Ī ring of plates surrounds the body, homologous with the carapace of other crustaceans. : 2–3 This natural cement is able to withstand a pulling strength of 5,000 pounds-force per square inch (30,000 kilopascals 400 kilograms-force per square centimetre) and a sticking strength of 22–60 pounds-force per square inch (200–400 kilopascals 2–4 kilograms-force per square centimetre). These glands secrete a type of natural quick cement made of complex protein bonds (polyproteins) and other trace components like calcium. In some barnacles, the cement glands are fixed to a long, muscular stalk, but in most they are part of a flat membrane or calcified plate. Attachment įree-living barnacles are attached to the substratum by cement glands that form the base of the first pair of antennae in effect, the animal is fixed upside down by means of its forehead. Pedunculate barnacles ( goose barnacles and others) attach themselves by means of a stalk. The most common among them, "acorn barnacles" ( Sessilia), are sessile where they grow their shells directly onto the substrate. They have four nektonic (active swimming) larval stages.ĭescription Whale barnacles attached to the throat of a humpback whale Barnacles on a boat propeller.īarnacles are encrusters, attaching themselves temporarily to a hard substrate or a symbiont such as a whale ( whale barnacles), a sea snake ( Platylepas ophiophila), or another crustacean, like a crab or a lobster ( Rhizocephala). They are sessile (nonmobile) and most are suspension feeders, but those in infraclass Rhizocephala are highly specialized parasites on other crustaceans. Around 1,000 barnacle species are currently known.
Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. Barnacles are a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and are hence related to crabs and lobsters.
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