To evade becoming prey, certain creatures simply feign death until they succeed. And simulated demises featuring numerous unappealing elements may enhance the entire act's efficiency, as per a study published May 8 in Biology Letters.
Dice snakes that hemorrhage from the mouth and coat themselves in musk and excrement
spend less time simulating death compared to those that abstain from such tactics, researchers reveal. These defenses, the scholars propose, might work synergistically, amplifying the overall impact of the display while hastening the snake's escape from a predator.
Pretending to be dead is
a widespread defensive strategy across the animal realm. It often entails prey remaining motionless while exposing vulnerable body parts, making it a high-risk yet potentially high-reward maneuver. Many predators refrain from attacking seemingly lifeless entities, possibly due to parasites or because the absence of movement fails to provoke their predatory instincts.
The dice snake (Natrix tessellata) employs particularly elaborate theatrics when staging its demise. When caught, it thrashes about and emits a hiss before dousing itself — and likely the predator — in excrement and musk. As a grand finale, it widens its mouth, protrudes its tongue, and fills its oral cavity with blood.
Biologists Vukašin Bjelica and Ana Golubović from the University of Belgrade in Serbia sought to determine if these combined defensive tactics expedite the entire ruse. They captured 263 wild dice snakes on the island of Golem Grad in North Macedonia and noted any instances of excrement or musk smearing. The team then placed the snakes on the ground and retreated from view, mimicking the behavior of a hesitant predator, before documenting all subsequent actions.
Just under half of the snakes smeared themselves in musk and excrement, while approximately 10 percent bled from the mouth. Some simulated deaths devoid of musk, feces, or blood lasted nearly 40 seconds. The 11 snakes employing all three defenses collectively spent, on average, roughly two seconds less feigning death.
Perhaps the combination of these three strategies intensifies the spectacle for the predator, curbing their interaction with the animals and bolstering the snake's survival prospects. "Two seconds might not seem significant but could provide ample time for a snake to flee if the predator refrains from attacking," remarks Bjelica. "Even a slight chance can determine whether it gets consumed or not."
In the past decade, asserts evolutionary ecologist Tom Sherratt of Carleton University in Ottawa, "there has been a trend to view antipredator responses not in isolation but as a unified whole." These recent findings, he contends, prompt inquiries: "What accounts for the variation? Why don't they all exhibit auto hemorrhaging and fecal display? It could be related to their experiences, but there's variability requiring explanation."
Ecologist Katja Rönkä of the University of Helsinki posits that the next phase involves scrutinizing the predator's perspective on this behavior: "What dissuades them from attacking 'lifeless' animals, especially after witnessing them alive?"
