The Vinegaroon: Its Unique Defense Mechanism Leaves a Bad Taste in Predator’s Mouth

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Tony Maples Photography


Have you ever seen a black scorpion-looking creature, sometimes as long as a credit card, prowling around outside at night? If you live in the Trans-Pecos region of Texas, you might be familiar with this menacing-looking critter. The whip scorpion, more commonly called a vinegaroon in Texas, is a member of the arachnid family but poses little danger to humans, unlike its cousins, the scorpion and the spider. It does, however, have a very unique defense mechanism that has been known to get this arachnid out of a “pickle,” a time or two.

Non-Poisonous but They Do Pinch!


Photo: Flickr/Richard Wasserman

The vinegaroon is considered non-poisonous but they can pinch and are capable of spraying a mist from scent glands at the base of the tail when disturbed. These glands, located right at the junction of the rear body segment (the abdominal segment, or “opisthoma”) and the base of the telson, (the last segment of the abdomen) produce a liquid mixture of a number of chemical compounds, but the stuff is primarily acetic acid and caprylic acid in many species.

They Shoot Acetic Acid: The Key Ingredient in Vinegar


Photo: Flickr/budak

You may know acetic acid as the key ingredient in vinegar, which is essentially 5% acetic acid by volume, which gives it its sour taste and characteristic odor. When threatened, vinegaroons jettison the watery contents of these glands through a pair of pivoting turrets, mounted on either side of the base of the telson in a spurt that can each about a foot away in any direction. With just enough agitation, the vinegaroon contracts the muscles around its dual tanks and lets the cocktail loose. If the solution hits a predator in the eyes, nose or mouth, you can bet that he’ll leave this pickled perpetrator alone.

It is the resulting noxious stink from these acidic emissions, reminiscent of common, household vinegar, that is at the origin of the “vinegaroon” name. The smell is particularly strong due to the concentration of acetic acid in the spray, which can be 15 times more concentrated than in vinegar.

Aside from the occasional unpleasant scent, the vinegaroon is harmless and eats other annoying insects like crickets and spiders. Some even keep vinegaroons as pets, citing their docile nature and ease of care.