Science

Faking death to fool predators like ‘a conjuring trick' – study

Scientists observed an insect that played dead for 61 minutes, saying the process is kept long but unpredictable.

Animals have long been observed faking death in a desperate attempt to avoid predators but scientists say the length of time is kept long but unpredictable.

This tense strategy creates a deadly game of hide and seek, as the grumbling stomachs of predators cannot afford to wait around forever, and their prey also need to get on with their lives at some point.

Charles Darwin recorded a beetle that kept completely still for 23 minutes, but the University of Bristol has observed an antlion larvae insect that pretended to be dead for as long as 61 minutes.

The study, published in the Biology Letters journal, analysed the benefits of death-feigning when a predator eyes up small populations of conspicuous prey.

Lead author Professor Nigel R Franks said the move is like “a conjuring trick”.

“Imagine you are in a garden full of identical soft fruit bushes. You go to the first bush,” he explained.

“Initially collecting and consuming fruit is fast and easy, but as you strip the bush, finding more fruit gets harder and harder and more time-consuming.

“At some stage, you should decide to go to another bush and begin again. You are greedy and you want to eat as many fruit as quickly as possible. The marginal value theorem would tell you how long to spend at each bush given that time will also be lost moving to the next bush.

“We use this approach to consider a small bird visiting patches of conspicuous antlion pits and show that antlion larvae that waste some of the predator’s time, by ‘playing dead’ if they are dropped, change the game significantly. In a sense, they encourage the predator to search elsewhere.

“Thus, playing dead is rather like a conjuring trick. Magicians distract an audience from seeing their sleights of hand by encouraging them to look elsewhere.

“Just so with the antlion larvae playing dead – the predator looks elsewhere. Playing dead seems to be a very good way to stay alive.”

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