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Barnacles and Relatives: Thecostraca

Physical Characteristics, Habitat, Behavior And Reproduction, Barnacles, Their Relatives, And People, No Common Name (trypetesa Lampas): Species AccountsGEOGRAPHIC RANGE, DIET, CONSERVATION STATUS

NO COMMON NAME (Trypetesa lampas): SPECIES ACCOUNTS
ROCK BARNACLE (Semibalanus balanoides): SPECIES ACCOUNTS

Barnacles and their relatives are found worldwide in oceans and estuaries (EHS-chew-AIR-eez), where rivers meet the sea.

Most barnacles eat algae (AL-jee), bacteria, tiny animals, and bits of other organisms floating in the surrounding water. Some stalked species prey on larger floating animals by capturing them with a single limb, or cirrus (SIH-ruhs). Parasitic thecostracans eat the tissues and fluids of their hosts.


Two species of thecostracans—barnacles Armatobalanus nefrens and Balanus aquila—are listed by the World Conservation Union (IUCN) as Data Deficient. This means there is not enough information to make a judgment about their threat of extinction.

Additional topics

Animal Life ResourceMollusks, Crustaceans, and Related Species