Short- and long-term salinity challenge, osmoregulatory ability, and (Na+, K+)-ATPase kinetics and α-subunit mRNA expression in the gills of the thinstripe hermit crab Clibanarius symmetricus (Anomura, Diogenidae).

The evolutionary history of the Crustacea reveals ample adaptive radiation and the subsequent occupation of many osmotic niches resulting from physiological plasticity in their osmoregulatory mechanisms. We evaluate osmoregulatory ability in the intertidal, thinstripe hermit crab Clibanarius symmetricus after short-term exposure (6 h) or long-term acclimation (10 days) to a wide salinity range, also analyzing kinetic behavior and α-subunit mRNA expression of the gill (Na+, K+)-ATPase. The crab strongly hyper-regulates its hemolymph at 5 and 15‰S (Salinity, g L-1) but weakly hyper-regulates up to ≈27‰S. After 6 h exposure to 35‰S and 45‰S, C. symmetricus slightly hypo-regulates its hemolymph, becoming isosmotic after 10 days acclimation to these salinities. (Na+, K+)-ATPase specific activity decreases with increasing salinity for both exposure periods, reflecting physiological adjustment to isosmoticity. At low salinities, the gill enzyme exhibits a single, low affinity ATP binding site. However, at elevated salinities, a second, high affinity, ATP binding site appears, independently of exposure time. (Na+, K+)-ATPase α-subunit mRNA expression increases only after 10 days acclimation to 5‰S. Our findings suggest that hemolymph hyper-regulation is effected by alterations in enzyme activity during short-term exposure, but is sustained by increased mRNA expression during long-term acclimation. The decrease in gill (Na+, K+)-ATPase activity seen as a consequence of increasing salinity appears to underlie biochemical adjustments to hemolymph isosmoticity as hypo-regulatory ability diminishes.

First zoeal stage of the hermit crab Enallopaguropsis guatemoci (Glassell, 1937) (Crustacea: Anomura: Paguroidea: Paguridea) obtained in the laboratory.

The first larval stage of Enallopaguropsis guatemoci is described in detail and illustrated. The larva is compared with larvae known for other genera of Paguridae except Pagurus. A synthesis of all characters provided herein indicates that first larvae of E. guatemoci can be separated from all known pagurid larvae (except Pagurus) by the combination of the following characters: carapace with long dorsal carina, posterolateral spines absent; abdominal somites 3-5 with pair of moderately long spines; telson narrowly triangular, not forked; spine at antennal protopod as long as endopod.

An unusual new species of paguroid (Crustacea, Anomura, Paguridae) from deep waters of the Gulf of Mexico.

A new hermit crab species of the family Paguridae, Tomopaguropsisahkinpechensis sp. n., is described from deep waters (780-827 m) of the Gulf of Mexico. This is the second species of Tomopaguropsis known from the western Atlantic, and the fifth worldwide. The new species is morphologically most similar to a species from Indonesia, Tomopaguropsiscrinita McLaughlin, 1997, the two having ocular peduncles that diminish in width distally, reduced corneas, dense cheliped setation, and males lacking paired pleopods 1. The calcified figs on the branchiostegite and anterodorsally on the posterior carapace, and the calcified first pleonal somite that is not fused to the last thoracic somite, are unusual paguroid characters. A discussion of the affinities and characters that define this new species is included, along with a key to all five species of Tomopaguropsis.

Gastropod shells used by Dardanus insignis (Decapoda, Anomura) near islands in the Ubatuba region, São Paulo, Brazil / Conchas de gastrópodos utilizadas por Dardanus insignis (Decapoda, Anomura) próximas de ilhas de região de Ubatuba, São Paulo, Brasil

The use of gastropod shells by hermit crabs is determined by the availability of shells in the environment or through selection for size and volume. This study analyzed patterns in the use of shells by Dardanus insignis (Saussure, 1858). From January 1998 to December 1999, 386 individuals were collected from two islands at Ubatuba, São Paulo. The crabs were measured for cephalothoracic shield length (CSL) and wet weight (CWW). The gastropod shells occupied by hermit crabs were identified, and the shell aperture width (SAW), dry weight (SDW) and internal volume (SIV) were measured. The relationships between the dimensions of the gastropod shell and the hermit crabs were evaluated by linear regression analysis. Among the 11 species of gastropod shells used by D. insignis, the most often used was Olivancillaria urceus (31%), followed by Strombus pugilis (22%) and Siratus tenuivaricosus (18%). The shell of O. urceus was used most probably due to its high availability on Couves and Mar Virado islands. The most significant biometric parameter was shell aperture width (F=18.231; p<0.0001), highlighting the importance of this variable for the shell choice by D. insignis at both sites.

