Anatomy: large spiny pedipalps; first two legs used as antennae-like sensory organs; six legs used for walking; one pair of median eyes at the front of the cephalothorax and up to five pairs of lateral eyes on each side of the head; 12-segmented abdomen; glands near the rear of their abdomen can spray a combination of acetic acid and caprylic acid as a defense mechanism; long flagellum at end of abdomen acts as a sensory organ and can help with aiming the spray
Diet: smaller invertebrates such as insects, millipedes, scorpions, terrestrial isopods, worms, and slugs
Habitat: tropical and subtropical areas, excluding Europe and Australia; live in burrows under logs, rotting wood, rocks, and other natural debris
Evolved in: Carboniferous
Do you have a favorite in Uropygi?
One or more of my favorite animals is in Uropygi
I love at least one or more of these animals
I like at least one or more of these animals
I am neutral about all of these animals
I dislike all of these animals
Voting ended onSep 29, 2025
Propaganda under the cut:
Vinegaroon courtship rituals involve a dance that can last up to 12 hours of the female testing the male’s endurance. Males will also battle fiercely with each other for the chance to mate with females. Female vinegaroons invest a lot into their children, so they must be absolutely certain the male has good fitness. After mating, the female will seal herself inside her burrow and refuse to eat while she tends to her eggs, holding the eggsac under her abdomen and remaining motionless so that they do not touch the ground for the next few months. After the young hatch, they will climb onto their mother’s back and remain there until their first molt. After this, the babies will live with her in her burrow for a bit before their second molt. This can take up to a year to occur. In human care, the mother can be saved by feeding her during this time, but in the wild she will sometimes starve to death; expending all of her energy watching over her children. Females that survive child-rearing may live for another 2 years, but they will not mate again.
The African Whip Scorpion (Etienneus africanus) (image 4) is the only uropygid found in Africa, leading arachnologists to believe that it is a relict of Gondwana, the supercontinent that once included South America, Africa, Antarctica, Australia, Zealandia, Arabia, and India.
The Giant Whip Scorpion (Mastigoproctus giganteus) (image 1) is the largest uropygid, growing to be 40–60 millimetres (1.6–2.4 in) long, excluding the flagellum. They live in the southern US and Mexico, and are efficient predators of scorpions, sometimes even acquired as biocontrol for that purpose. The species is also sold in the pet trade, as they make a calm, non-venomous alternative arachnid to pet spiders or scorpions, though their vinegar-like spray can be irritating if it gets into eyes or cuts.
Vinegaroons spray a mixture of 85% acetic acid and 15% caprylic acid from the base of their whiplike flagellum. Acetic acid is one of the main ingredients in vinegar, giving the acidic spray its smell and vinegaroons their common name, though this spray is 15 times more concentrated than vinegar! They can accurately spray up to 12 inches in any direction, usually only when poked or prodded by a predator. They will spray the predator in the eyes, nostrils, or mouth, using the opportunity to run and hide while it’s distracted. Giant Whip Scorpions can spray up to 19 times before their store is depleted, and will be “recharged” by the next day. So as not to waste their supply of acid spray, they will give a warning by raising their abdomen, flagellum, and pedipalps in the air before spraying.
Very cool find from last spring- a Florida vinegaroon (Mastigoproctus floridanus) that was hiding inside a rotting log.
despite her impressive size, this rarely encountered Florida endemic is actually the smallest of the 3 vinegaroons in the US, and some of the Mastigoproctus species from Mexico and southwards get even larger.
and yes they’re called vinegaroons (among other fun names) because they squirt concentrated vinegar from their butt as a chemical defense
old timelapse of a Mastigoproctus tohono excavating a burrow I started for her. I miss keeping vinegaroons, there’s really nothing quite like them… although I wouldn’t want to have this particular species again—a seasonal desert lifestyle means they spend much of the year inactive and not eating.
