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Phylum Chordata. Ch. 34. Characteristics. Notochord Dorsal, hollow nerve cord Muscular post-anal tail Gill slits. Gills. Simple Chordates. Urochordata – tunicates Cephalochordata – lancelets. Challenges Faced. Chasing food Grabbing food when close Getting oxygen from environment
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Phylum Chordata Ch. 34
Characteristics • Notochord • Dorsal, hollow nerve cord • Muscular post-anal tail • Gill slits
Simple Chordates • Urochordata – tunicates • Cephalochordata – lancelets
Challenges Faced • Chasing food • Grabbing food when close • Getting oxygen from environment • Getting oxygen through body • Preventing dehydration • Maintaining body temperature • Keeping embryos from drying out
Fish • Agnathans • Evolution of jaws • Lateral line • Swim bladder • operculum
Fish • Evolution of jaws
Fish - Chondrichthyes • Lateral line
Fish - Osteichthyes • Operculum • Swim bladder
Class Amphibia • Gills as juvenile • Lousy lungs • Moist skin
Class Amphibia • Improved circulation
Class Reptilia • Paraphyletic
Class Reptilia • Dry skin • Amniotic eggs • Internal fertilization
Class Reptilia • Branching in lungs • Partial septum in heart
Class Aves • Lightweight, hollow bones • Large breastbone • Feathers / endotherms
Class Aves • Four-chambered heart
Class Aves • Best lungs – one-way respiration
Class Mammalia • Monotremes • Marsupial • Eutherians
Class Mammalia • Mammary glands • Hair • Specialized teeth