Notes on growth-patterns and shell-utilization of the hermit crabPagurus bernhardus(L.)

Abstract

Studies made of specimens of Pagurus bernhardus kept for six months in shells of different sizes showed that they grew appreciably faster in shells which were large relative to their body size than they did in shells which were too small. This difference was especially marked in the increase per molt but less so in the number of days per molt. A new standard of measurement, the length of the front (hard) portion of the carapace, is proposed for these crabs. The reasons for this choice and a conversion factor between the new standard and that frequently used, the whole carapace, are presented. A formula relating size to instar number is derived for this species, but the molt frequency was too variable to permit a determination of an age-size relationship. Finally, observations were made on the weight-to-volume ratios of some of the gastropod shells inhabited by this species in the Øresund and on the ratios of the weights and volumes of the shells to the crabs which bear them.