Deep in the rainforests of Colombia, a scientist set out to study moths. While searching for copper, he found gold: a new scorpion capable of something almost unheard of—spraying venom. The newfound species, known as Tityus achilles, can launch its toxins up to 36 centimeters away, an extraordinary adaptation that may help it fend off threats.
Well, What Were the Odds?
Léo Laborieux, then a master’s student at Ludwig Maximilian University of Munich, hadn’t planned to study scorpions. While working at a research station in central Colombia, he and a colleague set out to trap moths. When that failed, they turned their attention to scorpions. One poke with a stick, and something unusual happened.
“I noticed this weird line of small droplets on the side of the cup,” Laborieux told New Scientist. “The thought occurred to me that it could be venom spraying, but I didn’t really believe it.”
Back in the lab, videos confirmed it—this scorpion wasn’t just injecting venom with its stinger, like most of its kin. It could spray it outward, a behavior only seen in a handful of other scorpion species. It’s the first recorded case of venom spraying in a South American scorpion.
Ranged vs. Melee?
For a scorpion, a sting is usually a last resort. Direct injection ensures the venom reaches its target, but it also requires close contact—risky business if the predator fights back. Spraying offers a safer alternative. A well-aimed squirt of toxin to the face can startle an attacker just long enough for the scorpion to escape.
But not all predators would be affected. Scorpions often battle other arthropods—like spiders or centipedes—which have tough exoskeletons. A sprayed mist of venom would likely have little effect. Instead, Laborieux believes the behavior evolved to deter vertebrate predators, such as rodents, that might otherwise see the scorpion as an easy meal.
“These toxins need to reach very sensitive tissues to actually take effect,” Laborieux told Live Science. “For this to make sense, the predator has to be a vertebrate.”
An Adaptation That Comes with a Cost
Venom is a precious resource. Producing and replenishing it comes at a metabolic cost, which is why most venomous animals inject it directly into their targets. But spraying, while inefficient, has one clear advantage: it allows an animal to defend itself without physical contact.
“Venom projection is a wasteful delivery method that typically fails to maximize achieved toxicity for a given secreted quantity,” the authors note. However, they suggest that the ability to spray may have evolved because it significantly increases the scorpion’s chances of survival against predators.
“The venom itself is usually composed of higher molecular weight peptides and proteins, which are much larger, and for that reason, much more expensive to produce,” Laborieux explained.
The researchers also found that Tityus achilles conserves its more potent venom. Initial sprays consisted mostly of a clear, prevenom-like secretion. Only in high-threat situations did the new species release its opaque, more toxic venom.
A Rare Ability in the Scorpion World
With over 2,500 known scorpion species, venom spraying remains an extreme rarity. Before Tityus achilles, only two genera—one in North America and one in Africa—had been observed using this defense. The southern African Parabuthus transvaalicus, sometimes called the “spitting scorpion,” is one such case, and in at least one recorded case, it caused temporary blindness when it hit a person’s eye.
In a series of lab tests, researchers provoked Tityus achilles by pinning it down with a drinking straw. The study recorded 46 airborne attacks using high-speed video, revealing that the scorpion employs two distinct types of venom projections: “venom flicks” and “venom sprays.”.
Venom flicks, the researchers found, involve a rapid movement of the scorpion’s tail that flings small amounts of venom toward a target. Sprays, on the other hand, are more forceful expulsions, similar to the behavior seen in spitting cobras. The maximum reach of these venomous blasts was measured at 36 centimeters—far enough to potentially hit the eyes of an approaching predator.
Despite the threat, the researchers note that its potential risk to humans remains unclear. Most scorpion-related incidents in Colombia involve direct stings, and there are no documented cases of injuries caused by venom spraying. Given that the spray range is relatively short, a person would likely be at risk only if they were already close enough to be stung.
An Evolutionary Puzzle in the Colombian Rainforest
The discovery of Tityus achilles raises questions about what makes venom spraying a viable survival strategy. If most scorpions can spray but don’t, what’s different about the environment of Tityus achilles?
“There has to be something going on with the predators in the environment,” Laborieux speculated.
For now, the answer remains a mystery. But one thing is clear: this small arachnid, lurking in the shadows of the Colombian rainforest, has evolved an extraordinary way to defend itself. A warning spray, rather than a sting, may be just enough to keep its enemies at bay.
The findings appeared in the Zoological Journal of the Linnean Society.
