The objective of the present study was to characterize the spatial distribution and shell utilization of three hermit crab species in the estuarine-bay complex of São Vicente, São Paulo State, Brazil. Monthly samples were done throughout two years, in the non-consolidated sub-littoral at the estuarine-bay complex. The environmental factors, such as temperature, salinity and depth, were measured every month. The three hermit crab species, Clibanarius vittatus, Loxopagurus loxochelis and Isocheles sawayai, were captured utilizing shells from six gastropods species; 92.7% of the hermit crabs utilized Stramonita haemastoma. The results suggest a strong correlation between hermit crabs spatial distribution and salinity, which was considered the main environmental factor limiting their distribution in the estuary. I. sawayai was the only species present in all transects sampled; C. vittatus was captured only in regions with low salinity and L. loxochelis occurred only in high salinity waters

El objetivo de este estudio fue definir la distribución de tres especies de cangrejo ermitaño y la utilización de conchas en el sublitoral no consolidado del complejo bahía-estuario de São Vicente, Provincia de São Paulo, en Brasil. Las muestras fueron retiradas mensualmente durante dos años consecutivos. Factores ambientales como temperatura, salinidad y profundidad, también fueron registrados todos los meses. Las tres especies de ermitaños Clibanarius vittatus, Loxopagurus loxochelis e Isocheles sawayai fueron capturadas con la utilización de la concha de seis especies de gasterópodos; 92,7% de los individuos utilizaron conchas de Stramonita haemastoma. Los resultados indicaron una fuerte asociación entre la distribución espacial de los ermitaños y la salinidad, que mostró ser el principal factor límite de su distribución en ese estuario. I. sawayai fue la única especie presente en todos los lugares muestreados en este estudio; C. vittatus fue capturado solamente en los lugares de menor salinidad y L. loxochelis estaba presente sólo donde la salinidad se mantuvo con altos niveles

O objetivo do presente estudo foi avaliar a utilização de conchas de gastrópodes por Clibanarius vittatus (Bosc, 1802), na Praia dos Pescadores, em São Vicente (SP), Brasil. Foram realizadas amostras mensais no período de maio de 2001 a abril de 2003, na região intertidal durante a maré baixa. Todos os animais foram pesados e tiveram o comprimento de seu escudo cefalotorácico mensurados, suas conchas identificadas e medidas quanto ao comprimento (mm), abertura (mm) e peso (g). Capturamos 2.344 ermitões (644 machos, 1.594 fêmeas não-ovígeras, 45 fêmeas ovígeras e 61 em intersexo), utilizando 13 espécies de conchas de gastrópodes, das quais Stramonita haemastoma (Linnaeus, 1767), Cymatium parthenopeum (Von Salis, 1793) e Achatina fulica (Bowdich, 1822) representaram mais de 98% das conchas utilizadas. Obteve-se significativa diferença de tamanho entre os sexos, com machos e indivíduos em intersexo atingindo maior porte físico do que fêmeas. Este padrão influenciou fortemente na ocupação e utilização de conchas, principalmente em A. fulica, que foi a maior concha obtida por C. vittatus, utilizada somente por machos e indivíduos em intersexo. Cymatium parthenopeum foi a única espécie de concha em que se obtiveram elevados coeficientes de determinação para todas os parâmetros analisados. Stramonita haemastoma apresentou elevados e significativos coeficientes de determinação, indicando que esta espécie é o principal recurso de concha ocupada na Praia dos Pescadores.

We evaluated the gastropod shell utilization pattern of the hermit crab Clibanarius vittatus (Bosc, 1802) at Pescadores Beach in São Vicente, State of São Paulo, Brazil. Specimens were collected monthly from May 2001 through April 2003, in the intertidal zone at low tide. The crabs were weighed and their carapace shield length measured. All gastropod shells were identified and had their shell biometric parameters (total length and aperture length) measured (mm) and weighed (g). A total of 2,344 hermit crabs (644 males, 1,594 females, 45 ovigerous females and 61 individuals in intersex), using 13 species of gastropod shells, were collected. Stramonita haemastoma (Linnaeus, 1767), Cymatium parthenopeum (Von Salis, 1793) and Achatina fulica (Bowdich, 1822) comprised over 98% of all the shells. Male and intersex crabs were significantly larger than the females. This size difference strongly influenced the shell utilization pattern, principally in A. fulica, which has the largest shell size, that was only used by males and intersexual individuals of C. vittatus. Cymatium parthenopeum was the only shell species that showed a high determinant coefficient in all the biometric correlations evaluated. The high abundance of S. haemastoma shells and a strong correlation between crab size and shell aperture length established by a significant determination coefficient, indicated that C. vittatus uses this species as the principal resource for shell occupation at Pescadores Beach.

Hermit crabs depend on mollusc shells for housing. In this study, an unusual resource is reported for a hermit crab that usually inhabits marine gastropod shells. During a field study conducted from May 2001 to April 2003 in an estuarine area in São Vicente, state of São Paulo, Brazil, 21 individuals of Clibanarius vittatus (Bosc, 1802) were found inhabiting the shells of the terrestrial gastropod Achatina fulica Bowdich, 1822. A. fulica occurs in nearshore grass patches, where occasional contact with sea water kills them, and their shells then become available to the hermit crabs

El cangrejo ermitaño depende de conchas de moluscos para hacer de ella su casa. Este estudio ha descubierto una manera inusual de como vive este cangrejo, que generalmente habita la concha de gastrópodos marinos. El estudio fue realizado en la estación marítima de São Vicente, provincia de São Paulo, de mayo de 2001 hasta abril de 2003. Durante ese periodo, un total de 21 cangrejos Clibanarius vittatus (Bosc, 1802) fueron encontrados viviendo en las conchas del caracol terrestre Achatina fulica Bowdich, 1822. A. fulica ocurre en áreas de césped cercanos a la costa, donde el contacto ocasional con el agua de mar provoca su muerte y sus conchas quedan disponibles para el cangrejo ermitaño