While no single species is officially named a “spider snake,” there is a remarkable creature that perfectly embodies this description: the spider-tailed horned viper. This venomous snake, scientifically known as Pseudocerastes urarachnoides, possesses a unique tail that closely mimics the appearance and movement of a spider. Its unusual adaptation allows it to employ a specialized hunting strategy.
The Spider-Tailed Horned Viper
The spider-tailed horned viper (Pseudocerastes urarachnoides) is a species of viper belonging to the family Viperidae. These vipers are sometimes referred to as “false-horned vipers” due to the raised scales above their eyes that create a horned appearance. This medium-sized snake typically measures between 19.6 inches (50 centimeters) and 25.6 inches (65 centimeters) in length. Its coloration, which can range from grayish-brown to tan, allows it to blend seamlessly with its rocky surroundings. The species was formally described in 2006.
The Deceptive Tail
The most distinctive feature of Pseudocerastes urarachnoides is its tail. The tip of the tail is modified with a bulbous, fleshy end and elongated scales that splay outwards, creating the convincing illusion of a spider’s body and legs. This unique structure serves as a caudal lure, a deceptive mechanism used to attract prey. The snake wiggles its tail to enhance the illusion, mimicking the erratic movements of a crawling arachnid. This precise mimicry is so effective that birds and other small animals, mistaking the tail for an easy meal, are drawn within striking distance of the viper.
Habitat, Behavior, and Venom
The spider-tailed horned viper is native to the rocky desert regions of western Iran and extends into eastern Iraq, particularly within the Zagros Mountains. It prefers habitats with crevices and holes in rock formations, which provide shelter and ideal ambush points. As an ambush predator, the viper remains motionless, camouflaged against the terrain, with only its spider-like tail exposed. When a bird or other small animal approaches the lure, the viper strikes swiftly.
The venom of Pseudocerastes urarachnoides is primarily cytotoxic, meaning it targets and destroys various cell types, and it also exhibits procoagulant effects, rapidly causing blood to clot. While highly effective against its prey, there have been no recorded cases of human envenomation, and the full severity of its effects on humans remains unclear.