The Animals that Turn Bodily Fluids Into Weapons
C ombat in nature is often a matter of tooth and claw, fang and talon. But some creatures have devised devious and dramatic ways to weaponize their bodily fluids, expelling them in powerful streams for the purposes of attack or self-defense.
Researcher Elio Challita became fascinated by fluid ejections in nature when he began studying an insect called the sharpshooter, which pees one droplet at a time using a method called superpropulsion. These insects consume 300 times their own body weight per day in xylem sap, a watery solution of minerals and other nutrients found in the roots, stems, and leaves of plants. To efficiently expel the resulting waste, they use a kind of internal catapult that helps overcome the surface tension in the droplets.
Challita and a team of researchers from the Bhamla Lab at Georgia Tech decided to survey the biomechanics and fluid dynamics that govern fluid ejections across the animal kingdom to see what commonalities they could find. Among others, they identified a number of creatures that use bodily fluids as powerful weapons in the fight for survival. These fluid ejections defy gravity and rebel against traditional notions of predator-prey tactics. The team’s review, “Fluid Ejections in Nature,” is forthcoming in the Annual Review of Chemical and Biological Engineering.
