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?

http://www.animalpicturesarchive.com/animal/APAsrch3.cgi?qt=mudskipper

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