Zoology - Fish

Three major fish groups

1) Jawless fish

2) Cartilaginous Fish

3) Bony fish

Two types of Jawless Fish that exist today

1) Hagfish (class Myxini)

2) Lampreys (class Cephalospidomorphi)

Hagfish (Class Myxini)

-found in ocean only

-have flexible bodies (can tie them self into a knot to escape from predators/gain leverage)

-produce slime

-known for scavenging on dead or dying fish, mainly feeding on soft tissues.

Lampreys (Class Petromyzontida)

-found in both freshwater/ocean

-spend adult life feeding on fish but return to freshwater to spawn.

-invaded the Great Lakes

-hurt trout populations

-parasitic, attaching to fish with a sucker-like mouth.

Cartilaginous fish groups

1) Sharks

2) Skates

3) Rays

4) Chimaeras

5) Guitarfish

Key features of Cartilaginous fish

- skeletons composed entirely of cartilage

- Possess jaws, fins, placoid scales

Placoid Scales

Shark scales ... resemble teeth

The largest living fish

Whale Shark

Caudal Fin

tail fin

Heterocercal Tail

Type of tail where upper lobe is larger than lower lobe.

Claspers

The modified pelvic fin of male sharks that transfer sperm to females.

Lateral Line System

System of canals running through the length of a fishes body that detect movement in the water.

Ampullae of Lorenzini

jelly filled pits on the nostril end of a shark that senses electrical currents in the water

Oviparity

Eggs are laid outside the body and embryos develop in a protective case.

Ovoviviparity

Eggs hatch within the mother's uterus.

Viviparity

Young directly attach to the mother's uterus or the embryo absorbs the mother's uterine milk.

Skates/Rays

-flattened bodies

-enlarged pectoral fins

-reduced caudal fins

Chimaeras

-large pointed head

-long slender tales

-bottom dwellers

-water is taken through nostrils

-oviparous

-use flat plates, instead of teeth, to crush prey

Bony Fishes

(class Osteichthyes)\

-constitute more than 95% of all fish

Coelacanths

ancient group of fish related to the lobe-finned fish ancestors of the amphibians

Ray-Finned Fishes

Actinopterygii

- most numerous vertebrates in the ocean

- Either have Ganoid scales or Cycloid/Ctenoid scales

Ganoid scales

Very thick/heavy scales that give fish armored appearance. Gar scales

Cycloid/Ctenoid scales

Very thin/overlapping scales that are more maneuverable. most fish have these scales

Homocercal Tails

A tale in which the upper and lower lobes are equal.

Dorsal Fin

A fin on the dorsal surface of a fish.

Pectoral Fin

The anterior pair fins of a fish.

Pelvic Fin

The posterior pair fins of a fish

Swim bladder

A gas filled air sac in some bony fishes that allows them to maintain neutral buoyancy.

Catadromous

freshwater-seawater for spawning (eel)

Anadromous

seawater-freshwater for spawning (salmon)

This fish is thought to be a connection between fish and land vertebrates.

Coelacanth

This group is the most numerous and dominant group of vertebrates in the ocean.

Ray-finned fish

mouth brooder

fish that carry their eggs in their mouth for incubation to protect and allow hatching

Ostracoderms

earliest agnathans, very abundant in their time period, jawless filter feeders, had tails and many did not have fins only a few inches long

stripes

horizontal lines across a fish

bands

diagonal lines across a fish

bars

vertical lines on a fish

ocellated spot

Spot with ring of another color

splotch

an irregularly shaped spot or discolored area

spot

circular marking on a fish

Truncate tail

tail that is "cut off", or has a straight edge

lunate tail

usually on a long distance swimmer, crescent shaped

rounded tail fin

tail fin that is fleshy, thin and circular

yaw

A side-to-side motion of a fish, pectoral fins stabilize this direction.

pitch

a fish staying up right, controlled by the pectoral and pelvic fins

roll

anal and dorsal fins help prevent this type of movement

operculum

A protective flap that covers the gills of fishes

spiracle

an external opening on a fish, used in respiration

endochondral supports

spines that run through a fin

claspers

modified pelvic fins on a male shark that allows for transfer of sperm to female

lancelet

A member of the clade Cephalochordata, small blade-shaped marine chordates that lack a backbone.

Fish Farm

fish are raised to end on someone's plate

Fish Ranch

fish are raised to end up in a creek or stream

Omega 3

The polyunsaturated fats that are good for you found in fish.