ABOVE: The front set of legs of centipedes such as Scolopendra subspinipes have evolved into venom-injecting pincers.. 


The paper 
S. Yang et al., “Target switch of centipede toxins for antagonistic switch,” Sci Adv, 6:eabb5734, 2020.

While it’s handy to be able to neutralize prey or would-be predators with a bite or sting, being a venomous animal can be dangerous. Usually critters avoid the effects of their own venom “by keeping it in glands where it doesn’t go into the bloodstream and doesn’t affect them,” explains evolutionary biologist Kevin Arbuckle of Swansea University in the UK. But because accidents happen, it’s also advantageous to be able to survive exposure to one’s own toxic concoction—often by lacking the receptors the venom’s components bind to.

The centipede Scolopendra subspinipes both kills prey with its venom and uses it to temporarily stun conspecifics during fights for dominance. Ren Lai of the Kunming Institute of Zoology in China writes in an email to The Scientist that he and his colleagues wanted to understand why prey and conspecifics react differently.

In several of the centipede’s prey species, including mice, a venom component known as spooky toxin binds to potassium channels, including one called shaker, wreaking havoc on the nerves that control breathing and heartbeat. Lai’s team found the shaker channel in S. subspinipes cells carries a single amino acid change that protects the species from the worst effects of the venom. Injecting the centipedes with venom from other S. subspinipes, Lai and his colleagues confirmed that the arthropods were only temporarily immobilized; they recovered within 10 minutes. Cell culture experiments revealed that spooky toxin inhibited the shal channel, which affects both neurons and the vascular system and most likely explains the centipedes’ immobilization.

The experiments, says Arbuckle, who was not involved in the study, are “a really cool integration” of molecular-level work on venom and observations of the different purposes for which it’s used.