"Strike mechanics of an ambush predator: the spearing mantis shrimp" will appear soon at the Journal of Experimental Biology. Authors Maya deVries (graduate student, Patek Lab), Elizabeth Murphy (former lab manager, Patek Lab) and Sheila Patek examine the kinematics and behavior of spearing mantis shrimp.
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 (“spearers”) and foragers (“smashers”). 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 examine the kinematics, morphology, and field behavior of spearing mantis shrimp and compare them to 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 to 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, spearers moved at similar speeds and durations to the strikes 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.