Acanthodoris pilosa nudibranch
Nudibranch taken on Port St Mary Ledges, Isle of Man.
Photo copyright Tim Nicholson.
This "fluffy" nudibranch has a large crown of gills at its rear which are unseen in this photo. Its usual prey includes the bryozoan "Sea Chervil" (Alcyonidium diaphanum). It grows up to 5 cm long. You find Acanthodoris pilosa in the Northern Atlantic on both the European and American coasts. It is especially common in the British Isles Colour varies from white through to brown, black and even purple.
Further Reading
Great British Marine Animals, by Paul Naylor, Deltor (2011)
The Underwater Photographer: Digital and Traditional Techniques, by by Martin Edge, Paperback, 536 pages (2009)