Abstract
Among more than 800 known species of hermit crabs very few have been reported to be able to occupy both spiral and straight microhabitats, i.e., gastropod and scaphopod shells, worm tubes, etc. These species are of interest for understanding the effects of microhabitats on crab morphology.
During routine work with large collections of Parapaguridae, I found specimens of at least five species occupying either gastropod or scaphopod shells: Parapagurus pilosimanus, Parapagurus sp., Sympagurus dimorphus. Oncopagurus minutus. and O. monstrosus. These species usually use spiralled microhabitats, and only rarely straight shells. Differences in uropod and telson symmetry and in pleopod morphology in specimens of similar size of each species, living in straight and spiral habitats were analyzed. The small number of specimens examined does not allow to present a clear conclusion, but it seems that for species that normally live in gastropod shells, living in a straight shell does not or only slightly influence telson and uropod symmetry.