Distribution Patterns of Terrestrial Hermit Crabs and Enewetak Atoll, Marchall Islands

Habitat utilization, population structure, and activity were investigated for members of the family Coenobitidae on three islets at Enewetak Atoll, Marshall Islands. Small Coenobita perlatus ( < 8.0-mm carapace length) were more abundant in the beach habitat than medium-size (8-l9-mm carapace length)C. perlatus, C. rugosus, C. brevimanus, or Birgus latro. Large C. perlatus (2: 20-mm carapace length) were present on the beach only at night and engaged primarily in reproductive behavior. Coenobita rugosus on the beach at night were generally females which either had recently released their eggs and larvae into the lagoon or had eggs ready for hatching on their pleopods. The size at maturity was much smaller for the C. perlatus population on Bokandretok as compared with populations on Ikuren and Mut. The scarcity of medium-size individuals may result from a scarcity of suitable Turbo shells