Invertebrate Chordates

Invertebrate Chordates Hemichordata Urochordata Cephalochordata Hemichordates Deuterostomes  Gill slits  Dorsal nerve cord  Classes of Hemichordates  Enteropneusta – Acorn worms – Shallow marine animals  Pterobranchia – Rhabdopleura – Colonial, send out feeding zooids Acorn Worm Phylum Chordata All chordates are deuterostomes  At some time in their life, all chordates have:  – Notochord – Pharyngeal gill slits – Dorsal, hollow nerve cord – Postanal tail Subphylum Urochordata Sea squirts or tunicates  Larvae show the characteristics of chordates  Adults lose notochord, nerve cord, and tail  Only animals to have cellulose in their bodies!  Tunicates: Are filter feeders  Do not have complex nervous systems  Often form large colonies  Are monoecious  Tunicate Larva Adult tunicates Subphylum Cephalochordata Lancelets (Amphioxus)  Notochord runs from head through tail  Muscles can contract the notochord  Live partially buried in marine sediment  Filter feeders  Dioecious 