The habits and habitats of the opisthobranch molluscs of the British Solomon Islands

Abstract

Often bizarre in shape and gaudily coloured, the opisthobranchs of the tropical IndoPacific have always been attractive subjects for the specialist worker and for writers of popular natural history. There is certainly no lack of papers describing their anatomy and systematics (Marcus & Burch (1965) give a fairly full bibliography), but only in those by Risbec (1928 a, b , 1951, 1953) are there descriptions of where or how they live and his statements are brief and rather vague. I collected opisthobranchs so as to record them for the British Solomon Islands for the first time and, whenever possible, I noted their habits and habitats. My observations on gut contents are rather scanty as I did not wish to damage any of the few specimens of each species collected. From an examination of ten different types of reef formation I discovered that opisthobranchs are common in only two places; (1) the crest of a semi-exposed reef where algae occur in pools, and (2) the flat of a sheltered or semi-sheltered reef. At each of these sites several distinct habitats can be distinguished. Unfortunately my recognition of these habitats is not supported by strong numerical evidence as none of the 55 species occurred in large numbers.