Non-aggressive competition in Srilankametrus yaleensis and a review of other types of agonistic behavior in scorpions

 

Competition happens in scorpions, both between species and within the same species. The cause of competition can be food, territory, hiding places, mates etc. As with many other animals, competition and other types of encounters do not have to be aggressive and cause damage.

Victoria Tang has recently published an article describing non-aggressive physical combat between adult males of Srilankametrus yaleensis (Kovařík et al., 2019) (Scorpionidae). The article also list other known examples of agonistic behaviors (intraguild or antipredatory) observed in scorpions.

The article is illustrated with many pictures illustration the different types of agonistic behavior. Video documentation can also be found in the supplemental materials.

Abstract:
A peculiar intraspecific agonistic behavior involving a non-aggressive physical combat is reported between the adult males of Srilankametrus yaleensis (Kovařík et al., 2019) (Scorpionidae: Heterometrinae). The adult males were observed to resort to a ritualized and relatively gentle way for strength demonstration. The combat is characterized by lateral spreading of pedipalps, chelicerae-to-chelicerae collision, and entanglement of metasomal segments. This behavior is hereby considered a form of an intrasexual combat defined as the “arm-span competition”. It is hypothesized to be beneficial for solving territorial and/ or sexual competitions while avoiding unnecessary mortality which could pose adverse impact to the natural populations. Other Heterometrinae species that possess sexually dimorphic, elongate pedipalps in males were also found to display similar behavior. This may account for at least one potential reason for the evolution of such sexual dimorphism. Finally, this study supplements several other agonistic behaviors (intraguild or antipredatory) observed in scorpions, with special attention to the family Scorpionidae. Three basic types of behavior are defined for this family: aggressive response, shielding response, and armspan competition. These types of behavior may have implications for the evolution of this family.

Reference:
Tang V. Non-aggressive competition between males of Srilankametrus yaleensis (Kovařík et al., 2019)(Scorpionidae), and other types of agonistic behavior observed in scorpions. Euscorpius. 2023;2023(368):1-17. [Open Access]