Pinching or stinging? Comparing prey capture among scorpions with contrasting morphologies

Abstract

Background: Scorpions can use their pincers and/or stingers to subdue and immobilize their prey. A scorpion can thus choose between strategies involving force or venom, or both, depending on what is required to subdue its prey. Scorpions vary greatly in the size and strength of their pincers, and in the efficacy of their venom. Whether this variability is driven by their defensive or prey incapacitation functionis unknown. In this study, we test if scorpion species with different pincer morphologies and venom efficacies use these weapons differently during prey subjugation. To that end, we observed Opisthacanthus elatus and Chactas sp. with large pincers and Centruroides edwardsii and Tityus sp. with slender pincers. Methods: The scorpion pinch force was measured, and behavioral experiments were performed with hard and soft prey (Blaptica dubia and Acheta domesticus). Stinger use, sting frequency and immobilization time were measured. Results: We found that scorpions with large pincers such as O. elatus produce more force and use the stinger less, mostly subjugating prey by crushing them with the pincers. In C. edwardsii and Tityus sp. we found they use their slender and relatively weak pincers for holding the prey, but seem to predominantly use the stinger to subjugate them. On the other hand, Chactas sp. uses both strategies although it has a high pinch force. Conclusions: Our results show that scorpionspecies with massive pincers and high pinch force as O. elatus use the stinger less for prey subjugation than scorpionspecies with slenderpincers.

Scorpion venom and its adaptive role against pathogens: a case study in Centruroides granosus Thorell, 1876 and Escherichia coli

“…Venom as an immune defense may provide new insights into the evolution of scorpions' immune systems. In a phylogenetic context, do species that depend on their pincers for subjugating the prey and rely less on venom (Garcıá et al, 2022) have "stronger" immune systems? Given that those species also tend to have less potent venoms (Forde et al, 2022), this prediction only holds if the same toxins acting on prey or predators have antimicrobial properties as well.…”