Meeting Abstract
Snapping shrimp (Decapoda: Alpheidae) are a family of crustaceans that have evolved a unique snapping claw that produces cavitation. Snapping shrimp with the most powerful snapping claws have evolved a form of specialized armor, the orbital hood, that covers their head and eyes. The presence of the orbital hood, along with the intriguing behavioral ecology of some species, has led to the hypothesis that snapping shrimp are blind. Here, we explore this hypothesis by examining the morphology, physiology, and behavior associated with the visual system of the big claw snapping shrimp, Alpheus heterochaelis. We find that A. heterochaelis, a snapping shrimp with a powerful snapping claw, has an orbital hood that covers the eyes completely and transmits 90% of incident light. The well-developed reflecting superposition compound eyes of A. heterochaelis are physiologically functional when tested using electroretinography (ERG) and microspectrophotometry (MSP). ERG indicates that snapping shrimp have a maximum spectral sensitivity near 500nm and demonstrate a flicker fusion frequency of 25-34hz. MSP shows that the visual pigments of A. heterochaelis are maximally sensitive to light at 501nm. Optomotor assays suggest that snapping shrimp can perceive and behaviorally respond to spatial cues. These results indicate that snapping shrimp are capable of detecting and responding to visual signals despite the presence of their orbital hood. In the future, we will study the co-evolution of weaponry, armor, and visual systems across Family Alpheidae.
