The Biochemistry of Defense: Vinegaroons

Here at the Monteverde Butterfly Gardens we have the decepetively named “tailless whip scorpion”, which is not a scorpion at all but an amplypygid. Slightly more difficult to pronounce but a much more accurate name. The amplipygid has no stinger, no venom, no defense mechanism at all really. For capturing prey it has are some modified front legs. She essentially hugs her prey to death via impalement, which is pretty neat, but not nearly as cool as the chemical defense the similarly named whip scorpion possesses.

Tailless whip scorpion, aka Amplypygid

The tailless whip scorpion, aka amplypygid, we have at the Monteverde Butterfly Gardens

So, kind of related: The whip scorpion, similar to the tailless whip scorpion only by name and being an arachnid, does has a chemical defense. As the name implies, this creature has a tail from which she can quite accurately, aim and spray a chemical defense: acetic acid, aka vinegar, which is where it gets it’s more appropriate name, the vinegaroon. So normally, vinegar is a very low percentage of acetic acid. The vinegaroon actually has the highest concentration of acetic acid found in nature: 84%.

Vinegaroon aka whip scorpion

Vinegaroon ready to spray 1

This chemical is used defensively, primarily other things with exoskeletons. The vinegaroon has a slight problem though. Although acetic acid is quite a wonderful defense on soft fleshy parts, it is water soluble and will roll off of an exoskeleton of it’s attacker without harming it. So it needs to employ another tactic. Mixed with the acetic acid is another acid, caprylic acid, which is able to move through the waxy cuticle of the exoskeleton. This mixture with spread to cover more area as well as actually getting under that exoskeleton so it can do some damage. In the end, when the mixture is actually shot out of two storage compartments in the vinegaroon it is composed of 84% acetic acid, 5% caprylic acid, and 11% water.

A Bombardier Beetle spraying a chemical mixture which is 100 degrees celcius!

A Bombardier Beetle spraying a chemical mixture which is 100 degrees celsius! 2

Chemical defense is quite amazing and is found in many species of insects and arachnids. One famous chemical defense is the bombadier beetle which uses a mixture hydroquinone and hydrogen peroxide from two separate chambers and shoots out a 100 degree celsius mixture at it’s predators. As there are many more insects waiting to be discovered and/or studied I’m sure we’ll be learning about many more amazing chemical defenses in the future.

In the meantime, poke insects you don’t recognize with care or you may find yourself smelling kind of funny.

Info from:

For Love of Insects by Thomas Eisner
Secret Weapons: Defenses of Insects, Spiders, Scorpions and Other Many Legged Creatures 2005 (Eisner, T., Eisner, M., Siegler, M.)

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