Occurrence and distribution of early juvenile land hermit crabs at a small beach on the Boso Peninsula, Japan

Abstract

The present study was conducted to examine the occurrence and distribution of early juvenile land hermit crabs of the genus Coenobita on a small beach on the Boso Peninsula, Japan as a basis for understanding the important habitats that land hermit crabs use during the sea-to-land transition. The survey sites were supratidal zones at six points with heterogeneous topography, and visual surveys for early juveniles were conducted from middle July to late October in 2015 and 2016. The number of empty gastropod shells in four quadrats along the intertidal zone at each point was also counted in the 2016 survey. The occurrence of early juveniles varied among survey points and was spatially stable for two successive years. The first appearance and abundance of early juveniles varied among survey years. Early juveniles were abundant at points with a gravel bottom throughout the intertidal zone, and empty gastropod shells were also abundant at these points. The abundance of early juveniles was highly correlated with the amount of empty gastropod shells. Thus, our surveys suggested the importance of the sediment types and abundance of empty gastropod shells in the intertidal zones for settlement and landing by land hermit crabs.

Effect of salinity on survival and emigration behaviour during the sea-to-land transition of three terrestrial hermit crab species (Decapoda: Anomura: Coenobitidae) under laboratory conditions

“…Early juveniles of C. purpureus inhabit sandy beach conditions (Hamasaki et al, 2018;Sanda et al, 2018aSanda et al, , 2018bInutsuka et al, 2020) with high ground temperatures (Hamasaki et al, 2018) that may induce overheating and desiccation, thereby leading to hypersaline environments. Megalopae and early juveniles of C. purpureus might have evolved the strong hypo-osmoregulatory ability to adapt to the high-temperature niche.…”