''Amphibalanus amphitrite'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of acorn

barnacle A barnacle is a type of arthropod constituting the subclass 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 eros ...

in the

Balanidae The Balanidae comprise a family of barnacles of the order Balanomorpha. As a result of research published in 2021 by Chan et al., the members of the family Archaeobalanidae were merged with this family. Genera These genera belong to the family B ...

family. Its common names include the striped barnacle, the purple acorn barnacle and Amphitrite's rock barnacle. It is found in warm and temperate waters worldwide.

Description

''A. amphitrite'' is a medium-sized, cone-shaped

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

barnacle with distinctive narrow vertical purple or brown stripes. The surface of the test has vertical ribbing. It has a diamond-shaped operculum protected by a movable lid formed from two triangular plates. It grows to about twenty millimetres in diameter.

Distribution

It is uncertain where ''A. amphitrite'' originated but it may have been in the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

or southwestern

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

as fossils of the species have been found in these regions. It has now spread to most of the warm and temperate seas of the world.

Habitat

''A. amphitrite'' is a common coastal and estuarine organism found on hard natural surfaces such as bedrock, boulders, mollusc shells and

red mangrove Red mangrove may refer to at least three plant species: * ''Rhizophora mangle'' * ''Rhizophora mucronata'' * ''Rhizophora stylosa'' {{Short pages monitor