Petromyzontidae (lampreys) Jawless 7 gill apertures No paired fins (pectoral, pelvic anal) Cartilaginous skeleton American brook lamprey (Lampetra appendix) Petromyzontidae Adults usually fish predator/parasites Sea lamprey adversely affected Great Lakes fishery Ammocoetes (eyeless, no buccal disk) eat organic matter in sediments Sea lamprey (Petromyzon marinus) Acipenseridae (sturgeons) Large size Subterminal mouth Shovellike Barbels Bony plates on body (few scales) Heterocercal caudal fin Acipenseridae Benthic feeders Many species threatened Overharvesting Habitat degradation Long generation time Eggs used for caviar Shovelnose sturgeon (Scaphirhynchus platorynchus) Polyodontidae (paddlefishes) Large size Long, paddlelike snout Smooth skin (no scales or plates) Heterocercal caudal fin Skeleton mostly cartilaginous Paddlefish (Polyodon spathula) Polyodontidae (paddlefishes) Planktivorous Paddle a sensory device? Numbers greatly reduced Good food quality Long generation time Lepisosteidae (gars) Cylindrical body Long jaws with teeth Body covered with ganoid scales Caudal fin modified heterocercal type Lepisosteidae (gars) Piscivorous; ambush predators Inhabit vegetated areas Eggs toxic to homeotherms Commercially unimportant Longnose gar (Lepisosteus osseus) Amiidae (bowfins) Cylindrical body; up to 0.6 m long Terminal mouth Cycloid scales Long dorsal fin Black spot at base of caudal fin Caudal fin modified heterocercal type Bowfin (Amia calva) Amiidae (bowfins) Preys on variety of aquatic animals Inhabits wetlands and backwaters of rivers Lunglike gas bladder Unpalatable flesh Bowfin cruising