Discovery in Colombia of a new species of scorpion that “sprays” venom! Should we be worried?

The scorpion T. achilles is capable of releasing venom from its stinger (image on the left), as well as “ejecting” a toxic secretion (visible in the form of white spots on the body of the animal on the right). Image: adapted from Laborieux (2024).

The scorpion is an arthropod of the arachnid class, very feared throughout the world, and no wonder… Some species have deadly venom that can kill in a short time; and they claim several victims each year. What is also worrying is that they are small animals and they hide, making it sometimes difficult to see them clearly.

There are currently around 2,200 known species of scorpions in the world, which live in both rainforests and deserts. Around 160 of them are present in Brazil.

Now, a study published in the Zoological Journal of the Linnean Society reveals the discovery of a new species of scorpion that projects its venom into the air as a defense mechanism, a rare behavior among these arachnids. The animal was discovered in Colombia. See below for more details on the discovery.

Defense mechanism consisting of “ejecting” venom

The new species, named Tityus achilles (T. achilles), has the ability to “spray” venom into the air. This behavior had previously only been observed in two genera of scorpions in North America and Africa; this is the first time it has been observed in a South American scorpion. The animal was discovered in a mountainous area of the Magdelena rainforest, in the department of Cundinamarca, Bogota.

Normally, scorpions inject their venom using their tail, called the metasoma, where the stinger which inoculates the substance and the glands which produce the venom are located.

Anatomy of the scorpion species T. achilles. Image: Adapted from Laborieux (2024). — Anatomy of the Scorpion Species *T. achilles*. Image: Adapted from Laborieux (2024).

However, in this species, the animal can project a jet of venom at its predator, which may be enough to distract it and stop it, thus allowing the arachnid to escape, without necessarily killing its opponent.

The purpose of spraying poison is therefore to distract the predator. and not necessarily to kill it or its prey.

Is the strategy effective?

According to research, this strategy can help the animal escape, but it is not as effective as the sting itself, as the expelled jet of venom may not hit the desired target precisely.

This technique of diffusing toxins has already been observed in other organisms, for example in snakes which can “spit” venom at their adversaries, in arthropods, molluscs and mammals.

Furthermore, Léo Laborieux, student at the Ludwig Maximilian University of Munich (Germany) and author of the article, explains in a press release that these toxins must reach very sensitive tissues to have a real effect. “And for that to make sense, the predator has to be a vertebrate. The toxins would have difficulty penetrating the exoskeleton of another invertebrate,” he said.

It is possible that this spray is a sort of “pre-poison”, a toxin released before the poison itself, which is much more powerful, according to the researcher.

And like T. achilles can also sting, it is natural to infer that spraying venom is a more conservative defense mechanism. “Venom spraying is an inherently expensive strategy. It is likely that very intense selection pressure makes this behavior more advantageous than disadvantageous. There must be something going on with the predators in the environment,” concludes Laborieux.