Acorn-foraging activity and feeding behaviour by two species of freshwater crabs (Brachyura: Potamidae) from Okinawa Island, Ryukyu Islands, Japan

Research reveals that two species of freshwater crabs, Geothelphusa grandiovata and Candidiopotamon okinawense, play an unintended role in the dispersal of acorns from Castanopsis sieboldii and Quercus miyagii in the Yanbaru forest on Okinawa Island. These crabs forage for acorns near streams, storing them in burrows where some germinate, thereby aiding seed dispersal in areas where natural lodging is difficult. Laboratory feeding experiments confirmed that the crab G. grandiovata leaves characteristic feeding scars on acorns, matching those found around their burrows. This behavior suggests a symbiotic relationship between the crabs and these tree species, facilitating forest regeneration along valley slopes.

Sasaki, T., & Naruse, T. (2014). Acorn-foraging activity and feeding behaviour by two species of freshwater crabs (Brachyura: Potamidae) from Okinawa Island, Ryukyu Islands, Japan. Crustacean Research, 43(0), 31–40. https://doi.org/10.18353/crustacea.43.0_31