Gastropod shell utilisation pattern by the hermit crabClibanarius symmetricus(Anomura: Diogenidae) in an Equatorial Amazon estuary

Abstract

Clibanarius symmetricus is a diogenid hermit crab that is highly abundant in rocky intertidal environments, including the rock outcrops of Amazon estuaries. This study characterises the C. symmetricus shell utilisation pattern in the Marapanim River estuary, Pará, Equatorial Amazon, based on the hypothesis that occupancy patterns would differ, in relation to biometry and diversity of occupied shells, from those of other regions in the range of this species due to the distinct and unique environmental characteristics of equatorial estuaries. Monthly samplings were carried out from August 2006 to July 2007, in the upper and lower areas of the mid-littoral during low tides. A total of seven gastropod species were found as shells occupied by hermit crabs: 93.33% were Thaisella trinitatensis shells, 2.00% Nassarius vibex, 2.00% Neritina virginea, 1.33% Natica marochiensis, 0.67% Parvanachis obesa, and, occasionally, Littorina flava and Phalium granulatum shells, each with only one occurrence (0.33%). Juveniles [cephalothoracic shield length (CL) of less than 3.6 mm] occupied a higher variety of shells, while adults occupied shells with larger meristic variation. Males occupied larger shells. The length of the animal was influenced by shell measurements (total width, aperture width and weight). Clibanarius symmetricus showed occupancy patterns generally similar to those of specimens of the same species previously studied in the Brazilian subtropical region, and this occupancy is explained by shell availability, shell size and weight, and hermit size. However, this study showed lower occupied shell species diversity, and the species with highest occupancy frequency (T. trinitatensis) was not reported in any previous studies on this hermit crab. In addition, the studied population differed in occupancy patterns, with differences between males and females, and between juveniles and adults.

Never forget where you came from: Microhabitat of origin influences boldness and exploration in the hermit crab Clibanarius symmetricus (Diogenidae)

“…Therefore, this behavioral trait can have important implications for resource acquisition in a competitive context and appears to not be affected by predation risk. In C. symmetricus, bolder individuals can benefit from obtaining large shells, which are often a limited resource (Rodrigues and Martinelli-Lemos, 2016). Shell size has significant impacts on individuals' growth capacity, which can affect male fertility and female fecundity (Osorno et al, 1998).…”

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

“…In addition to providing protection, rocky substrates provide a wider variety of microhabitats, in which many organisms that provide nutritional resources can be found (Fransozo et al, 2008). The rocky outcrops of the estuaries of the Amazon coast harbor a wealth of decapod crustaceans (Oliveira et al, 2012;Silva and Martinelli-Lemos, 2012;Oliveira et al, 2013;Morais and Lee, 2014;Sampaio and Martinelli-Lemos, 2014;Rodrigues and Martinelli-Lemos, 2016;Nóbrega and Martinelli-Lemos, 2016), which may create an environment favorable for the development of hermit crabs.…”

“…The availability of gastropod shells and competition for this resource are also important factors influencing the distribution of hermit crab populations (Hazlett, 1981;Martinelli and Mantelatto, 1999;Bertini and Fransozo, 2000;Fransozo et al, 2008), including C. symmetricus (Sant' Anna et al, 2006b;Rodrigues and Martinelli-Lemos, 2016). Variation in the availability of food sources and the feeding behavior of the crabs may also have an important influence on the large-scale distribution of C. symmetricus (Dunbar et al, 2003).…”