Vinegaroon

Vinegaroons are terrestrial arthropods of the Arachnid order Uropygi, also called Thelyphonida. Commonly known as ‘whip scorpions’ or ‘uropygids,’ these arachnids are found in tropical and subtropical regions worldwide.

The name ‘vinegaroon’ refers to their ability to discharge an offensive, vinegar-like liquid when threatened, while the term ‘whip scorpions’ originates from the presence of a whip-like flagellum in their abdomen.

Description

Size

The vinegaroon’s body length can range from 25 to 85 mm (1.0 to 3.3 inches), but most species are no longer than 30 mm (1.2 inches). However, the largest species belonging to the genus Mastigoproctus can reach up to 85 mm (3.3 inches).

Body Plan

Their bodies are divided into two main segments:

1. Cephalothorax (Prosoma)

Their prosoma features a pair of large, pincer-like pedipalps, which they use for capturing prey and defense. These pedipalps are often the most prominent feature of their appearance, resembling true scorpions. However, there is also an extra large spine on each palpal tibia. They typically have one pair of median eyes at the front of the prosoma and up to five pairs of lateral eyes on each side.

2. Abdomen (Opisthosoma)

The opisthosoma comprises 12 segments, the first of which forms a pedicel. Each of the next eight segments contains dorsal tergites that protect the internal organs of the abdomen. A long, sensory, whip-like flagellum composed of 30 to 40 units is found at the end of the opisthosoma.

Taxonomy

Initially, vinegaroons, whip spiders, and short-tailed whip scorpions were grouped under the order Pedipalpi. However, this order was later divided into Amblypygi and Uropygi, with Schizomida further separating from Uropygi into its own order.

Based on the World Uropygi Catalog, over 100 species of vinegaroons are distributed into 16 extant genera under the family Thelyphonidae.

• Family: Thelyphonidae
  • Genus: Etienneus (1 species, Etienneus africanus (African Whip Scorpion))
  • Genus: Ginosigma (2 species, including Ginosigma schimkewitschii)
  • Genus: Glyptogluteus (1 species, Glyptogluteus augustus)
  • Genus: Hypoctonus (19 species, including Hypoctonus formosus, Hypoctonus gastrostictus, Hypoctonus siamensis)
  • Genus: Labochirus (3 species, including Labochirus tauricornis)
  • Genus: Mastigoproctus (25 species, including Mastigoproctus giganteus (Giant Vinegaroon), Mastigoproctus colombianus, Mastigoproctus maximus)
  • Genus: Mayacentrum (3 species, including Mayacentrum pijol, Mayacentrum guatemalae)
  • Genus: Mimoscorpius (1 species, Mimoscorpius pugnator)
  • Genus: Ravilops (2 species, Ravilops wetherbeei)
  • Genus: Sheylayongium (1 species, Sheylayongium pelegrini)
  • Genus: Thelyphonellus (4 species, including Thelyphonellus amazonicus)
  • Genus: Thelyphonoides (1 species, Thelyphonoides panayensis)
  • Genus: Thelyphonus (45 species, including Thelyphonus doriae, Thelyphonus lawrencei, Thelyphonus sepiaris)
  • Genus: Typopeltis (13 species, including Typopeltis stimpsonii, Typopeltis crucifer, Typopeltis sinensis)
  • Genus: Uroproctus (1 species, Uroproctus assamensis)
  • Genus: Valeriophonus (1 species, Valeriophonus nara)
  • Genus: Mesoproctus (Extinct)
  • Genus:Mesothelyphonus (Extinct)

Distribution

They are distributed across tropical and subtropical regions, including continents such as Africa, Asia, and North and South America, but not in Europe and Australia.

Mastigoproctus giganteus is most common in Arizona and New Mexico, whereas the only vinegaroon species in Africa, Etienneus africanus, is endemic to Senegal, the Gambia, and Guinea-Bissau.

Habitat

These arachnids inhabit terrestrial habitats like grasslands, scrublands, pine forests, and deserts. They prefer dark and humid places and often hide under tree logs, rocks, rotting wood, and other debris.

Diet

Vinegaroons are carnivorous, feeding on worms, slugs, and insects like crickets, termites, and cockroaches. They also prey on other arthropods like scorpions, millipedes, and terrestrial isopods. Although they mostly feed on invertebrates, a few larger species, like those in the genus Mastigoproctus, sometimes consume small vertebrates like lizards.

Behavior

• Vinegaroons are nocturnal creatures that actively hunt at night. They usually spend their days hiding in burrows or other sheltered locations to avoid high temperatures.
• If threatened, they emit a sour-smelling mixture of acetic acid and caprylic acid from glands on their abdomen, which can repel predators.
• When it encounters prey, the vinegaroon firmly grasps it using its chelicerae and pedipalps. It then uses special teeth on the underside of the trochanters to incapacitate and crush the prey’s tissues.

Lifespan

These arthropods usually live for around seven to nine years.

Reproduction and Life Cycle

A male vinegaroon initiates reproduction by producing a spermatophore (a mass containing sperm), which is transferred to the female following some courtship behavior. During this period, the male holds the ends of the female’s first pair of legs in his chelicerae and deposits the spermatophore on the ground, which is then picked by the female using her genitals. Alternatively, in some species, males often use their pedipalps to force the spermatophore into the female’s body.

A few months later, the female seals herself in a secure burrow. It then extrudes up to 40 eggs within a membranous brood sac that preserves moisture and remains attached to the mother’s body. The female does not feed during this period and arches her opisthosoma upwards to prevent the brood sac from touching the ground. Over the next few months, the eggs develop into postembryos within the brood sac, with appendages slowly becoming visible.

On hatching, the white-colored young climb onto their mother’s back and attach themselves using special suckers. They creep out of the burrow when they resemble miniature adults with red pedipalps just after their first molt. The young develop gradually, undergoing four molts in about four years until adulthood.

Predators

They are preyed upon by frogs, lizards, certain species of ground birds, such as roadrunners, and small mammals like skunks, raccoons, armadillos, and shrews.