When attacked, some scorpions discard their stinger—and their anus

Mattoni et al., 2015

When attacked, some scorpions discard their stinger—and their anus

Any kid knows that if you grab a lizard by its tail, it can snap off the tip and run away. Now it turns out some scorpions can pull the same stunt, sacrificing not only their stingers but also their ability to poop. Researchers have discovered 14 species of Ananteris scorpions in the northern jungles of South America that break off their tails to avoid capture. The discarded stingers writhe and wriggle on the ground, possibly to distract predators as the owner makes its escape. Back in the lab, researchers grabbed scorpions’ stingers with forceps and found that the armored arachnids actively tore off their own tails when they felt the pinch (see video). Surviving scorpions’ stumps healed within days, researchers found, but their tails, which contain the anus and part of the digestive system, did not grow back. Tailless scorpions survived up to 8 months in the lab, but their abdomens swelled with trapped excrement within weeks. At least one lost a second segment of tail to the internal pressure. In the wild and in the lab, male scorpions were much more likely than females to snap off their tails, the team reports this week in PLOS ONE. The results raise questions about the evolutionary trade-offs faced by the two sexes. Without their stingers, males could still hunt small prey and mate successfully, the researchers found, suggesting that 8 more months of life could be worth the world’s worst case of constipation.