Abstract
Interspecific interactions between two species of grass shrimps, Latreutes acicularis and Heptacarpus geniculatus living on Zostera marina leaves, were studied in aquaria. These species compete for space on Zostera leaves as a refuge. In encountering between individuals of two species, crawling retreat or jumping avoidance was observed frequently. Latreutes acicularis was inferior species at the encountering than H, geniculatus. Even without refuges, a predatory fish, Hypodytes rubripinnis, prefers L. acicularis as a food. However, when housed with the predator, encountering among individuals of shrimps reduced significantly by inactive behaviors of both species. The competitive interactions for refuges between two species of shrimps, are remarkably depressed under existence of predators, and thus coexistence of these species could be sustained.
