Giant Vinegaroon

Characteristics

Giant vinegaroons are a type of arachnid and thus have two body segments (the cephalothorax and the abdomen), 4 pairs of legs, and 8 eyes. The eyes are located on the cephalothorax-- 3 on the left side, 3 on the right, and two in front. Despite having 8 eyes, their vision is poor. The first pair of legs, called antenniforms, are long and thin, and used as sensory organs, while the other 3 pairs are used for walking. Giant vinegaroons are whip scorpions, which is like a scorpion without the stinging tail. Instead, they have a flagellum. The overall color ranges from reddish-brown to dark brown. Females typically have a wider body and smaller pedipalps than males.

Species Specifics

Within the genus Mastigoproctus, there are 15 species. The Giant vinegaroon, M. giganteus, has a total of 3 subspecies, all found in North America. Vinegaroons are also referred to as whip scorpions, though they are more closely related to spiders than scorpions. Another synonymous common name for this species is “grampus.”

Physical Characteristics

The giant vinegaroon can spray a substance composed of acetic acid from a glad at the base of the flagellum. This is how it gets the name vinegaroon. The spray is an irritant that will linger in the air. The giant vinegaroon has accurate aim. It will only spray when it is physically touched.

Ecology

Habitat

They can be found in deserts in the southwestern United States and Mexico, and in grassland and arid scrubland in Florida. They have been found in dry mountainous regions up to 6,000 meters.

Distribution

Not much is known about the distribution and home range of giant vinegaroons.

Diet

This carnivorous arachnid eats slugs, worms, and insects such as crickets, termites, and cockroaches.

Ecological Web

The giant vinegaroon is a predator, and therefore helps keep the populations of its prey in check. It is prey to coatis, raccoons, armadillos, and skunks, as well as other carnivorous animals.

Activity and Behavior

Activity Pattern

Giant vinegaroons hide in burrows or beneath rocks and logs during the day, and hunt prey during the night. They are most active during the rainy season, and stay underground during the driest seasons.

Behavior

Defensive posture is exhibited by having the abdomen and pedipalps raised, and the flagellum outstretched.

Social Behavior

Adults are solitary and aggressive. If they encounter another vinegaroon, they will fight with each other. Such fights may result in serious injury or death.

Reproductive Behavior

Mating occurs in the fall during the night. The courtship and mating combined may last up to 12 hours. In the event that a female is unwilling to mate, the male and female will fight and push each other away. However, if the female is willing, the pair will do a courtship “dance” which can last for hours. It consists of the male, having grabbed the female’s atenniform legs with his chelicerae, dragging her back then stroking her with his pedipalps. In response, the female will move backward and open her pedipalps, all the while the male still stroking her. This will repeat until the next stage, in which the male lays a sperm sac on the ground. This may take two hours to harden, and during that time the pair remains motionless. After it hardens, the female will pick it up and the male will push it inside her gonopore. This last part of the process may last up to two hours.

Offspring

20-40 eggs are laid once in a female’s lifetime. At first, the female will internally incubate them, and then she lays them in a fluid filled sac, and carries it by her abdomen for two more months, in which she will stay in her burrow. After both internal and external incubation is complete, the young, or nymphs, will hatch. Young are white, and stay on their mother’s back until their first molt, which happens after one month. The nymphs will molt four times before reaching adulthood.

Conservation

Status

Historical

The giant vinegaroon has been formally described and was first named in 1835 (Thelyphonus giganteus at the time), and went through several name changes until 1879 when it was named Mastigoproctus giganteus. Previous names include Thelyphonus excubitor in 1854 and Thelyphonus rufus in 1872.

Current Threats

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