Thanatosis, or tonic immobility, is a behavior where animals adopt a motionless posture after a physical contact or very close proximity of a predator. This behavior has been described in a wide range of taxa, from invertebrates to vertebrates. For scorpions, tonic immobility has been reported in two buthids, Tityus pusillus and Tityus cerroazul, one hormurid, Liocheles australasiae, and one scorpiopsid, Scorpiops jendeki. Here we report other cases of this thanatosis for two buthid scorpions from lower Central America: Tityus ocelote and Ananteris platnicki. Thanatosis in these species were observed in wild, but was better documented in the laboratory. After human handling, several individuals for both species rolled over and laid on their back, adopting a distinctive rigid position, where they did not respond to external mechanical stimuli. As tonic immobility might be associated with other defense strategies, such as cryptic colorations, it is hypothesized that this behavior is used as a strategy in both species only if there is physical contact that simulated by a predator. On the other hand, the observations of thanatosis we reported here and the ones reported in other Tityus scorpions suggest that this behavior may have a phylogenetic basis in American buthids and that it could be more widespread than initially thought. However, more observations of tonic immobility in buthids would allow the evaluation of this hypothesis.
Triana, F., Bonilla, F., Alfaro-Chinchilla, A., Víquez, C., Díaz, C., & Sasa, M. 2022 . Report of thanatosis in the Central American scorpions Tityus ocelote and Ananteris platnicki (Scorpiones: Buthidae). Euscorpius, No. 359: 1-5.