''Megabalanus californicus'', the California barnacle, is a species of large

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 erosive ...

in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

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 ...

. It is native to rocky coasts in the Eastern Pacific Ocean from North California to the

Gulf of California The Gulf of California ( es, Golfo de California), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Bermejo''), is a marginal sea of the Pacific Ocean that separates the Baja C ...

Description

''Megabalanus californicus'' is a large acorn barnacle with a diameter of up to . The steep-sided shell is formed of six plates finely striped vertically with reddish-purple and white. There are relatively wide, reddish radii between the plates where they fuse. The mantle, visible through the wide aperture, is margined with red, orange, yellow and blue. This barnacle could be confused with ''

Megabalanus coccopoma ''Megabalanus coccopoma'', the titan acorn barnacle, is a tropical species of barnacle first described by Charles Darwin in 1854. Its native range is the Pacific coasts of South and Central America but it is extending its range to other parts of ...

'', but that species is paler, has a smaller aperture and narrower radii between the plates.

Distribution and habitat

''Megabalanus californicus'' occurs in the Eastern Pacific Ocean in the subtidal and intertidal zones of rocky shores. Its range extends from northern California southwards to the

. It usually grows in groups and is most common on pilings and buoys. In a year following an

El Niño El Niño (; ; ) is the warm phase of the El Niño–Southern Oscillation (ENSO) and is associated with a band of warm ocean water that develops in the central and east-central equatorial Pacific (approximately between the International Date ...

event, it is often found to have increased its distribution northwards.

Biology

In common with related species, ''Megabalanus californicus'' is a hermaphrodite and broadcast spawner. The eggs are retained in the mantle cavity where they are fertilised, the developing nauplii larvae becoming

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cr ...

ic. After six stages these develop into zoea larvae which settle on the seabed, cement themselves to the

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...

and undergo metamorphosis into juveniles.

References

{{Taxonbar, from=Q4291639 Barnacles Crustaceans described in 1916 Crustaceans of the eastern Pacific Ocean