Shell availability and use by the hermit crab Clibanarius virescens along the Eastern Cape coast, South Africa

Abstract

Patterns of shell availability and use of the intertidal yellow-banded hermit crab Clibanarius virescens were studied by means of field sampling. Data were collected at three sites (Dwesa, Nqabara and Mendwana) along the Eastern Cape coast, South Africa. The most striking result was that at all three sites there was a difference between observed frequencies of shells used compared to that which was expected from their availability as live animals or empty shells on the rocks and the strandline. This suggests selection by the crabs. Crabs commonly used shells of Burnupena cincta and Burnupena pubescens and amongst other types, rarely used the shells of Cymatium dolarium and Stramonita capensis. Fewer types of shells were used than were available. A wider diversity of shell species were occupied at Dwesa (N = 11) and Nqabara (N = 10) than at Mendwana (N = 6). The diversity of shells used by the hermit crabs in this study falls within the globally predicted levels given body size of the study species and the latitude of the studied population.