TODAY’S FISHES Section 33.2. JAWLESS FISH - AGNATHANS Lampreys and hagfish Scaleless Eel-like...

TODAY’S FISHESSection 33.2

JAWLESS FISH - AGNATHANS

• Lampreys and hagfish• Scaleless• Eel-like bodies• Multiple gill slits• Unpaired fins• Skeletons of cartilage• Hagfish – ‘vultures of the sea’ scavengers• Lamprey – parasites on other living fish

HAGFISH

LAMPREYS

CARTILAGINOUS FISHES

• Sharks, skates and rays• Skeletons made of cartilage

strengthened with calcium carbonate – lightweight and strong• Streamlined body• Placoid scales – give skin a rough

texture• Teeth are modified scales and are

replaced as needed throughout lifetime

SHARK

SKATEROUNDISH OR TRIANGULAR SHAPE

RAYKITE-SHAPED WITH 1 OR MORE VENOMOUS BARBS IN THE TAIL

BONY FISHES

• Largest group of fish• Endoskeleton made of bone• Lateral line system – acts as a sensory organ to

detect movement in the water (theirs and other objects)

• Operculum – hard gill cover which allows fish to move water over the gill while remaining still in the water

• helps fish conserve energy• Swim bladder – allows fish to maintain water

depth • gas in fish rises; gas out fish sinks• Two groups: ray-finned fish & lobe-finned fish

RAY-FINNED FISH

•Most fish are in this group•Teleosts – the most advanced •Highly mobile fins•Very thin scales•Completely symmetrical tails•95% of all fish species

YELLOW PERCH – A RAY-FINNED FISH

LOBE-FINNED FISH

•Only 7 species – 1 coelacanth + 6 lung fish• Each fin has a long, fleshy, muscular lobe supported by a central core of bones•May be a direct ancestor of amphibians, but probably not

COELACANTH

LUNG FISH