Shell preference in a hermit crab: comparison between a matrix of paired comparisons and a multiple-alternative experiment

Abstract

The preference of the hermit crab, Calcinus californiensis, among six species of shells, was tested by two diVerent experiments. The Wrst experiment used pair-wise trials, analyzing the preference by Chi-square tests using two diVerent constructions of the null hypothesis. One hypothesis was based on a no-preference among shell species, the second on comparing the number of crabs changing for a particular shell species when two options were given versus the changing when no options were oVered. The second experiment was a multiple-alternative test based on a rank ordering of the shell preference. This method has both statistical and resource-saving advantages over the traditional pair-wise comparisons. The sequence of shell preference was similarly independent of the procedure used. The preferred shell species are heavy and might be associated with hydrodynamic advantages and with the protection against predation. The shell preference matches with the pattern of shell occupancy indicating that the shell use in nature is determined by the crab's preference. The information generated may be used for further research on shell preference as a methodological alternative.

Prevalence, reproduction and morphology of the parasitic isopodAthelges takanoshimensisIshii, 1914 (Isopoda: Bopyridae) from Hong Kong hermit crabs

“…Scully 1979; but see Peura et al 2013). The factors that influence shell choice by hermit crabs have been extensively studied (see Arce & Alcaraz 2012;Peura et al 2013;Wooi & Ching 2013) and it is has been documented that they will utilize suboptimal shells (e.g. too heavy, not large enough, or easily cracked) if others not are available.…”

Mismatch between body growth and shell preference in hermit crabs is explained by protection from predators

“…IV/M = 0.50 ± 0.03; n = 11), and N. scabricosta (IV/M = 0.69 ± 0.04; n = 11; Arce & Alcaraz, 2012). These four species will be further referred by their generic names.…”

“…Shells of Mancinella are more preferred by C. californiensis than Columbella and Nerita and less preferred than Cantharus and Stramonita (Arce & Alcaraz, 2012). The hermit crabs were taken to the laboratory and acclimatized in their own shells to controlled conditions (28°C, salinity of 35, aeration, and 12 h light: 12 h dark) for 4 weeks.…”

“…Each hermit crab was provided with six empty shells ranging around the adequate size (±10% shell weight). The adequate shell size for each individual was estimated using the appropriate regressions between shell size and body size for this hermit crab species (Arce & Alcaraz, 2012). The crabs were allowed to choose within these shells for 24 h and after this time all the empty shells were removed.…”

“…However, the sequence of shell preference of the intertidal hermit crab Calcinus californiensis (Bouvier, 1898) shows that this crab prefers relatively heavier shell species (having a low IV/M ratios), like Cantharus sanguinolentus and Stramonita biserialis, over relatively lighter shells (high IV/M ratios), such as Nerita scabricosta and Columbella sp. (Arce & Alcaraz, 2012). However, with few exceptions, such as the case of C. compressus (Contreras-Garduño et al, 2009), the association between body growth and shell preference in hermit crabs has not been previously investigated.…”