Epibiont occurrence on gastropod shells used by the hermit crab Loxopagurus loxochelis (Anomura: Diogenidae) on the northern coast of São Paulo, Brazil

Abstract

ABSTRACT. Gastropod shells occupied by hermit crabs are an important attachment substrate for epifauna, and these shells are often damaged. The present study aimed to characterize the epibionts and extent of damage for gastropod shells occupied by the hermit crab Loxopagurus loxochelis (Moreira, 1901). Samples were collected monthly over a period of one year (from July 2002 through June 2003), in the Caraguatatuba and Ubatuba regions, on the northern coast of São Paulo, Brazil. The sampling was performed using a fishing boat equipped with double-rig nets. The shells were identified and weighed. Loxopagurus loxochelis occupied 14 gastropod shell species in Caraguatatuba and five in Ubatuba. In the two areas, approximately 55% of these gastropod shells bore epibionts, and a significantly large number (p < 0.05) showed no damage. The presence of epibionts did not significantly change the mean weight of shells. This cover may provide camouflage to the animals when they are associated with the sandy substrate, which possibly affects the occupancy of the shells by the hermit crabs. Undamaged shells may reflect a high availability of shells in good condition in the environment.

Characterization of epibionts associated with gastropod shells inhabited by Isocheles sawayai (Crustacea: Decapoda: Anomura) on the north coast of Santa Catarina

“…Bryozoans were the most abundant epibionts in our study. A similar pattern of occupation of shells by 2 species of hermit crabs was found on the Brazilian (Ayres-Peres & Mantelatto, 2010;Pereira et al, 2009) and Japanese coasts (Oba et al, 2008). As this taxon does not affect shell weight (Ayres-Peres & Mantelatto, 2010), it may be advantageous for the crab to inhabit a shell with bryozoans.…”

“…As this taxon does not affect shell weight (Ayres-Peres & Mantelatto, 2010), it may be advantageous for the crab to inhabit a shell with bryozoans. In addition, bryozoans belonged to the category of "improvers" of the shell structure, because they produce calcareous colonies that can modify the morphology of the shells greatly, granting greater protection to the hermit against predators through the increased resistance of the shells or even providing camouflage (Ayres-Peres & Mantelatto, 2010). Therefore, although no species is an obligate symbiont, the high incidence of bryozoans on hermit crabs suggests a beneficial relationship between them in non-consolidated environments and, consequently, this association favors a cooperative relationship, which is an act performed by an individual that increases the fitness of another (Bergmüller et al, 2007) Another pattern found was the constant presence of epibionts in larger animals, which could be age and molting frequency-related (Davis & White, 1994).…”

“…In the southern region of Brazil, there is still a gap in studies concerning the occurrence and characterization of epibionts associated with gastropod shells occupied by hermit crabs. Ayres-Peres and Mantelatto (2010) analyzed the occurrence of epibionts in shells used by the hermit Loxopagurus loxochelis Moreira, 1901 in the coast northeast of the state of São Paulo; Turra (2003) and Turra et al (2005) investigated the inlaying of epibionts and the adequacy of shells used by sympatric hermit crabs of the genus Clibanarius Dana, 1852 on the island of Pernambuco, Brazil;and Sant'Anna et al (2004) studied a symbiosis in Clibanarius vittatus (Bosc, 1802) in São Vicente, São Paulo, Brazil. In this study, we used the hermit crab Isocheles sawayai Forest & Saint Laurent, 1967, on the northern coast of Santa Catarina, Brazil, to characterize the epibionts found in the shells and to evaluate different internal and external infestation types among males, females, and ovigerous females and among different sizes of animals.…”

Shell occupation and ectosymbionts of two hermit crab species in the South Atlantic: a comparative analysis

“…In hermit crabs, these organisms are mainly associated on the surface of occupied gastropod shells. The few studies on the occurrence of ectosymbiont organisms on shells occupied by hermit crabs include those of Turra & Leite (2001) and Turra (2003), who investigated the ectosymbionts and adequacy of shells used by sympatric hermit crabs of the genus Clibanarius Dana, 1852 on the Island of Pernambuco, São Sebastião, São Paulo; and Ayres-Peres & Mantelatto (2010), who analysed the occurrence of ectosymbionts on shells used by Loxopagurus loxochelis Moreira, 1901 in two areas of the north-east coast of São Paulo. These studies were restricted to the southern region of Brazil.…”

“…Where this identification was not possible, ectosymbionts were classified in greater taxonomic groups and their frequency of occurrence was evaluated. We used a qualitative classification adopted from Ayres-Peres & Mantelatto (2010), which consisted of recording the presence or absence, and when possible, the position of these organisms on the surface of the shell. Most of the surfaces were completely covered, so it was not possible to describe the exact boundaries of many fouling organisms.…”