When animals come into contact with a predator, they may lie completely still or “play dead” as a last resort to survive. But what happens after that? Scientifically known as post-contact immobility, the behavior some animals adopt is rear Feigning death appears to be highly individual and random. The small insect study was published Aug. 22 in the journal ProSone It turns out that it’s virtually impossible to predict how long they’ll pretend to be dead, or what they’ll do once they feel the danger has passed, and they may respond differently depending on the situation.
Why animals pretend to be dead
Some animals stay still to make predators think they’re a rotting corpse that’s too dangerous to eat, and some snakes secrete blood and feces to make their corpse appear even more decayed and unappetizing. opossum Sharks are probably the animals best known for deploying this tactic, but it has also been observed in other species. Go bankrupt When a predator approaches, Poultry, Other.
[Related: These snakes play dead, bleed, and poop to avoid being eaten.]
In this new study, Anteater Larvae (Euroleon Nostras) are a group of over 2,000 species of tiny, hairy insects known for burrowing and eating ants. Insects tend to seek safety by burrowing into the material in which they live. 2021 Survey The same team’s experiments with antlion larvae revealed that the insects would become completely motionless when scientists handled them individually and then weighed them. These tiny bugs move around on the pan of the scale, so it can be really hard to get an accurate measurement. But the team found that antlion larvae It didn’t move at all. That’s more than enough time to support their weight.
Context matters
Building on that work, the team looked at how antlion spiders react to animals they perceive as predators. Automatic Video Tracking Intermittent movement of insects Substrate– or various Layers of sand, soil, or other materials It’s where they live.
The researchers found that the antlion’s behavior after playing dead depended on what escape route was available to it, such as digging a deeper hole or hiding in the top layer. The awakening and escape behavior was highly individual and unpredictable, with one antlion remaining completely motionless for over an hour.
“We chose to investigate so-called ‘playing dead’ behaviour and found that the length of time that any individual antlion remains motionless is completely unpredictable,” says study co-author Nigel Franks, an evolutionary biologist and professor emeritus at the University of Bristol in the UK. It said in a statement.
The post-contact resting states were completely random, but widely predictable across insects, similar to the behavior of radioactive atoms.
“Like radioactive atoms, the times when each individual state will change are unpredictable, but the patterns in the population are entirely predictable,” Franks said.
[Related: Female frogs appear to play dead to avoid mating.]
The team pretended it was dead. Adaptation ActionsThis unpredictable behavior means predators don’t know how long to wait before their prey becomes mobile again and more visible. Adapted abilities Antlion traps don’t move around until they feel safe, but it’s possible that a predator carrying a antlion could drop it onto hard surfaces, like concrete, where the antlion can’t easily burrow. More research is needed to test this scenario.
“Our study may be the first to determine what animals do after they play dead, and it shows that their behavior depends on the situation. It’s a trade-off,” Franks said. “Our study therefore opens up the field to study the afterlife of a great many animals that exhibit playing dead, postmortem, or what we call post-contact immobility.”
