Growth of the hermit crab Clibanarius vittatus (Bosc, 1802) (Crustacea, Anomura, Diogenidae) at São Vicente, São Paulo, Brazil

Abstract

The present study analyzed the growth of males and females of the hermit crab Clibanarius vittatus (Bosc, 1802), at São Vicente, São Paulo, Brazil. Monthly collections were made from May/2001 through April/2003, at the Pescadores Beach in São Vicente. The 2,501 crabs caught were identified and sexed and the carapace shield length (CSL) was measured. For the seasonal growth study, the population was divided into 5mm size classes (CSL) and analyzed by the Bertalanffy method, with the aid of the program Fisat II. The mean sizes of the 703 males and 1,798 females were 8.94±1.80 and 6.61±1.13 mm, respectively. A seasonal growth pattern was observed, with males reaching an asymptotic size (14.92 mm) larger than that of females (13.85 mm). Males began the growth process approximately five months before the females. This growth pattern probably helped to reduce intraspecific competition for the shells, because the males reached larger size and made the smaller shells available to the females.<br>O presente estudo teve como objetivo analisar o crescimento de machos e fêmeas do ermitão Clibanarius vittatus (Bosc, 1802), da região de São Vicente, São Paulo, Brasil. Foram realizadas coletas mensais de maio/2001 a abril/2003, na Praia dos Pescadores em São Vicente. Os 2.501 animais capturados foram identificados, determinados quanto ao sexo e mensurados quanto ao seu comprimento de escudo cefalotorácico (CEC). Para o estudo sazonal do crescimento, a população foi dividida em classes de tamanho de 5mm de (CEC), e analisada pelo método de Bertalanffy, com o auxílio do software Fisat II. Foram obtidos 703 indivíduos machos e 1.798 fêmeas, com média de tamanho de 8.94±1.80 e 6.61±1.13mm, respectivamente. Constatou-se um padrão de crescimento sazonal, com machos atingindo um tamanho assintótico (14.92mm) superior ao das fêmeas (13.85mm), além de iniciarem o processo de crescimento aproximadamente cinco meses antes destas. Desta forma, é provável que este seja um padrão que auxilia na diminuição da disputa intra-específica por conchas, uma vez que os machos atingiram maior tamanho e estariam disponibilizando conchas menores para as fêmeas

Population biology and reproduction of the hermit crab Clibanarius vittatus (Decapoda: Anomura) in an estuarine region of southern Brazil

“…A similar absence of juvenile individuals was noted by Turra & Leite (2000), who studied three sympatric species of hermit crabs of the genus Clibanarius, on another part of the Brazilian coast. As estimated by these authors, the recruitment period (December to March, according to Sant'Anna et al, 2008) was equivalent to those months when greater reproductive activity was observed in this population.…”

“…In this population of C. vittatus in São Vicente Estuary, the differential growth rate between the sexes (as proposed by Abrams, 1988) suggests an important factor for the sexual dimorphism. According to the growth analysis of this same population by Sant'Anna et al (2008), males have a larger constant growth than do females (males, K = 0.51; and females, K = 0.40), and the different growth periods of the sexes reduce intraspecific competition for gastropod shells. A slower growth rate of females would be a consequence of utilization of relatively small shells in nature, as suggested by Litulo (2005 a, c) for Dardanus deformis (H. Milne-Edwards, 1836) and Clibanarius longitarsus (De Haan, 1849), respectively.…”

“…This author suggested four explanations for this pattern of the sex-ratio: (1) differences between the sexes in longevity and time for growth; (2) differential migration; (3) different mortality or growth rates between sexes; and (4) sex reversal. In C. vittatus , the most probable causes are the difference in the growth rates between the sexes, with an influence of longevity (Sant'Anna et al , 2008) or habitat partitioning as suggested by Turra & Leite (2000). Sex reversal occurs in a low percentage of C. vittatus populations (see present study and Turra & Leite, 2000), representing a third and minor cause of the sex-ratio pattern observed, and there still is no explanation for the mechanism of sex reversal in hermit crabs (Turra & Leite, 2000; Turra, 2004).…”

Spatiotemporal distribution and population structure of Clibanariussymmetricus(Randall, 1840) (Crustacea, Diogenidae) in an Amazon estuary

“…Temperature is considered the principal abiotic factor determining reproductive patterns in this species; it also acts as a regulator of metabolic, biochemical, and hormonal activity (Sant' Anna et al, 2009). Salinity is also a factor determining the abundance and distribution of C. symmetricus (Sant' Anna et al, 2006a), given that ovigerous females tend to migrate to more saline waters (Sant' Anna et al, 2008). Other factors may also affect the distribution of these organisms in the environment, e.g., type of substrate (Fransozo et al, 1998;Meireles et al, 2006) and the availability of gastropod shells in the environment (Meireles et al, 2003;Biagi et al, 2006a).…”