Arachnids · Thelyphonida · Thelyphonidae

Giant Vinegaroon

Mastigoproctus giganteus

Not Evaluated

It has not yet been assessed against the IUCN criteria. See full glossary

The giant vinegaroon is an arachnid of the order Uropygi (the whip scorpions). It has no sting; it does, however, have very powerful pedipalps. At dusk it hunts small insects, which it seizes with its pedipalps after locating them with its first pair of legs, which are long and serve as sensory organs. If threatened, it responds by squirting an acidic fluid from its anal glands, composed mainly of acetic acid (vinegar), hence its Spanish common name, vinagrillo. It grows to as much as 12 cm long and its range is North America. Despite its threatening appearance, it is entirely harmless to humans, since it has no venom.

Size

up to 6 cm

Diet

Carnivore

Feeds mainly on other animals.

Activity

Nocturnal

Active mainly at night.

Social structure

Solitary

Lives and hunts alone, joining others only to breed.

Sighting difficulty

Unknown

DesertCarnivore Nocturnal Solitary Desert Arachnid

2countries 33parks

Fun facts

GeneralIt fires a jet of concentrated acetic acid from its tail that smells strongly of vinegar.
It has neither venom nor sting, despite its looks. Its defence is a jet of 85 % acetic acid, fired with good aim from glands at the base of the tail, that smells strongly of vinegar. Hence the name vinegaroon.
The spray also contains substances that lower the surface tension of the attacker's cuticle, so that the acid spreads and penetrates better. The animal itself is immune to its own shot.
The long, thin tail is not a sting but a sensory organ, the flagellum.
It walks on six legs: the very long first pair serves as feelers for probing and picking up vibrations. It has eight eyes, but sees dreadfully and navigates by touch.
A 2018 study at the American Museum of Natural History split what had been called Mastigoproctus giganteus into several species: the Arizona population became M. tohono and the Florida one M. floridanus.