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
Whale barnacle The goose barnacle "Conchoderma auritum" often attaches to the shell of "C. diadema". Whale barnacles and whales have a commensal relationship–the barnacle benefits at no benefit nor cost to the whale. However, callosities could be an adaptation to prevent barnacles from adding to drag by concentrating infestations, and a heavy infestation may lead to eczema. "Xenobalanus" can more easily grow on sick skin with a weakened immune system, and younger individuals tend to have larger infestations presumably because they are less resistant; further, given it has a stalk, it increases the drag felt by the host and may be considered