Y: Don, if a hungry lion grabbed you by the leg, would you tear it off to escape?
D: Ew! What kind of question is that Yaël?
Y: For most animals the natural world is a rough place. The danger of being eaten by predators is always present. Some animals can detach a tail or a limb along a point of weakness to escape the grasp of a predator. The phenomenon is called autotomy, and scorpions are a good example.
D: But, can't scorpions defend themselves with their venomous sting?
Y: Apparently not always. In 2015 an international team of biologists reported discovering that when tropical scorpions are grasped by the tail, they break it off and escape.
D: The tail is an important part of a scorpion's anatomy. It contains the sting that it uses to subdue prey and defend itself from predators. Even more importantly, it contains the -- um, anus, without which the scorpion can't poop. How could it possibly live without it?
Y: The researchers found that the tail scar quickly sealed against fluid loss. Without a sting, scorpions couldn't capture large prey, but they could still catch and devour small crickets well enough to live on for at least eight months. Scorpions don't produce much bodily waste, but what they did produce accumulated in a swollen mass at the end of the animal's tail stump. They sometimes rid themselves of this load by losing another tail segment.
D: Yuck! Does the ability to lose their tail really benefit scorpions?
Y: It does, because afterwards, they can still mate and pass on their genes. If they had been eaten by the predator, they couldn't. That makes autotomy an evolutionarily adaptive trait.