ABSTRACT Crabs use burrows to prevent predation, environmental interference and shelter. The present study investigated the excavation behavior of the trichodactylid crab Dilocarcinus pagei, considering the biometric aspects of the burrows, the excavation time, the amount of bioturbation and the excavation behavior of the two sexes. The burrows of males had a mean diameter larger than the females, although the depth was similar for both sexes. Females had higher bioturbation than males, and showed enlargement in a camera format at the bottom, even closing the entrance of the burrows with a “plug” after their construction. Both the camera and the presence of the “plug” in the burrows of the females may be associated with reproduction. The presence of pellets observed at the entrance of burrows is associated with the cleaning of the pereiopods by crabs after the excavation. The sequence of behaviors for the construction of the burrows is described in detail, contributing to the knowledge about the biology and ecology of freshwater crabs of the Amazon.

Invasões biológicas marinhas são processos naturais acelerados pelas atividades humanas e o siri Charybdis hellerii é um exemplo de espécies invasoras distribuídas pelo mundo. Este estudo avaliou a variação de cor em C. hellerii e sua relação com o sexo, tamanho e maturidade sexual desses indivíduos, e comparou a eficiência de um programa de edição de imagem de licença livre com um programa disponível comercialmente. A cor dos indivíduos foi analisada usando imagem digital padronizada. O padrão de cor variou significantemente com o tamanho; indivíduos pequenos e imaturos são mais escuros que indivíduos maiores e maduros. Os abdomens das fêmeas mudaram morfologicamente e na cor de acordo com a maturidade sexual, tornando-se mais largos e de cor alaranjada. Não houve diferença estatística nos valores de cor entre machos e fêmeas, e machos imaturos não mostraram diferenças morfológicas e de cor em seus abdomens. Este estudo ressalta as possíveis relações da cor e estado fisiológico do sistema reprodutivo o que pode ajudar futuramente em estudos comportamentais, evitando a necessidade de dissecar e/ou remover indivíduos da natureza para avaliar a maturidade sexual. O programa livre obteve a mesma eficiência na análise de imagem digital em relação ao programa comercial amplamente conhecido.

A marine biological invasion is a natural process accelerated by human activities, and the crab Charybdis hellerii is an example of a globally widespread invasive species. This study evaluated color variation in C. hellerii and its relationship to the sex, size and sexual maturity of these crabs, and compared the efficiency of a freeware digital image-editing program with a commercially available program. The color of the individuals was analyzed using standardized digital images. The color pattern varied significantly with size; smaller and immature individuals were darker than larger and mature ones. The female abdomen changed in morphology and color with sexual maturity, becoming wider and orange-colored. There was no statistical difference in the color values between males and females and immature males did not show morphological or color differences in their abdomen. This study highlights the possible relationships of the color and physiological state of the reproductive system, which could help in future studies of behavior, avoiding the need to dissect and/or remove individuals from nature for assessment of sexual maturity. The freeware program showed the same efficiency in digital image analysis as a widely known commercial program.

O caranguejo de manguezal Ucides cordatus é um dos crustáceos mais explorados do Brasil. O presente estudo investigou a época reprodutiva desta espécie e o período do fenômeno da “andada”, quando os caranguejos estão ativos fora das tocas e ocorrem comportamentos agonísticos. Além disso, estes fatores foram relacionados com fatores ambientais em um manguezal da costa brasileira, com inferência sobre o manejo deste caranguejo. Os caranguejos reproduziram de outubro a fevereiro. A “andada” ocorreu de novembro a fevereiro, com características típicas nos primeiros dois meses, durante os períodos de lua cheia e lua nova, e foi influenciada positivamente pela temperatura do ar e do solo, luminosidade e amplitude de maré e negativamente pela salinidade. Baseado nos resultados do presente estudo, o período quando a “andada”ocorre poderia ser definido em outras partes do Brasil, o que auxiliaria no manejo deste recurso pesqueiro. Para Iguape, Estado de São Paulo, Brasil, sugerimos a proibição da pesca para ambos os sexos durante o mês de dezembro ou durante as luas cheia e nova, incluindo o mês de janeiro.

The mangrove crab Ucides cordatus is one of the most exploited crustaceans in Brazil. The present study investigated the breeding season of this species and the period of the “andada” phenomenon, when the crabs are active outside their burrows and perform agonistic behaviors. Furthermore related them to environmental factors, in a mangrove on the coast of Brazil, with inferences about management of this crab. The crabs reproduced from October through February. The “andada” occurred from November through February, with typical characteristics in the first two months, during the full and new moon periods, and was influenced positively by the air and soil temperature, luminosity, and tidal amplitude, and negatively by salinity. Based on the results of the present study, the period when the “andada” occurs in other parts of Brazil could be defined, which will aid in managing this fishery. For Iguape, state of São Paulo, Brazil, we suggest a legal off-season for both sexes in December or during the full and new moon, including January.

Trawl fisheries are associated with catches of swimming crabs, which are an important economic resource for commercial as well for small-scale fisheries. This study evaluated the population biology and distribution of the swimming crab Callinectes ornatus (Ordway, 1863) in the Estuary-Bay of São Vicente, state of São Paulo, Brazil. Crabs were collected from a shrimp fishing boat equipped with a semi-balloon otter-trawl net, on eight transects (four in the estuary and four in the bay) from March 2007 through February 2008. Specimens caught were identified, sexed and measured. Samples of bottom water were collected and the temperature and salinity measured. A total of 618 crabs were captured (332 males, 267 females and 19 ovigerous females), with a sex ratio close to 1:1. A large number of juveniles were captured (77.67%). Crab spatial distributions were positively correlated with salinity (Rs = 0.73, p = 0.0395) and temperature (Rs = 0.71, p = 0.0092). Two peaks of recruitment occurred, in summer and autumn, and ovigerous females were mostly captured during summer, showing a seasonal reproductive pattern. The results showed that C. ornatus uses the bay as a nursery area for juvenile development. Callinectes ornatus is not yet a legally protected species, and the minimum allowed size of crabs caught in the area, although already restricted, should be carefully evaluated since the removal of large numbers of juveniles could negatively impact the local population.

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