Invertebrate Chordates

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Invertebrate Chordates

• Hemichordata
• Urochordata
• Cephalochordata

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Hemichordates

• Deuterostomes
• Gill slits
• Dorsal nerve cord

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Classes of Hemichordates

• Enteropneusta
• Acorn worms
• Shallow marine animals
• Pterobranchia
• Rhabdopleura
• Colonial, send out feeding zooids

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Acorn Worm
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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

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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!

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Tunicates

• Are filter feeders
• Do not have complex nervous systems
• Often form large colonies
• Are monoecious

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Tunicate Larva
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Adult tunicates
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Subphylum Cephalochordata

• Lancelets (Amphioxus)
• Notochord runs from head through tail
• Muscles can contract the notochord
• Live partially buried in marine sediment
• Filter feeders
• Dioecious