Observation of air-exposure behaviour in the reef hermit crab, Calcinus elegans (H. Milne Edwards, 1836) (Decapoda, Diogenidae)

Abstract

Abstract Many species of hermit crabs, such as Calcinus and Clibanarius spp., live on the rocky shores of tropical and warm temperate regions. During low tides, some of these species climb out of the tidal pools onto rock surfaces exposed to the air. In the genus Calcinus, however, such ‘Air-exposure (AE) behaviour’ was only known previously from Calcinus laevimanus. During a field study of the hermit crab fauna on Amami Oshima Island, Kagoshima, Japan, the AE behaviour of Calcinus elegans (Decapoda, Diogenidae) was observed on rocky shores. Moreover, the repeatability of the AE behaviour was confirmed. Therefore, we documented the AE behaviour of C. elegans as a second record of AE behaviour among Calcinus species by providing videographic evidence. The findings indicate that the AE behaviour has evolved in a broader range of Calcinus species than was previously assumed.