In a historic event for science and South American biodiversity, a group of researchers has identified a new species of scorpion that sprays venom in Colombia, named Tityus achilles.
This finding represents a novelty for the region and a surprise, as the ability to spray venom is an extremely rare defensive mechanism in the animal kingdom.
A discovery led by experts
The discovery was led by Léo Laborieux, an associate scholar at Harvard University and an expert in evolutionary biology. The results were published in the Zoological Journal of the Linnean Society, opening a new perspective for the study of defense mechanisms of these arachnids and the evolution of their adaptations.
The Tityus achilles was found in the Cundinamarca region, in the mountain forests of the Eastern Cordillera, at 1,350 meters above sea level. This habitat, characterized by high humidity and moderate temperatures, constitutes an ideal refuge for a species that exclusively inhabits the forest floor.
Unique characteristics of the venom-spraying scorpion
With a body of approximately 6.5 centimeters in length, this scorpion has a dark reddish coloration and low fluorescence under ultraviolet light, an unusual trait among scorpions that could be related to an evolutionary strategy to avoid predators.
However, what truly distinguishes Tityus achilles is not only its habitat or appearance, but its astonishing ability to spray venom. So far, this behavior had only been documented in two genera of scorpions: Parabuthus, native to Africa, and Hadrurus, found in the southwest United States and northwest Mexico.
The new Colombian species sets a precedent as the first of its kind in South America to demonstrate this ability. According to Laborieux, in an interview with New Scientist, this ability probably evolved convergently in response to particular ecological pressures, such as the need to repel predators in its environment.
And how does the Tityus achilles spray its venom? In the form of small drops (“flicks”) or continuous sprays, reaching up to 36 centimeters away. Laborieux observed that both strategies have different energy costs: while individual drops are effective for short-range defenses, prolonged sprays are used as a last resort to deter more serious threats.
Furthermore, unlike other spraying scorpions, the Tityus achilles uses a compound known as pre-venom, less toxic and more metabolically economical, allowing it to conserve its more potent venom reserves for critical situations.
The accidental discovery of Tityus Achilles
The discovery of Tityus achilles was accidental. During fieldwork in Cundinamarca, aimed at studying moths, Laborieux and his team, unable to capture them, opted to catch scorpions instead.
While manipulating the specimens, they noticed small drops on the walls of the containers. Intrigued, they returned to the laboratory to confirm the phenomenon through high-speed recordings and ballistic equations analysis. In total, they conducted 46 experiments that allowed them to record the speed, trajectory, and volume of the expelled venom.
The scientist explained that venom spraying is a defensive mechanism that targets sensitive parts of predators, such as eyes or noses: “These toxins must reach extremely sensitive tissues to be effective”.
Although the impact on humans is low due to the lower toxicity of the pre-venom, the finding highlights the importance of avoiding direct contact with these animals.
Finally, Laborieux concluded in a scientific dissemination journal distributed in the UK, US, and Australia: “The biological diversity of Colombia is a window to evolutionary past and a responsibility for the future”.
Implications of the discovery
The implications of this discovery go beyond its biological uniqueness. On one hand, it offers a new perspective on defense mechanisms in arachnids and their evolution in different regions of the world. On the other hand, it raises questions about the ecological factors that led to the emergence of this ability in a Colombian ecosystem.
According to Laborieux, it will be crucial to investigate the differences in venom use between juvenile and adult specimens, as well as to analyze the chemical composition of the secretions.
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