2013 Volume 68 Pages 37-41
The feeding behavior of the leucosiid crab Pyrhila pisum was observed, and its diet composition was analyzed, on a sandy tidal flat of Hakata Bay, Fukuoka, Japan during the day from May to September in 2011 and 2012. Pyrhila pisum were seen mostly wandering, resting, or engaging in mating behavior; only a few crabs exhibited feeding behavior. The crabs were carnivorous, eating various small organisms including bivalves, snails, hermit crabs, brachyuran crabs, isopods, amphipods, flatworms, and fish, but their diet was highly biased to bivalves, especially Arcuatula senhousia and Venerupis philippinarum. In addition, diet preferences differed annually: A. senhousia predominated as prey through the 2011 survey, but in 2012 V. philippinarum predominated in the early season while A. senhousia became the dominant prey later. Pyrhila pisum usually ate small, thin-shelled shallowly buried living animals, but large, dead V. philippinarum occurred abundantly in the early season of 2012, and P. pisum could easily consume their soft tissues. In contrast, P. pisum did not actively capture benthic animals such as hermit crabs, snails, or varunid crabs, which were abundantly on the tidal flat, and showed no interest in jellyfish, green algae, or vascular plant detritus for both male and female crabs. The preference for bivalves was similar, but males tended to eat more snails (Batillaria sp. and Nassarius festivus) than females did, probably because their larger chelipeds better allowed them to handle snails. In sum, P. pisum is a predator of small and slow-moving benthic animals distributed on or just under the substrate's surface and a scavenger biased to preying on bivalves.
