Onchidoris muricata (Müller, 1776)

12 April, 2003.
East coast of Hyskeir Island on the west coast. 
Water temperature 10° C. At 7 metres, two of several animals found on the kelp browsing on the bryazoan Membranipora membranacea.
Nikon 90SX with 105mm lens in Subal housing and housed SB26 flash.

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nudibranchs of the british isles sea slug forum