Chapter 23 Chordates

50,000 living vertebartes, for each living species–>ten extinct

Nerve cord, Notochord, Pharyngeal slits, postanal tail

Urochordata,Cephalochordata= nonvertebrates, Craniata (includes vertebrates)

Also called Tunicates, marine animals, many secrete tunic (cellulose sac surrounds animal), young have notochord and nerve cord

Lancelets, scaleless chordata, notochord throughout life, closest relatives to vertabrates

animals with a cranium

Jawless fish, not monophyletic, Hagfish/lamprays

Ridgid (bony) spinal column, vertebral column-encloses and protects dorsal nerve cord, head, Neural crest, closed circulatory system, Endoskeleton

liver, kidney, endocrine glands, heart

group of embryonic cells that forms many vertebrate structures

Jawed vertebrates, cartilagenous and bony fish, fish=single-loop blood circulation

cartilagenous fishes(sharks), Ampullae of Lorenzini-electroreceptive organ, placoid scales, rows of teeth, conspicuous gill slits, variety of feeding habits

Bony fish, 2 major groups- Lobe-finned fish(scaropterygii)& Ray-finned fish (Actinopterygii)

includes lungfish and coelacanths, where tetrapods diverged,

Includes all other bony fish, largest group-teleostei, premaxilla mobile(allows for protrusion or moving of jaw), HOMOcercal tail

terestrial vertabrates,( No ansectrial fish forms alive today-closest relatives are lungfish), Four limbs, five digits on each limb, Stapes & tympanum, first vertabra modified into atlas (nodding & rotation of head)