Population structure and growth of the hermit crab Diogenes pugilator (Decapoda: Anomura: Diogenidae) from the northeastern Atlantic

A population of the hermit crab Diogenes pugilator from the northeastern Atlantic (Barbate, Straits of Gilbraltar, Spain) was studied. The results show continuous recruitment throughout the year, within a size range from 0.4-1.02 mm in cephalothoracic shield length, as a consequence of the prevalence of ovigerous females throughout the year. The sex ratio was in favor of females. Results of size-frequency distributions from different locations show that there was no clear segregation of sizes by sexes or depths. Five cohorts can coexist, although a decrease in the number of specimens was observed in the second year studied, perhaps induced by human influences in the area (the building of a new harbor and the restoration of the beach). The values of the Von Bertalanffy parameters (K and L infinity) showed slight differences between sexes and between years within sexes, as is shown in the phi' index analysis. The estimated maximum longevity of the individuals in the population studied was about 2 years, but normally the cohorts lived in the study area for approximately 1 year.