Main Page | See live article | Alphabetical index 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. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.