Acanthodoris pilosa

Lore & Background

Acanthodoris pilosa was first described from Norway. Its body is covered with long, fleshy pointed papillae, giving it a fluffy impression. At the head end are two rhinophores, much larger than the papillae, which house sensory organs and typically bend toward the rear. At the posterior end is a distinctive ring of up to nine gills. The uniform color ranges from whitish to pale purplish-brown to darker brown or charcoal grey, and juveniles are often speckled.

Reader's Guide

This species is common all around the British Isles in the shallow subtidal zone, at depths down to about 80 m. It has been reported from the North Atlantic on both American and European coasts, and from the Pacific Northwest. Specimens from Cobscook Bay, Maine and Murles Point, County Donegal, Ireland have been sequenced for the 16S ribosomal RNA, Histone H3 and CO1 genes. Reports from Japan are considered doubtful due to molecular phylogeny results showing that at least some North Pacific animals are Acanthodoris atrogriseata. Ecologically, it is found on rocks and other hard substrates, feeding on encrusting bryozoans.

Did You Know?

• Acanthodoris pilosa grows to about 3 cm, occasionally up to 7 cm.
• It has a distinctive ring of up to nine gills at the posterior end.
• Juveniles are often speckled, while adults have a uniform color.
• Reports from Japan are considered doubtful; some North Pacific specimens are actually Acanthodoris atrogriseata.