Ascidiacea

Paraphyletic class of tunicates comprising sea squirts

Ascidiacea, commonly known as the ascidians or sea squirts, is a paraphyletic class (biology) in the subphylum Tunicata of sac-like marine (ocean) invertebrate filter feeders. Ascidians are characterized by a tough outer test or "tunic" made of the polysaccharide cellulose. Ascidians are found all over the world, usually in shallow water with salinities over 2.5%.

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