Mechanistic origins of bombardier beetle (Brachinini) explosion-induced defensive spray pulsation

Abstract

A beetle's internal bomb Bombardier beetles shoot a toxic pulse at potential predators and other harassers. The toxic spray is created by a chemical reaction that occurs inside the beetle's body. Although the details of the reaction are known, how the beetle is able to precisely combine the chemicals at appropriate times and release the pulse at regular intervals has remained a mystery. Arndt et al. used synchrotron x-ray imagery to observe the process as it occurs within live beetles. Expansion and contraction of an internal expansion membrane facilitate the precise cyclic injection of reactants and the subsequent ejection of toxic sprays that keep the beetle's predators at bay. Science , this issue p. 563