Pattern of shell occupation by the hermit crab Pagurus exilis (Anomura, Paguridae) on the northern coast of São Paulo State, Brazil

Abstract

The purpose of this study was to determine the shell occupation pattern of Pagurus exilis using the percentage of shell types that were occupied and the morphometric relationship between hermits and occupied shells. Specimens were collected monthly from July 2001 to June 2003. A total of 1737 individuals were collected, occupying 19 gastropod shell species. Buccinanops gradatum (82%) was the most occupied shell, followed by Natica isabelleana (6.4%), Stramonita haemastoma (3.2%), and Cymatium parthenopeum (2.2%). There was a differential shell utilization pattern between sexes; males occupied larger and heavier shells while the non‐ovigerous females occupied the lightest ones. Pagurus exilis occupied more bare shells instead of incrusted ones. Buccinanops gradatum was the most occupied shell species as a function of its availability in the survey, and this occupation is strongly associated with the higher internal volume presented by these shells.

Keywords:

• Brazil
• hermit crab
• Pagurus
• shell occupation
• Southern Atlantic

Acknowledgements

This work is part of a bachelor thesis by M.T. and D.L.A.E. and was supported by Scientific Initiation Fellowships from FAPESP (Proc. 03/05408‐6) and PIBIC/CNPq, respectively. A.L.M. is grateful to FAPESP (Proc. 02/01646‐7) for a PhD on‐going fellowship; F.L.M. and R.B. are grateful to CNPq for Research (Proc. 301261/04‐0) and Post Doctoral (Proc. 150581/2003‐3) on‐going fellowships, respectively. Special thanks are due to Dr Adilson Fransozo for support and facilities during sampling collections provided by FAPESP—Biota Program (Proc. 98/07090‐3), to Dr Osmar Domaneschi (Zoology Department, IB, USP) for assistance with shell identification, to Dr Rafael Robles for his comments and suggestions on the manuscript, and to all NEBECC colleagues and to members of the Laboratory of Bioecology and Systematic of Crustaceans of FFCLRP/USP for their help during field and laboratory work. All experiments conducted in this study comply with current applicable state and federal laws.