Ascideiacea
From Free net encyclopedia
{{Taxobox
| color = pink
| name = Ascidiacea
| image = Sea-tulip.jpg
| image_width = 250px
| image_caption = Sea Tulips, Pyura spinifera
| regnum = Animalia
| phylum = Chordata
| subphylum = Urochordata
| classis = Ascidiacea
| classis_authority = Nielsen, 1995
| subdivision_ranks = Orders
| subdivision =
Aplousobranchia
Enterogona
Phlebobranchia
Pleurogona
Stolidobranchia
}}
Ascidiacea (commonly known as the ascidians or sea squirts) is a class in the Tunicata subphylum of sac-like marine filter feeders. They are characterized by a tough outer "tunic" made of the polysaccharide tunicin whilst other tunicates are much less robust. Whilst adults are sessile (immobile), larvae resemble tadpoles and swim up and down in their marine environment. The larvae undergo a metamorphosis when a suitable place to attach is found. During this metamorphosis, the tail, along with the notochord and neural tube is reabsorbed, that is why tunicates are also referred as "urochordates" (uro=tail).
Like other tunicates, they also collect and concentrate vanadium in their blood, although the reason for this behaviour is not properly understood.
Examples of ascidians include Sea Tulips and the Solitary Ascidian.
References
- {{cite book
| author = Colin Tudge | year = 2000 | title = The Variety of Life | publisher = Oxford University Press | id = ISBN 0198604262 }}
External link
- Ascideiacea.com - Classification and images of many ascideians.da:Søpunge