Linnaeus, 1758
Description
This species is often aptly referred to as "Dead men's fingers".
Mature colonies form thick, fleshy masses of irregular shape, typically produced into stout, finger-like lobes which usually exceed 20 mm diameter; rarely more than 10 lobes per colony. Young, developing colonies form encrustations about 5-10 mm thick (A. digitata encrusting). Height and breadth of colonies up to 200 mm.
Colouration: Several colour varieties occur: white, orange, yellow or brownish, the colour being due to the sclerites; anthocodia translucent white. Ripe gonads, occurring in autumn and winter, are pink and may influence the overall colour.
Habitat
Attached to rocks with little algal cover, shells, stones, and occasionally on living crabs or gastropods. Generally found in situations where strong water movement- currents or wave turbulence-prevails. Frequent on the lower shore but more common sublittorally, down to about 50 m, exceptionally deeper.
Distribution
Common and widespread around all coasts of the British Isles and western Europe in general, from about 41°N to Iceland; records from the east coast of North America may apply to a different species.