FISHES CHAP 6.

• Read pgs. 177-187

• covering the topics of – phylogeny, evolution and anatomy

History of Ichthyology (don’t write this, just read)

• Aristotle made first written recordings and observations about fish (300s B.C.)

• For 2,000 years no work done on fish• Then in 1500s, three scientists published new

works on fish• Led to rapid expansion in knowledge and new

interest in study of fish• Linneaus and modern classification of fish• 20th century sees diversification of ichthyology

Fishes Are Diverse (don’t write this, just read)

• Live in diverse habitats

• Have different body shapes

• Have different body structures

• Have different reproductive strategies

• Have different feeding styles

• Inhabit multiple niches in life cycle

Fishes are very diverse

I’m not kidding, they are really diverse

I. GENERAL INFORMATION• cold-blooded, vertebrate

that breathe w/gills and move w/fins

• most numerous vertebrates more than 30,000 species

• 400-500 in the reef area• smallest

– Philippine Island Goby – 1/3”- 1/2”

• largest – Whale Shark – 50’ and

several tons

Diversity of Body PlanDiversity of Body Plan

Diversity of Body PlanDiversity of Body Plan

Rover-predatorTuna, swordfish, bass, trout

Lie-in-waitPikes, barracuda, gars

Surface-orientedFour eyed fish, killifish

Bottom roverCatfishes, sturgeons

Bottom clingerSculpins, gobies, clingfishes

Flatfish

RattailChimeras, brotulas

Eel-likeDeep-bodiedPerch,

Common Body Plan DescriptorsCommon Body Plan DescriptorsElongate, fusiform, or basslike

Anguiliform, eellike, or attenuated

Ovate or truncated

Compressed, compressiform, thin, narrow, deep, or perchlike

Depressed, depressiform, or flattened

Globiform, subcircular, or hemispherical

II. ANATOMY

Front Side

• FUSIFORM

• COMPRESSED

• DEPRESSED

• ATTENUATED

A. Body shape

II. ANATOMY

Front Side

• FUSIFORM

• COMPRESSED

• DEPRESSED

• ATTENUATED

A. Body shape

B. Mouth Position is significant

• ambush

• predator

• bottom feeder

B. Mouth Position is significant

• ambush

• predator

• bottom feeder

C. Feeding Patterns (pg. 187-191)

• Predators• Nibblers- crushing teeth, may eat coral polyps and

stone• Strainers- plankton feeders• Suckers- disc w/lips, barbels (whiskers) for

searching the sand• Parasitic- (external or internal) rasping teeth to

penetrate scales ex. hagfish and lamprey ex. canduri or vampire fish -suck blood from

gills• read passage from text

D. Know fin names and functions from handout

FISH ANATOMY

• FINS – movable structures that aid the fish in swimming and maintaining balance

• May be sharp, spiny or soft • Most have: Dorsal fin

Anal fin Caudal fin (tail)

Pectoral fin Pelvic fin Adipose fin (only some)

Fish live(background information)

• 13% associated with open ocean

• 1% in surface (epipelagic) layer

• 5% in unlighted sections of water column (deepwater pelagic fishes)

• 7% on bottom (deepwater benthic fishes)

• 78% of marine fishes (44% of all fishes) live in narrow band along continents in water less than 200m (continental shelf)

Fish DiversityFish Diversity

• By volume 97% of all water is marine

• 58% of fish species are marine, 41% are fresh water– Mainly due to speciation in response to

isolation (ponds, lakes, rivers)

– Close to 80% of all marine species live in water along coastlines less than 200 m deep

III. EVOLUTION

• Draw diagram from

Marine Biology Text pg. 179

• Phylogenetic Tree

–(shows evolutionary relationships)

• Emphasis on Fish Classes

EVOLUTION(background information)

• Earliest fish – Ostracoderms• fossils date to the Ordovician

Period – 425-450 Million years ago

• slow, bottom-dwelling w/thick bony plates and scales, poorly developed fins and no jaws

• believed to be first animal w/a backbone

• became extinct 250 million years ago

IV TAXONOMY• Kingdom Animalia• Phylum Chordata

– dorsal nerve chord• Subphylum Vertebrata

– dorsal backbone made of cartilage or bone

• Classes– Agnatha– Chondrichthyes– Osteichthyes

Class Agnatha “jawless”

• Do not have a lateral line system• Cyclostomes “round mouths” ; have neither plates nor scales• Notochord, eel-like shape, a cartilaginous skeleton, and

unpaired fins

Lampreys: - free living or parasitic; adapted for sucking blood and body

fluids of other fish - Feeding: attach by suction, tear a hole with toothy tongue, secrete chemical to prevent clotting

- do not have a stomach: mouth, esophagus, a straight intestine, and associated glands

Problem for great lakes sport and commercial fishermen

Hagfish(for background information)

• Bottom dwellers in cold marine waters

• Scavengers of dead and dying fish on ocean bottom

• Feed by sawing the fish with its toothed tongue from the inside out

• Extremely flexible to avoid capture or to clean the slime off after self-defense secretions

• When not feeding they remain hidden in burrows on the ocean floor

Class Chondrichthyes(cartilage fish)

• Sharks, skates, and rays • They have skeletons of cartilage, not bone• Also have movable jaws and skeletons with paired fins• No swim bladder

Sharks• Sharks are scavengers that eat injured fish, carrion, garbage and other

waste from ships as well as animals such as seals, turtles, birds, whales, crabs, and a wide range of fishes.

