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( Tunicata)
Ascidiacea (2,300 species)
Thaliacea
Appendicularia
Sorberacea Tunicates are considered the closest relatives to the Craniata clade (i.e. hagfish and vertebrates), replacing lancelets, which were once considered in that position.[2] Most tunicates are hermaphrodites. The eggs are kept inside their body until they hatch, while sperm is released into the water where it fertilizes other individuals when brought in with incoming water. Some larval forms appear very much like primitive chordates or hemichordates with a notochord (primitive spinal cord). Superficially the larva resemble small tadpoles. Some forms have a calcereous spicule that may be preserved as a fossil. They have appeared from the Jurassic to the present, with one proposed Neoproterozoic form, Yarnemia.
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Tunicata Subcategories
Tunicata Articles
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