||Sandy or muddy areas dominated by members of the subphylum Urochordata, including
ascidians, sea squirts, and other tunicates. Tunicates are bag-like organisms that
use incurrent and excurrent siphons for filter feeding and respiration. These animals
may be resting on the sediment surface, partially embedded in the sediment, or attached
to conspecifics. On both East and West coasts of the U.S., and in many other areas
worldwide, colonies of the invasive sea squirt Didemnum are rapidly invading
and smothering local biotopes.