Strike mechanics of an ambush predator: the spearing mantis shrimp

Full Citation: 

deVries, M.S., E. A. K. Murphy, S. N. Patek. 2012. Sit-and-wait predation: behavior and biomechanics of the "spearing" mantis shrimp. Journal of Experimental Biology 215 (24): 4374-4384.

Publication Year: 
2012
Publishing Journal Info: 

Journal of Experimental Biology

Ambush predation is characterized by an animal scanning the environment from a concealed position and then rapidly executing
a surprise attack. Mantis shrimp (Stomatopoda) consist of both ambush predators (ʻspearersʼ) and foragers (ʻsmashersʼ).
Spearers hide in sandy burrows and capture evasive prey, whereas smashers search for prey away from their burrows and
typically hammer hard-shelled, sedentary prey. Here, we examined the kinematics, morphology and field behavior of spearing
mantis shrimp and compared them with previously studied smashers. Using two species with dramatically different adult sizes,
we found that strikes produced by the diminutive species, Alachosquilla vicina, were faster (mean peak speed 5.72±0.91ms−1;
mean duration 3.26±0.41ms) than the strikes produced by the large species, Lysiosquillina maculata (mean peak speed
2.30±0.85ms−1; mean duration 24.98±9.68ms). Micro-computed tomography and dissections showed that both species have the
spring and latch structures that are used in other species for producing a spring-loaded strike; however, kinematic analyses
indicated that only A. vicina consistently engages the elastic mechanism. In the field, L. maculata ambushed evasive prey
primarily at night while hidden in burrows, striking with both long and short durations compared with laboratory videos. We
expected ambush predators to strike with very high speeds, yet instead we found that these spearing mantis shrimp struck more
slowly and with longer durations than smashers. Nonetheless, the strikes of spearers occurred at similar speeds and durations to
those of other aquatic predators of evasive prey. Although counterintuitive, these findings suggest that ambush predators do not
actually need to produce extremely high speeds, and that the very fastest predators are using speed to achieve other mechanical
feats, such as producing large impact forces.

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