O uso de conchas de gastrópodos por ermitões se dá de acordo com a disponibilidade no ambiente ou através de mecanismos seletivos relacionados, como o tamanho e volume. O objetivo deste trabalho foi analisar os padrões do uso de conchas por Dardanus insignis (Saussure, 1858). Durante o período de janeiro de 1998 a dezembro de 1999 foi coletado um total de 386 indivíduos em duas ilhas pertencentes à Ubatuba, São Paulo, os quais foram medidos de acordo com o comprimento do escudo cefalotoracico (CEC) e o peso úmido (PA). As conchas ocupadas pelos ermitões foram identificadas e mensuradas quanto a largura de abertura (LAC), peso (PSC) e volume interno da concha (VIC). As relações entre as variáveis da concha de gastrópodo e o ermitão, foram avaliadas através da análise de regressão linear. Dentre as onze espécies de concha de gastrópodes utilizadas por D. insignis, a mais usada foi Olivancillaria urceus (31%), seguida por Strombus pugilis (22%) e Siratus tenuivaricosus (18%). A concha de O. urceus foi a mais utilizada, provavelmente devido a sua maior disponibilidade na ilha das Couves e do Mar Virado. Os resultados mostraram que dos parâmetros biométricos mensurados das conchas, o mais significativo foi largura da abertura da concha (F=18.231; p<0.0001), evidenciando a importância desta variável para a escolha das conchas por D. insignis nos dois locais.

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

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.

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 and reproductive features of the western Atlantic hermit crab Pagurus criniticornis (Anomura, Paguridae) from Anchieta Island, southeastern Brazil

The population of the hermit crab Pagurus criniticornis (Dana, 1852) was studied based on seasonal abundance, size frequency distribution, sex ratio, reproductive period, fecundity and shell relationship. Specimens were collected monthly by SCUBA diving in the infralittoral area of Anchieta Island, Ubatuba. A total of 1,017 individuals was analyzed. Animal size (minimum and maximum shield length, respectively) was 0.7 and 2.9 mm for males, 0.6 and 2.8 mm for non-ovigerous females, and 1.0 and 2.5 mm for ovigerous females. The sex ratio was 1:1.29. Sexual dimorphism was recorded by the presence of males in the largest size classes. Ovigerous females were captured during all months along the year, with percentages varying from 8% (July) to 84.3% (February) in relation to the total females collected. Mean ± SD fecundity was 168 ± 125 eggs and tended to increase with increasing hermit size. Shells of four gastropod species [Cerithium atratum (Born, 1778), Morula nodulosa (Adams, 1845), Anachis lyrata (Sowerby, 1832) and Modulus modulus (Linnaeus, 1758)] were occupied by ovigerous females of P. criniticornis but fecundity was not significantly different in relation to the different shell types. The profile showed continuous and intense reproduction of P. criniticornis probably related to strategies developed to compensate for interspecific competition in the studied insular area.

A população do ermitão Pagurus criniticornis (Dana, 1872) foi avaliada com base na abundância sazonal, distribuição da freqüência de tamanho, razão sexual, período reprodutivo, fecundidade e relação com a concha ocupada. Os espécimes foram coletados mensalmente por meio de mergulho autônomo no infralitoral da Ilha Anchieta, Ubatuba. Um total de 1.017 indivíduos foi analisado. O tamanho dos animais (comprimento mínimo e máximo do escudo cefalotorácico, respectivamente) foi de 0,7 e 2,9 mm para os machos, 0,6 e 2,8 mm para as fêmeas não ovígeras e 1,0 e 2,5 mm para as fêmeas ovígeras. A razão sexual foi de 1:1,29. Foi observado dimorfismo sexual em função da presença de machos nas maiores classes de tamanho. Fêmeas ovígeras foram capturadas em todos os meses do ano, com a porcentagem variando de 8% (Julho) a 84,3% (Fevereiro) em relação ao total de fêmeas coletadas. A fecundidade média foi de 168 ± 125 ovos e tendeu a ser maior com o aumento do tamanho do ermitão. Fêmeas ovígeras de P. criniticornis foram encontradas ocupando quatro espécies de conchas de gastrópodes [Cerithium atratum (Born, 1778), Morula nodulosa (Adams, 1845), Anachis lyrata (Sowerby, 1832) e Modulus modulus (Linnaeus, 1758)] no entanto, a fecundidade não foi significativamente diferente em relação aos diferentes tipos de conchas. A população de P. criniticornis apresentou um perfil reprodutivo contínuo e intenso, possivelmente relacionado a estratégias de desenvolvimento que compensam a competição interespecífica existente na área de estudo.

Population and reproductive features of the western Atlantic hermit crab Pagurus criniticornis (Anomura, Paguridae) from Anchieta Island, southeastern Brazil

The population of the hermit crab Pagurus criniticornis (Dana, 1852) was studied based on seasonal abundance, size frequency distribution, sex ratio, reproductive period, fecundity and shell relationship. Specimens were collected monthly by SCUBA diving in the infralittoral area of Anchieta Island, Ubatuba. A total of 1,017 individuals was analyzed. Animal size (minimum and maximum shield length, respectively) was 0.7 and 2.9 mm for males, 0.6 and 2.8 mm for non-ovigerous females, and 1.0 and 2.5 mm for ovigerous females. The sex ratio was 1:1.29. Sexual dimorphism was recorded by the presence of males in the largest size classes. Ovigerous females were captured during all months along the year, with percentages varying from 8% (July) to 84.3% (February) in relation to the total females collected. Mean ± SD fecundity was 168 ± 125 eggs and tended to increase with increasing hermit size. Shells of four gastropod species [Cerithium atratum (Born, 1778), Morula nodulosa (Adams, 1845), Anachis lyrata (Sowerby, 1832) and Modulus modulus (Linnaeus, 1758)] were occupied by ovigerous females of P. criniticornis but fecundity was not significantly different in relation to the different shell types. The profile showed continuous and intense reproduction of P. criniticornis probably related to strategies developed to compensate for interspecific competition in the studied insular area.

