What is Tunicate?
{{Taxobox | name = Tunicata | image = Sea-tulip.jpg | image_width = 230px | image_caption = Sea tulips, ''Pyura spinifera''. <br/>A [[symbiosis|symbiotic]] [[sponge]] covers its surface. | regnum = [[Animal]]ia | phylum = [[Chordata]] | subphylum = '''Tunicata''' | subphylum_authority = Giribet et al 2000 | subdivision_ranks = [[Class (biology)|Classes]] | subdivision = }} [[File:Bluebell tunicates Nick Hobgood.jpg|thumb|right|250px|Bluebell tunicates]] [[Image:Botrylloides violaceus.jpg|thumb|250px|right|Colonies of tunicate ''Botrylloides violaceus''. Note new [[zooid]] buds within colonies and along margins of colonies.]] [[File:Tunicate colony Nick Hobgood.jpg|thumb|250px|right|Colony of ''Botryllus''.]] '''Tunicates''' ('''sea squirts''' or '''Urochordata''') are a [[phylum|subphylum]] of the [[Chordate]]s. They are sea [[filter]]-feeders: they live mainly on [[plankton]]. They are called tunicates because the adult form is covered by a [[leather]]y [[tunic]]. This tunic supports and protects the animal. The adults are [[sessile]], stuck to [[Rock (geology)|rocks]]. Many tunicates are [[colony (biology)|colonial]] or semi-colonial in their adult stage. They are quite a large group, containing about 3,000 [[species]]. The adults live mostly on the sea floor, in the [[littoral zone]]. == Feeding == The sea squirt has two openings in its small body. One opening, called the ''oral siphon'', sucks water into the animal; the other opening, called the ''atrial siphon'', squirts water out of the animal. Inside is a little basket-like [[sieve]] which traps food: so these sea squirts are filter feeders. The Sea squirt can close the holes in its siphons, like a drawstring can close the opening in a bag. == Life cycle == When in its [[larvae|larval state]], it looks like a [[tadpole]] and is sometimes called a ''tadpole larva''. Like many sea creatures, a sea squirt larva looks very different from an adult sea squirt. The larva swims for a short time and then attaches itself to something on the sea floor, like