From Wikipedia, the free encyclopedia.
Urochordata (Tunicate worms, "Sea Squirts") are saclike filter feeders with input and output siphons.
Some larval forms appear very much like primitive chordates or hemichordates with a notochord (primitive spinal cord). Some forms have a calcereous spicule that may be preserved as a fossil. Jurassic to Present with one proposed Neoproterozoic form - Yarnemia. Some workers class the Urochordates as a subphylum of the chordata.
