Barnacle Barnacle A barnacle is a type of arthropod constituting the infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile (nonmotile) suspension feeders, and have two nektonic (active swimming) larval stages. Around 1,220 barnacle species are currently known. The name "Cirripedia" is Latin, meaning "curl-footed". The study of barnacles is called cirripedology. Barnacles are encrusters, attaching themselves permanently to a hard substrate. The most common, "acorn barnacles" (Sessilia), are sessile, growing their shells directly onto the
Ivory barnacle Ivory barnacle Amphibalanus eburneus, the ivory barnacle, is a species of acorn barnacle in the family Balanidae. It occurs on the east coast of North America, the Caribbean Sea and Gulf of Mexico. The ivory barnacle is a medium-sized, cone-shaped sessile barnacle with a white test composed of fused plates. It has a diamond-shaped operculum protected by a hinged lid formed from two triangular halves each consisting of two plates, a tergum and a scutum. It can grow to a height of but most individuals are much smaller. This barnacle can be confused with the white bay barnacle ("Balanus improvisus")