SHELL UTILIZATION BY THE HERMIT CRABS DIOGENES PUGILATOR (ROUX, l829), PAGURISTES EREMITA (LINNAEUS, l767) AND PAGURUS FORBESII BELL, 1845 (CRUSTACEA: DECAPODA: ANOMURA), IN A SHALLOW-WATER COMMUNITY FROM SOUTHERN SPAIN

摘要

Gastropod shells used by the three dominant hermit crabs, Diogenes pugilator (Roux, l829), Popristes eremita (Linnaeus, l767), and Pagurus forbesii Bell, l845, of the detritic littoral bottoms from Barbate Bay (Cadiz, Spain) were analyzed. The study showed that these hermit crabs species have different patterns ofgastropod shell use. Pagristes eremita, the largest and strongest species, inhabits heavier gastropod shell species with wider aperture (belonging to the Muricidae family), while, Diogenes pugilator and Pagurus forbesii, indabit smaller and lighter shells (mainly those belonging to the family TUrridae). Diogenes pugilator, despite being clearly the more abundant species, does not use the most abundant species of the gastropod conununity (Turritella turbona), which instead is used by Pagurus forbesii. However, no morphological relationships between these her- mit crabs and the diameter of shell aperture have been found either in relation with the Whole gastropod shells used or in relation with the more specifically used shells. On the other hand, specimens of D. pugilator with cephalothoracic shield widths larger than the shell aperture have been found, however, this result has not been found in P.forbesii or in Paguristes eremita. Also, in these three species no differences in shell use by sexes exist. These and other data indicate that D. pugilator does not make a strong shell selection, perhaps in part, due to a competition with P.forbesii and a scarcity of available useful shells in the area, Which are a fundamental limiting factor. On the contrary, P. eremita seems to use adequate shells, a point that allows us to speculate that this species makes (with or without competition with the other hermit crabs) a real selection. Finally, the data about relative growth of the cheliped of D. pugilator in different areas, in Which they use different shells, are similar. These data contrasts with the stunting hypothesis.