Balanus perforatus is a cirripedia with a base reaching 3 cm in diameter and
up to 5 cm for deeper specimens. The external plates are vertically ribbed.
Their pointed ends as well as the conical organization of the plates evoke the form of a small
volcano. They are greyish with shades of purple or pink. The operculum that closes the upper aperture
is depressed inside the cone formed by the plates. This operculum consists of two pairs of movable plates
that open to allow the cirri out so that the barnacle could catch food. In case of emergency or during
emersed periods, the operculum is kept hermetically closed thanks to a brown or purple flap with blue
and white patches. The common barnacle generally lives in groups attached to rocks or immersed structures such
as ships' bottom.
It is found from surface to 20 meters deep in the Atlantic Ocean from West Africa to Wales, in the English
Channel and in the Mediterranean Sea.
Phylum Arthropoda, sub-phylum Crustacea, class Maxillopoda, order Sessilia, family Balanidae, Balanus perforatus Bruguiére, 1789.
Cirri: Small appendages resembling feathery tentacles.
Photograph: © Wilfried Bay-Nouailhat. Published with author's kind permission.
Balanus perforatus, Bay of Concarneau, South-Brittany, West of France. Depth 3 meters.
Text: Anne Bay-Nouailhat © 2007-2008.
Translation: Anne Bay-Nouailhat © 2007-2008.
