Phylum ChordataCh. 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• 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
What type of circulatory system?
Class Amphibia
Class Amphibia
• Gills as juvenile• Lousy lungs• Moist skin
Class Amphibia
• Improved circulation
Class Reptilia
Class Reptilia
• Paraphyletic
Class Reptilia
• Dry skin• Amniotic eggs• Internal fertilization
Class Reptilia• Branching in lungs• Partial septum in heart
Class Aves
Class Aves
• Lightweight, hollow bones• Large breastbone• Feathers / endotherms
Class Aves
• Four-chambered heart
Class Aves
• Best lungs – one-way respiration
Class Mammalia
Class Mammalia
• Monotremes• Marsupial• Eutherians
Class Mammalia
• Mammary glands• Hair• Specialized teeth
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