GEL 16 Lecture Notes - Lecture 13: Viviparity, Solution, Osmoregulation
Document Summary
Gel16 - lecture 13 - marine fish, reptiles, and birds. Of 24,000 known species, about 15,000 are marine. Oldest of vertebrates according to fossil records. Largest group of vertebrates in terms of species and abundance. Around of vertebrate species are fish. Anatomy includes: dorsal fin, pectoral fin, pelvic fin, anal fin, and caudal (tail) fin. Muscular, circular mouth with rows of teeth in rings. Lack paired fins and scales like other fish. More species than all other vertebrates combined (23,000) Hinged jaws (allows for variety of feeding methods) Countershading (white on bottom, blue on top) helps with camouflage. Chondrichthyes and osteichthyes considered to be more advanced. General characteristics in these groups: efficient gills, scales, paired fins, lateral line and other sensory organs, streamlined body. Ovovivipary - internalized egg hatches while still in the female before the young are birthed. Construction of gill is the same in all fish.
