Animals feign death for long periods to escape predators

Many animals fake death to try to escape from their predators, with some individuals in prey species remaining immobile, if in danger, for long periods of time.

Charles Darwin recorded a beetle that remained idle for 23 minutes – however, the University of Bristol documented an individual antworm’s larva pretending to be dead for an astonishing 61 minutes. Equally important, the amount of time that an individual remains immobile is not only long, but unpredictable. This means that a predator will be unable to predict when a potential prey will move again, attract attention and become a meal.

Predators are hungry and cannot wait indefinitely. Likewise, prisoners may be missing out on opportunities to continue their lives if they remain immobile for a long time. Thus, the simulation of death can best be conceived as part of a deadly game of hide and seek, in which the prey can gain more by faking death if alternative victims are readily available.

The study, published today in the scientific journal Biology Letters, involved assessing the benefits of death simulation in terms of a predator visiting small populations of conspicuous prey. The researchers used computer simulations that use the marginal value theorem, a classic model in optimization.

The lead author of the article, Professor Nigel R. Franks, from the School of Biological Sciences at the University of Bristol, said: “Imagine that you are in a garden full of identical soft fruit bushes. You go to the first bush. Initially, collect and consuming fruit is quick and easy, but as you remove the bush, finding more fruit gets more and more difficult and takes longer.

“At some point, you must decide to go to another bush and start again. You are greedy and want to eat as much fruit as quickly as possible. The marginal value theorem would say how much time to spend on each bush given that time will also be lost moving to the next bush.

“We used this approach to consider a small bird visiting fragments of conspicuous anthill wells and to show that the antelion larvae that lose part of the predator’s time, ‘pretending to be dead’ if they are dropped, change the game significantly. , they encourage the predator to look elsewhere. “

The modeling suggests that the antlion’s larvae would not gain significantly if they remained immobile longer than they actually do. This suggests that, in this arms race between predators and prey, the death simulation has been prolonged to such an extent that it can hardly be improved.

Professor Franks added: “So, pretending to be dead is more like a magic trick. Magicians distract the audience from seeing their sleight of hand, encouraging them to look elsewhere. Likewise, with the larvae of antler pretending to be dead – the predator looks elsewhere. It seems that pretending to be dead is a good way to stay alive. ”