• The shark’s mouth has 6 to 20 rows of backward-pointing teeth. They can detect blood from an injured animal as far as 500 miles away.

• They swim with a side-to-side motion of their asymmetric tail fins. Behind their heads are pectoral fins that jut out of their bodies like the wings of a plane.

• Gas exchange requires a continuous passage of water over a shark’s gills.

Rays and Skates

• Skates are a family of flat-bodied rays found in warm and temperate seas. They have eyes located on the upper surface of the body while the mouth and gills are located on the lower surface.

• Their color makes them almost invisible because when another animal looks down on them, they are camouflaged with the darkness of the sea bottom. When looked up from underneath, the animal is camouflaged with the light from the sun.

• Water enter their gill through two openings called spiracles atop their heads. Most feed on mollusks and crustaceans.

Meyr’s video

Osteichthyes (bony fish)• Osteichthyes make up most of the vertebrate

population in fresh water and in salt water. • Ray-finned fishes have fins that are supported by

the long bones called rays. They are the most familiar fishes and include snakelike eels, yellow perch, cave fish, herring, and lantern fish.

• Lungfishes have gills where gas exchange takes place between water and the blood. They burrow unto the mud and cover themselves in mucus to stay moist until the pond refills.

• Lobe-finned fishes, or coelacanths, have paddle like fins with fleshy bases.

• Lobe-finned fishes, or coelacanths, have paddle like fins with fleshy bases.

V. PHYSIOLOGY (fishyology)

• Diffusion- moves O2 from water into the blood (hemoglobin)

• the LARGE SURFACE AREA of the gills facilitates diffusion the gills are HIGHLY VACULARIZED

• ***Lung fish- modified SWIM BLADDER vascularized. Gaseous O2 can diffuse into the blood stream. Some fish can gulp air.*****

• chromatophores (pigment cells)

FISH ANATOMY

• GILLS – organs on the side of fish that allow them to breath

• Water is drawn in through the mouth and out the gills

• Dissolved oxygen in the water is taken into the blood and carbon dioxide is released

Draw and label the gill, gill arch, gill rakers

FISH ANATOMY - EYES• similar to other

vertebrates, but differ in a couple of ways: – spherical lens– no eyelids– size of the eye

depends on the amount of light reaching the eye

• Shallow water – small eyes

• Deep water – large eyes

• Dark caves – blind

FISH ANATOMY- ears, taste, smell, sensitive cells

• Have inner ears• Have taste buds in their mouths,

on their lips and on their body/fins• Have highly developed sense of

smell

• Fish react to changes in water pressure, temperature, currants and sounds w/pressure sensitive cells along a lateral line near the base of the tail

Do fish drink water?

• Yes and No

• It depends on the type of water it lives in.

• VI. REPRODUCTION synonym spawning

• Sperm milt

• Eggs roe

• Reproduction is determined by

• 1. Age and 2. Season

• Types?

• Egg laying - most bony fish

• Live bearing- internal fertilization and internal development. Not very common, pioneered by Chondrichthyes

Reproductive strategies• Hermaphrodites-• Sex reversal- is it better to be female or male?

• Unique methods to protect laid eggs• Camouflage• Mouth incubation• Guard the nest

• EXTERNAL INTERNAL DEVELOPMENT DEVELOPMENT

• EXTERNAL INTERNAL DEVELOPMENT DEVELOPMENT

• Many eggs few eggs few eggs

• EXTERNAL INTERNAL DEVELOPMENT DEVELOPMENT

• Many eggs few eggs few eggs

• No care guard incubate

• EXTERNAL INTERNAL DEVELOPMENTDEVELOPMENT

• Many eggs few eggs few eggs• No care protection incubation

•Few survive higher % survive highest % survive

• EXTERNAL INTERNAL DEVELOPMENTDEVELOPMENT

• Many eggs few eggs few eggs• No care protection incubation

•Few survive higher % survive highest % survive

• 10/1000 10/100 10/10

• ENERGY/ BENEFIT RATIO

• A limited amount of energy can be shared in different ways. % of survival is different but overall numbers remain about the same