Characterization of the occupied shells by the hermit crab Clibanarius vittatus (Decapoda, Diogenidae) at Baixio Mirim tideflat, Guaratuba Bay, southern Brazil.

A characterization of the occupied shells by the hermit crab Clibanarius vittatus was carried out. Hermit crabs were collected in the intertidal zone, during the low spring tide monthly from April 2005 to March 2006. They were sexed and their cephalothoracic shield length (CL) was measured. Shells were identified, dried, weighed and the aperture length (AL) and width (AW) were measured. 1187 crabs were collected (949 males, 216 females and 22 intersexes), which occupied 12 species of gastropod shells. Stramonita haemastoma, Olivancillaria urceus and Dorsanum moniliferum made up 96.55% of the total shell species. Male hermit crabs attained significantly larger sizes than females; therefore, males occupied a wider spectrum of shells in size and weight. A stronger correlation ratio was obtained between CL and AW of S. haemastoma. Last whorl with a rounded shape and a spacious inner area is a common feature of all shell species most frequently occupied by this hermit crab where it occurs. The successful establishment of C. vittatus at Baixio Mirim is mainly due to the appropriately shaped and wide range of size of S. haemastoma shells that were most often occupied by the hermit crabs of the studied population.

Characterization of the occupied shells by the hermit crab Clibanarius vittatus (Decapoda, Diogenidae) at Baixio Mirim tideflat, Guaratuba Bay, southern Brazil

A characterization of the occupied shells by the hermit crab Clibanarius vittatus was carried out. Hermit crabs were collected in the intertidal zone, during the low spring tide monthly from April 2005 to March 2006. They were sexed and their cephalothoracic shield length (CL) was measured. Shells were identified, dried, weighed and the aperture length (AL) and width (AW) were measured. 1187 crabs were collected (949 males, 216 females and 22 intersexes), which occupied 12 species of gastropod shells. Stramonita haemastoma, Olivancillaria urceus and Dorsanum moniliferum made up 96.55 percent of the total shell species. Male hermit crabs attained significantly larger sizes than females; therefore, males occupied a wider spectrum of shells in size and weight. A stronger correlation ratio was obtained between CL and AW of S. haemastoma. Last whorl with a rounded shape and a spacious inner area is a common feature of all shell species most frequently occupied by this hermit crab where it occurs. The successful establishment of C. vittatus at Baixio Mirim is mainly due to the appropriately shaped and wide range of size of S. haemastoma shells that were most often occupied by the hermit crabs of the studied population.

A caracterização das conchas ocupadas pelo ermitão Clibanarius vittatus (Bosc, 1802) foi realizada. Os ermitões foram coletados de abril/2005 a março/2006, na zona intertidal, durante a maré baixa de sizígia. Os ermitões tiveram o sexo reconhecido e foram medidos no comprimento do escudo ce-falotorácico. As conchas foram identificadas, pesadas depois de secas e edidas no copriento e na largura da abertura. Foram coletados 1187 ermitões (949 machos, 216 fêmeas e 22 intersexos) que ocuparam 12 espécies de conchas de gastrópodes. Stramonita haemastoma, Olivancillaria urceus e Dorsanum moniliferum perfizeram 96,55 por cento do total das conchas ocupadas. Ermitões machos atingiram tamanhos significativamente maiores do que as fêmeas; entretanto ocuparam um maior espectro de conchas em tamanho e peso. Fortes índices de correlação foram obtidos para a relação entre o escudo cefalotorácico dos ermitões e a largura da abertura de S. haemastoma. A última espira espaçosa e de formato globoso é um aspecto comum das conchas mais frequentemente ocupadas pelo presente ermitão em todos os locais de sua ocorrência. O sucesso no estabelecimento de C. vittaus no Baixio Mirim é devido principalmente ao formato e à amplitude de tamanhos das conchas de S. haemastoma, as quais são mais frequentemente ocupadas pelos ermitões da população estudada.