When These Snakes Play Dead, Soiling Themselves Is Part of the Act

Most snakes flee or fight when attacked. Then there are the dice snakes of Golem Grad, an island on a lake in North Macedonia. Grabbed by a predator, they writhe theatrically, soiling themselves with a pungent cocktail of musk and feces. Eventually they go limp, mouth gaping, tongue protruding. To really sell the part of playing dead, some even bleed from their mouths.

Just as buckets of stage blood can help sell an unconvincing fight onstage or onscreen, the snakes’ use of disgusting fluids may be the key to putting on a convincing death performance, according to research published Wednesday in the journal Biology Letters.

Various species across the animal kingdom feign death when bothered by a predator, including insects, fish and amphibians. Even mammals do it — the most famous of which has lent its name to the technique: “playing possum.”

Such a performance can be a “high risk, high reward scenario,” said Vukasin Bjelica, a doctoral student at the University of Belgrade and an author on the study. Some predators are confused — or disgusted — by animals that abruptly go limp, especially while those animals are stinking and bleeding. Others may stop paying close attention and loosen their hold, giving prey time to escape. But it requires the performer to lie unmoving around an animal that is interested in eating it. The prey therefore has a strong incentive to try to lessen the amount of time spent playing dead.

Mr. Bjelica’s research is focused on dice snakes, a nonvenomous, fish-loving species found from Western Europe all the way to western China. The species as a whole has a variety of defensive techniques, including biting, puffing up and flattening their heads to look like a venomous snake. But the snakes of Golem Grad island — whose main predators are birds — often play dead.