What Antlions Do After Playing Dead Revealed

A study led by scientists at the University of Bristol has unveiled what animals do after they pretend to be dead to avoid predators and the context of this behavior. Published in PLoS ONE, the research focuses on this death-feigning behavior, commonly known as "playing possum," which is also observed in humans under extreme conditions.

In their earlier work with antlion larvae, the researchers found that these insects become immobile when handled. This behavior is useful for weighing these tiny creatures accurately, as they remain still when gently placed on a balance.

Emeritus Professor Nigel Franks from the University of Bristol’s School of Biological Sciences led the study. He explained that the duration for which individual antlions stay motionless is highly unpredictable. This variability follows an exponential distribution, similar to the unpredictability of radioactive decay. However, the overall pattern across many antlions is consistent and predictable.

The study suggests that the antlion's ability to remain stationary for varying amounts of time likely helps them avoid detection. For example, an antlion might stay motionless for over an hour, making it difficult for a predator to gauge when the antlion will move again and become visible prey.

The researchers also explored what antlions do after pretending to be dead. They found that their actions are influenced by their surroundings. Antlion larvae, which typically burrow into the substrate to hide, may struggle if dropped onto a hard surface where they cannot escape. Using advanced automated video tracking, the researchers observed that antlions' responses after immobility depend on their escape options.

Professor Franks noted that this study is possibly the first to investigate the behavior of animals after they have "played dead." It highlights that these behaviors are context-dependent and introduces new opportunities for studying post-contact immobility in various species.