Description: A large, steeply conical barnacle with a ‘volcano’ shape which can range from 15 – 50 mm. The outer shell is often white to grey, tinged with pink or purple, which can be in the form of stripes. The 6 plates are strongly built and are often ribbed. The opercular opening is small in relation to the overall size of the animal but can be larger in subtidal animals, the operculum is recessed. The tergo-scutal flap is sheath-like and is brown to purple flecked with white or blue, with a white to pink rim.

Habitat: Found from the mid-shore to subtidal. On rocks and artificial hard substrata, including ships.

Distribution: Most commonly found in SW Britain but there are scattered records from other coasts around Britain and Ireland. Currently very few records from Ireland.

Similar Species: Large size and steeply conical shape should help distinguish this species from other barnacles, although there is a variety of acorn barnacles found in Britain and Ireland that could be confused with each other.

Key Identification Features:

• Large (up to 50 mm), steeply conical barnacle with volcano shape.
• White to grey outer shell which is often tinged with pink or purple.
• Opercular opening relatively small, operculum recessed.
• Tergo-scutal flap a brown to purple sheath flecked with white or blue, with a white to pink rim.

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

iNaturalist: Perforatus perforatus at iNaturalist World Species Observations database.

GBIF data for Perforatus perforatus

WoRMS: Perforatus perforatus at World Register of Marine Species. Accepted name: Perforatus perforatus (Bruguière, 1789). AphiaID: 535477.

Classification: Biota; Animalia; Arthropoda; Crustacea; Multicrustacea; Thecostraca; Cirripedia; Thoracica; Thoracicalcarea; Balanomorpha; Balanoidea; Balanidae; Concavinae; Perforatus