Study on Shell Utilization Pattern of Two Sympatric Hermit Crab Species on the Rocky Intertidal Region of Veraval, Gujarat, India

Abstract

The present study illustrates the shell utilization and resource partitioning of two sympatric hermit crab species Clibanarius rhabdodactylus and Clibanarius ransoni with reference to gastropod shell species (shell shape), shell size and shell availability. Specimens were collected from January to March 2021 and hermit crab weight and shield length were measured. The gender of occupant hermit crab was identified and categorised into male, non-ovigerous female and ovigerous female. Gastropod shells were identified and different morphological parameters like shell length, shell aperture length and width, shell volume and dry weight were measured. The population of C. rhabdodactylus and C. ransoni was female biased with male: female ratio being 1:1.93 and 1:1.25 respectively. Clibanarius rhabdodactylus and C. ransoni were occupying 29 species and 28 species of gastropod shells respectively among which > 75% occupied shells were comprised of Cerithium caeruleum, Lunella coronata, Turbo bruneus, Tenguella granulate and Pollia undosa. Both the Clibanarius species were showing a high overlap in their intertidal distribution as well as gastropod shell use pattern. Cerithium caeruleum was found to occur in high abundance as compared to other gastropod species in the study area which may also influence the shell utilization of hermit crab species. Males and non-ovigerous females of the hermit crab species utilized almost all shell species, while ovigerous females used only a few shell species. Significant relationship was observed between different morphological parameters of the occupant crab species and occupied shells. Shell partitioning was evident between hermit crab sexes as well as reproductive stages on the basis of occupied shells of different species, shapes, and sizes. The present study revealed shell occupation pattern of C. rhabdodactylus and C. ransoni is highly influenced by the diversity, morphology and availability of gastropod shells in the study area.