Calliactis parasitica

(Couch, 1842)

Diameter of base up to 80 mm, height to 100 mm.
Base a little wider than the column, capable of firm adhesion.
Column not divided into regions and without tubercles, its surface rough and leathery, with a grainy appearance. Sometimes patches of thin periderm are present. Cinclides fairly prominent, occurring on small mounds in a zone just above the limbus, one on each endocoel; acontia are readily emitted from them when the anemone is disturbed.
Disc concave, fairly wide when fully expanded.
Tentacles: Tentacles moderate in length and very numerous, hexamerously arranged, up to at least 700 in a large specimen.
Colouration: Ground colour of column pale buff, yellowish, or light brown. It is more or less densely freckled brown or reddish, the freckles tending to form longitudinal stripes, these being subdivided proximally by short vertical lines of yellowish cream which lie on the endocoels and run upward for a short distance from the limbus. The overall effect is variable; sometimes the dark stripes are indistinct; often irregular blotches and spots of black, brown, purplish or red occur amongst the other colours breaking up the striped effect, sometimes these alone are present. Disc and tentacles translucent cream or yellowish, occasionally orange, usually with a simple pattern of opaque cream on the disc, the tentacles each with two broken longitudinal lines of reddish brown, often with tiny cream spots in the interruptions.

Usually found in association with the hermit crab Pagurus bernhardus (Linnaeus), often with more than one anemone on the gastropod shell inhabited by the crab. May also occur on other substrata such as other crabs (e.g. Maia) or on stones, etc. Typically a sublittoral species occurring down to about 60 m but occasionally found on the shore in sheltered localities, or washed up by storms.

Common in the English Channel but not extending much further north than the Bristol Channel or southern Ireland; records from the southern part of the North Sea are very dubious. Common around south-west Europe and in the Mediterranean, where it may be associated with other species of hermit crab.