A população do ermitão Pagurus criniticornis (Dana, 1872) foi avaliada com base na abundância sazonal, distribuição da freqüência de tamanho, razão sexual, período reprodutivo, fecundidade e relação com a concha ocupada. Os espécimes foram coletados mensalmente por meio de mergulho autônomo no infralitoral da Ilha Anchieta, Ubatuba. Um total de 1.017 indivíduos foi analisado. O tamanho dos animais (comprimento mínimo e máximo do escudo cefalotorácico, respectivamente) foi de 0,7 e 2,9 mm para os machos, 0,6 e 2,8 mm para as fêmeas não ovígeras e 1,0 e 2,5 mm para as fêmeas ovígeras. A razão sexual foi de 1:1,29. Foi observado dimorfismo sexual em função da presença de machos nas maiores classes de tamanho. Fêmeas ovígeras foram capturadas em todos os meses do ano, com a porcentagem variando de 8% (Julho) a 84,3% (Fevereiro) em relação ao total de fêmeas coletadas. A fecundidade média foi de 168 ± 125 ovos e tendeu a ser maior com o aumento do tamanho do ermitão. Fêmeas ovígeras de P. criniticornis foram encontradas ocupando quatro espécies de conchas de gastrópodes [Cerithium atratum (Born, 1778), Morula nodulosa (Adams, 1845), Anachis lyrata (Sowerby, 1832) e Modulus modulus (Linnaeus, 1758)] no entanto, a fecundidade não foi significativamente diferente em relação aos diferentes tipos de conchas. A população de P. criniticornis apresentou um perfil reprodutivo contínuo e intenso, possivelmente relacionado a estratégias de desenvolvimento que compensam a competição interespecífica existente na área de estudo.

Shell utilization pattern of the hermit crab Clibanarius vittatus (Crustacea, Anomura) in an estuary at São Vicente, State of São Paulo, Brazil

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.

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.

Shell utilization pattern of the hermit crab Clibanarius vittatus (Crustacea, Anomura) in an estuary at São Vicente, State of São Paulo, Brazil

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.

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.

The influence of shell species and size on the shell selection pattern of Paguristes tortugae (Decapoda, Diogenidae) from Anchieta Island (Ubatuba, Brazil)

Shell selection by the hermit crab Paguristes tortugae Schmitt, 1933 from Anchieta Island (Brazil) was analyzed using the six most frequently occupied shell species in the field and taking into account the sexual condition of the individuals, the shell size and the shell species. The experiments were conducted under laboratory conditions and the shell species preference was estimated on the basis of the frequency that each species was chosen by the individuals. The preferred shell species and size were determined by regression analysis. The highest correlation coefficients were obtained for the relations between the hermit dimensions and shell dry weight. The ovigerous females preferred shells with larger internal volume: Leucozonia nassa (Gmelin, 1791) and Cerithium atratum (Born, 1778). In the experiment of shell size, males preferred heavier shells whereas females selected the shape characteristics of the shell, such as the aperture and the internal volume, which are probably related to the growth and offspring guarantee, respectively. In general, and independent of sex condition, P. tortugae showed significant selection among all shells utilized. The results suggest that shell selection by P. tortugae involves sexual and reproductive condition preferences.

The influence of shell species and size on the shell selection pattern of Paguristes tortugae (Decapoda, Diogenidae) from Anchieta Island (Ubatuba, Brazil)

Shell selection by the hermit crab Paguristes tortugae Schmitt, 1933 from Anchieta Island (Brazil) was analyzed using the six most frequently occupied shell species in the field and taking into account the sexual condition of the individuals, the shell size and the shell species. The experiments were conducted under laboratory conditions and the shell species preference was estimated on the basis of the frequency that each species was chosen by the individuals. The preferred shell species and size were determined by regression analysis. The highest correlation coefficients were obtained for the relations between the hermit dimensions and shell dry weight. The ovigerous females preferred shells with larger internal volume: Leucozonia nassa (Gmelin, 1791) and Cerithium atratum (Born, 1778). In the experiment of shell size, males preferred heavier shells whereas females selected the shape characteristics of the shell, such as the aperture and the internal volume, which are probably related to the growth and offspring guarantee, respectively. In general, and independent of sex condition, P. tortugae showed significant selection among all shells utilized. The results suggest that shell selection by P. tortugae involves sexual and reproductive condition preferences.