Female Frogs Fake Death to Avoid Sex

Female frogs, specifically the European common frog, deploy a number of strategies to ward off hyper-amorous males, including faking their own deaths. Researchers from the Museum für Naturkunde in Berlin published the sex-averse findings in the journal Royal Society Open Science.

European common frogs (Rana temporaria) engage in “explosive breeding,” a brief sex frenzy in early spring lasting from a few days to two weeks. In the orgy pond males outnumber females by a large margin so competition is fierce. “The males are not choosy and will cling to anything that moves with great vigor,” according to the museum’s press release. If a male is mistakenly mounted, he’ll give a “release-call” to indicate the sexual misfire.

In the free-for-all bacchanalia it often happens that many males will cling to a single female in a “mating ball,” which can kill the poor girl. To avoid this unhappy fate, she will sometimes imitate the male release-call in a deep, low-frequency grunt. (The males, we hasten to add, are not very bright.) Her most common survival strategy is to flip over, which dunks the male underwater so that he must let go or drown.

When all else fails, the females will commence what the researchers call the “final and most astonishing behavior” of tonic immobility, commonly known as faking death. Here the ladies stiffly extend arms and legs away from their bodies and remain immobile until the male releases them. Given the nonstop battle of the sexes during sex, it is astonishing that this species manages to reproduce at all.

Relatedly, the females of some spider species also fake death during sex, but for a very different reason: to lull the male into the false sense of security that he won’t be eaten when his task is completed. We have much to learn from the animal kingdom.