A newly discovered scorpion species in Colombia has stunned scientists with its ability to spray venom, a behavior previously only recorded in two genera from North America and Africa. The species, named Tityus achilles, was found in the Magdalena rainforest within the Cundinamarca department. This rare discovery, published in Zoological Journal of the Linnean Society, not only expands knowledge of scorpion defense mechanisms but also raises new questions about predator-prey dynamics in the region.
A Scorpion Unlike Any Other in South America
Most scorpions use their venom exclusively through a stinger to inject toxins into their prey or deter predators. However, Tityus achilles is unique because it can both inject and spray its venom—a trait that is extremely rare among arachnids.
The venom-spraying mechanism allows the scorpion to defend itself from a distance, potentially blinding or disorienting predators. The ability to spray venom has been documented in only two other scorpion genera: Parabuthus in Africa and Hemiscorpius in North America.
This makes T. achilles the first recorded species in South America to exhibit this defensive adaptation.
Why Does Tityus Achilles Spray Its Venom?
Scientists believe that venom-spraying is a high-cost survival strategy, meaning that it is only used when absolutely necessary. Producing venom requires significant energy, and wasting it on ineffective attacks could be disadvantageous. This suggests that T. achilles evolved this mechanism due to high predation pressure in its environment.
Léo Laborieux, the lead researcher and a former master’s student at Ludwig Maximilian University of Munich, explained that venom-spraying works best when targeting vertebrates, particularly those with sensitive areas like the eyes or nose. This indicates that the scorpion’s main threats are likely mammals or birds, rather than other arthropods.
How Scientists Observed the Venom-Spraying Mechanism
To study this rare behavior, researchers conducted experiments with Tityus achilles by gently pinning specimens down with a straw and recording their reactions. The scorpions responded by spraying venom 46 times, with some streams reaching up to 14 inches (36 cm).
The venom was expelled in two distinct ways: in some cases, the scorpions released quick venom flicks, producing tiny droplets, while in others, they emitted sustained sprays, forming a visible stream of toxin.
Most sprays were directed forward, seemingly aimed at a potential attacker’s face, but some were also projected upward or backward, depending on the scorpion’s position and level of distress.
The Secret Behind the Venom Composition
The composition of the venom plays a key role in its effectiveness. Researchers noticed that many of the initial venom sprays were transparent, while later ones had a milky tint. This suggests a two-stage defense mechanism:
- Pre-venom: A weaker, more easily produced toxin that serves as an initial deterrent. It is transparent and used in quick flicks or warning sprays.
- True venom: A potent, protein-rich toxin that is much more expensive to produce. This is typically injected through the stinger when a scorpion needs to subdue prey or deliver a final defense.
A New Perspective on Scorpion Evolution
The discovery of Tityus achilles challenges previous assumptions about scorpion venom delivery. It suggests that other scorpion species might also be capable of spraying venom but simply don’t use the ability under normal conditions.
Additionally, this finding expands the study of toxungens—toxins that are externally applied rather than injected. Other animals, like spitting cobras and certain amphibians, use similar mechanisms, but this is one of the few confirmed cases among arachnids.
