Chordates
What is a Chordate? Hollow nerve cord Notochord: long supporting rod below nerve cord Pharyngeal pouches: gills Tail
Muscle segments Tail Anus Pharyngeal pouches Mouth Hollow nerve cord Notochord
Nonvertebrate Chordates Tunicates Filter-feeders No notochord or tail Lancelets Exchange gas through their skin Closed circulatory system: no true heart
Fishes Aquatic vertebrates Fins: movement Scales: protection Gills: gas exchange Evolution of jaws and fins were important developments in fish
Form and Function Feeding: every mode Circulation: 2 chamber heart Excretion: release ammonia Chemoreceptors: taste and smell Lateral line system: detect gentle currents and vibrations Swim bladder: buoyancy
Jawless Fish No true teeth or jaws Skeletons: fibers and cartilage Keep notochords as adults Lampreys: parasites on fish, whales, & dolphins Hagfishes Light detecting sensors Feed on dead & dying fish Secrete slime Have six hearts
Cartilaginous Fish Sharks, rays, skates Skeleton: cartilage Toothlike scales 1,000’s teeth
Bony Fish Skeletons: bone Ray-finned fish Fins: bony spines connected a thin layer of skin Lobe-finned fish Fleshy fins support bones Some bones are jointed