Jawless Fish Phylum: Chordata Sub-Phylum: Vertebrata Class: Agnatha

Fish The Water Dwellers Most fish are cold blooded vertebrates that live in water. Scientists believe that fish were the only vertebrates on Earth for about 150 million years. Scientists classify fish living today into three classes.

Subphylum Vertebrata Fishes

Jawless Fishes Do not have a lateral line system 45 species of lampreys (fresh water) and hagfish (oceans) Cyclostomes “round mouths” ; have neither plates nor scales Notochord, eel-like shape, a cartilaginous skeleton, and unpaired fins

Jawless fish: Hagfish

Hagfish are of the order, Myxiniform. They are related to the slimefish. They have the peculiar habit of tying themselves into knots in order to shed their slime coat and make a new one. 20 known species Deep, cold waters 2.6 ft. Skin is used for leather goods Hagfishes

Hagfish feed on polychaete worms, shrimp, and dead or dying fish attach to fish, form a knot in the tail and pass it forward to rip off flesh. Image © BIODIDAC.Image usually enter coelomic cavity and feed on soft parts many mucous glands present for anti-predator defense Bottom dwellers in cold marine waters 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

Jawless fish: Lamprey

Lampreys Lampreys are of the order, Petromyzontiform. They are suckers and attach themselves to fish in order to parasitize off them. Found in Freshwater 30 species

- free living or parasitic; adapted for sucking blood and body fluids of other fish - highly developed sense of smell: nasal pore leads to olfactory sacs that connect with olfactory lobes - 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

Sea Lamprey Life Cycle Life cycle of sea lamprey –Adult parasitic, feeding stage –Adults swim into small freshwater streams to breed –Larvae live in sediment as filter feeders up to seven years –Metamorphosis, migration to lake or sea to become parasitic adults

Lamprey Anatomy

FINS LIVING JAWLESS, e.g. LAMPREY: ONLY ALONG BODY

D-eel-icious, if you appreciate an earthiness So what does lamprey taste like? "I would have to say it tastes like lamprey," says Chef Bob Bennett, "because it does not have a flavor that you can associate with anything else."

Hagfish Lamprey Jawless Fishes – modern diversity

Larvae of a jawless fish Skeletal elements of a jawless fish

lampreys Jawless Fishes – modern diversity

Jawless Fishes – ancient diversity

EXTINCT JAWLESS FISH Paired Fin

EVOLUTION Earliest fish – Ostracoderms fossils date to the Ordovician Period – 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

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