Ecological information of land hermit crabs (Crustacea: Decapoda: Anomura: Coenobitidae) and new record in Dongsha Atoll National Park, Taiwan

Ecological information of land hermit crabs (Crustacea: Decapoda: Anomura: Coenobitidae) and new record in Dongsha Atoll National Park, Taiwan

Land hermit crabs play an important role in island ecosystems. They are seed dispersers and debris scavengers in coastal forests to accelerate the decomposition of organic substances. Since the establishment of Dongsha Atoll National Park, Dongsha Island, Taiwan in 2007, researchers have been able to reach the atolls easily and conduct ecological surveys of land hermit crabs. In the current survey conducted from 2013 to 2018 on Dongsha Island, we recorded six land hermit crab species: Birgus latro, Coenobita rugosus, C. brevimanus, C. violascens, C. cavipes, and C. purpureus. Of these, C. cavipes and C. purpureus were newly recorded on Dongsha Island. C. rugosus was the dominant species, with a much larger population than those of other the species. C. rugosus demonstrated no sex ratio bias; however, C. rugosus males were considerably larger than C. rugosus females. Approximately 80% of C. rugosus used the shells of Achatina spp. and demonstrated the presence of three cohorts. We also provide the body size and weight for condition index of C. rugosus. Surprisingly, three individuals of C. purpureus, the species endemic to Japan, were also recorded. Overall, our study revealed the current situation of land hermit crabs on Dongsha Island.