Visual acuity of the goby-associated shrimp, Alpheus rapax Fabricius, 1798 (Decapoda, Alpheidae)

Abstract

Species of alpheid shrimp that form symbiotic associations with gobiid fish are believed to possess poor visual capabilities. These shrimps are thought to heavily rely on their gobiid partners to detect threats and predators. The present study tested the visual capabilities of a goby-shrimp, Alpheus rapax Fabricius, 1798 to determine its visual reliance on the goby partner, Myersina macrostoma Herre, 1934. Alpheus rapax was found to possess the ability to perceive the colours green and blue, but not red. Although individuals tested did not respond to stationary figures, a statistically significant number of inviduals elicited a response when presented with a moving object. Results obtained from this study support the hypothesis that A. rapax does have limited visual acuity and is visually reliant on its goby partner while performing various activities outside its burrow.