Tunicates
Tunicates, also known as sea squirts, are marine animals belonging to the subphylum Tunicata in the phylum Chordata. They are characterized by their unique notochord, or dorsal nerve cord, which is present only during their larval stage. Adult tunicates are sessile filter feeders that live attached to rocks, shells, and other hard surfaces in both shallow and deep waters. They have a soft, gelatinous body enclosed within a protective tunic made of cellulose-like material. Tunicates play an important role in the marine ecosystem by filtering large volumes of water and removing excess nutrients. Despite their simple appearance, tunicates are closely related to vertebrates, sharing many developmental and genetic characteristics with fish, amphibians, reptiles, birds, and mammals.