Tuesday, August 7, 2007

PS 21-9: Hunting behavior in the spearing mantis shrimp, Lysiosquillina maculata

Maya deVries, University of California, Berkeley

Mantis shrimp are best known as aggressive foragers that smash hard-shelled prey, yet most mantis shrimp are actually sit-and-wait predators that spear soft-bodied, elusive prey from burrows constructed in soft substrates. My goal was to determine what factors affect the hunting behavior of a prevalent mangrove mantis shrimp, Lysiosquillina maculata, at Lizard Island, Australia. Based on the observation that areas with high wave action had less prey, I tested the hypothesis that L. maculata allocate more time to hunting when wave activity is high and prey is less available. I quantified hunting activity and prey abundance at two sites differing in wave action by counting prey and observing burrow activity twice a day for ten days. Burrows were coded as either open or closed, as open burrow entrances indicated that L. maculata were actively scanning for prey. Tidal height, time of day, and tide direction were also documented for each observation. A Chi-squared analysis and Fisher’s Exact Test revealed no significant differences between open and closed burrows for time of day and tidal height. However, there were significantly more open burrows than closed burrows at the site with high wave activity when the tide was rising (P<0.05). Prey abundance was also significantly lower at this site (P<0.05). These results suggest that L. maculata at Lizard Island allocate more time to hunting in areas with high wave activity and less available prey. This study offers new insights into the environmental context in which these formidable predators capture prey.