Acrothoracica

(invertebrate zoology) A small order of burrowing barnacles in the subclass Cirripedia that inhabit corals and the shells of mollusks and barnacles.

An order of the subclass Cirripedia. All members burrow into shells of mollusks and thoracican barnacles, echinoderm tests, polyzoans, dead coral, and limestone. The normal three pairs of cirriped mouthparts are present: mandibles, maxillules, and maxillae. Four to six pairs of cirri occur, often greatly reduced in size, the first pair close to the oral appendages and the remainder packed together at the posterior end of the body. The sexes are separate; dwarf males are found on the mantle or wall of the burrow of the female. Naupliar larval stages may be omitted, but a cypris larva always occurs in the life cycle. Three families, about eight genera, and 40 species are recognized. See also Cirripedia.