Species description: A white to pink acorn barnacle that grows up to 25 mm. The body is low and made up of 6 plates that are pearly white to grey, with purple or pink striping, and are quite smooth. The opercular aperture is diamond shaped and relatively large. The tergo-scutal flap is white with a hint of pink or yellow, and there are four dark bands crossing it.

Habitat: A warm water species that has so far only been recorded at sites with artificially warmed water (e.g. power stations). Grows on a range of hard substrata. Found both intertidally and subtidally.

Distribution: Not recorded around the island of Ireland to date; most records are from the south coast of Britain.

Similar Species: Could be confused with other 6-plated barnacles that also have diamond-shaped openings such as Semibalanus balanoides, Amphibalanus improvisus and Balanus crenatus, but they do not have the striping on their outer plates or the dark banding on the tergo-scutal flap. Could be confused with Solidobalanus fallax but in A. amphitrite there is a much neater pattern of stripes and four distinctive dark bands running across the tergo-scutal flap.

Key Identification Features:

• White to pink colouration.
• 6 pearly white-grey plates with purple or pink striping.
• Relatively large diamond-shaped opercular opening.
• Four dark bands crossing tergo-scutal flap.

Distribution Map from NBN: Amphibalanus amphitrite at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Amphibalanus amphitrite at iNaturalist World Species Observations database.

WoRMS: Amphibalanus amphitrite at World Register of Marine Species. Accepted name: Amphibalanus amphitrite (Darwin, 1854). AphiaID: 421137.

Classification: Biota; Animalia; Arthropoda; Crustacea; Multicrustacea; Thecostraca; Cirripedia; Thoracica; Thoracicalcarea; Balanomorpha; Balanoidea; Balanidae; Amphibalaninae; Amphibalanus