Spider-tailed Horned Viper

## About

A spider-tailed horned viper displaying it's tail.

The spider-tailed horned viper ***(Psuedocerastes urarachnoides)*** also called the Iranian spider-tailed viper, is a species of viper that is named for the spider-shaped lure on the end of its tail. The spider-tailed viper has a ornate patterning consisting of a composition of dark browns, faded oranges, tans, whites and blacks all organised in a mottled arrangement across the body. The dark browns of the snake's colouration in particular are organised into diamond shapes across the body, which transition to a lighter gold patterning towards the tail. The head is triangular in shape, with rounded edges and scales that rise to frame the eyes, giving the species a 'horned' appearance. It is said that when compared to other viper species, the spider-tailed viper has much rougher and textured scales. This can be attributed to the species' use of camouflage in its mountainous cliffside habitat. The bulbous bony protrusion on the spider-tailed viper's tail resembles that of the camel spider ***(Galeodes arabs)***, which shares its range. The bulb is an orange or earthy yellow in colour and is surrounded by modified scales which are drawn out in lengths, similarly to the legs of the camel spider. When the spider-tailed horned viper was first discovered in 1968, the tail-bulb was initially dismissed as a genetic deformity however, when the species was later first described in 2006 by Iranian zoologist Hamid Bostanchi, he theorised that this was not a case of body dysmorphia, but rather a unique form of mimicry used in order to hunt bird species. Biologist Behzad Fathinia of Razi University, Iran, put Bostanchi's hypothesis to the test by enclosing a specimen with a chick. What transpired would prove Bostanchi correct, as the viper began to lure the bird by slowly shifting its tail from side-to-side, eventually striking. The spider-tailed viper is a relatively short species, only growing to 55-86cm (21-34in) in length.

## Diet

The spider-tailed viper hunts various species of birds which typically prey on insects. When hunting, the viper gyrates its tail in a hypnotic manor, slowly swinging it in a way similar to the way a camel spider would move. This display aims to make the bird believe that the tail is a true spider and eventually attempt to eat it. Once the bait is taken, the viper will then attack the bird, striking in a recorded time of 0.5 seconds. Though the species is most well-known for hunting birds, it is also a prolific hunter of lizards, rodents and arthropods. The spider-tiled viper is venomous and likely uses this attribute to further immobilise its prey once captured. Apparently, it has been reported that the lure on their tail can be broken off by birds, leaving the viper to devise other hunting methods however, this claim requires more documentation.

## Conservation Status

The threats of the spider-tailed viper are limited, as its habitat creates a barrier from most damaging human activity. The viper is known to be targeted surprisingly by the illegal international pet trade however, this is likely uncommon. This threat is only known from very few sources. The sources are as listed; social media posts including photographic evidence of a captive individual, a social media conversation from 2017 and a survey from the German Government for pet owners in 2018. Though this wild collecting of the viper may be rare, it could possibly lead to population detriment if unregulated. For this reason, the spider-tailed viper is listed as a near-threatened species by the IUCN.

## Range and Population

The spider-tailed viper inhabits the Zagros mountains of western Iran and a small portion of far eastern Iraq. It occurs at heights of up to 1,770m (5,807ft), in the arid cliffsides of the mountain range, camouflaging among the jagged rocks. Despite a highly specialised lifestyle and apparent dependence on cliffs, a spider-tailed viper was collected from an urban area. Though the population of the spider-tailed viper is unknown, it is likely in decline. Despite this, the species is apparently common.

## Behaviour

The spider-tailed viper actively seeks out areas of foliage, in fact, eight individuals were found in the vicinity of a lone ***(Ficus)*** tree. They will usually flock to small shrubs and such around the entrance of their burrows, which have cultivated in its range. As an ambush predator, the spider-tailed viper relies on keeping extremely still in order to hunt. The appearance of the viper assists in its lifestyle, as to a prey item, it appears to look similar to a rock. The species is known to brumate, emerging from its burrow in April to begin yearly above-ground activity, until brumation cycles restart in November. The breeding characteristics of the spider-tailed viper are currently unknown.

### Relationship with Humans

Though the spider-tailed viper is a venomous species (as are all vipers) the effects on which the venom has on humans is not well studied. Despite their venom, these snakes are not aggressive, likely only striking when threatened, aggravated or cornered. Although they are seemingly harmless unless provoked, rural villagers and locals who inhabit the viper's range will often kill the snake in self-defense.

## In Captivity

With the exception of its role as a possible exotic pet, the spider-tailed viper is not housed in any zoos, likely because of its specialised lifestyle, that is difficult to recreate in a captive environment.

## Sources

* IUCN Red List of Threatened Species - https://www.iucnredlist.org/species/164664/88004847
* Spider-Tailed Horned Viper | Wikipedia - https://en.wikipedia.org/wiki/Spider-tailed\_horned\_viper
* WATCH: The Spider-Tailed Viper Is Amazingly Good At Killing - https://www.sciencealert.com/watch-the-spider-tailed-viper-is-amazingly-good-at-killing
* CONVENTION ON INTERNATIONAL TRADE IN ENDANGERED SPECIES OF WILD FAUNA AND FLORA | CITES.Org - https://cites.org/sites/default/files/eng/cop/18/prop/060319/E-CoP18-Prop-32.pdf
* Spider-Tailed Horned Viper | A-Z Animals.Com - https://cites.org/sites/default/files/eng/cop/18/prop/060319/E-CoP18-Prop-32.pdf