Cerastes cerastes

Cerastes cerastes, commonly known as the Saharan horned viper or the desert horned viper, is a venomous species of viper native to the deserts of Northern Africa and parts of the Arabian Peninsula and Levant. It is often easily recognized by the presence of a pair of supraocular "horns", although hornless individuals do occur. Three subspecies have been described.

Description
The average total length (body and tail) is 30 - 60 cm, with a maximum total length of 85 cm. Females are larger than males.

One of the most distinctive characteristics of this species is the presence of supraorbital "horns", one over each eye. However, these may be reduced in size or absent (see genus Cerastes). The eyes are prominent and set on the sides of the head. There is significant sexual dimorphism, with males having larger heads and larger eyes than females. Compared to C. gasperettii, the relative head size of C. cerastes is larger and there is a greater frequency of horned individuals (13% versus 48%, respectively).

The colour pattern consists of a yellowish, pale grey, pinkish, reddish or pale brown ground colour, which almost always matches the substrate colour where the animal is found. Dorsally, a series of dark, semi-rectangular blotches runs the length of the body. These blotches may or may not be fused into crossbars. The belly is white. The tail, which may have a black tip, is usually thin.

Common names
Common names of this species include desert sidewinding horned viper, Saharan horned viper, horned s, Sahara horned viper, desert horned viper, North African horned viper, African desert horned viper, greater cerastes, asp and horned viper. In Egypt, it is called el-ṭorîsha (حية الطريشة); in Libya, it is called um-Goron (ام قرون).

Distribution and habitat
The snake is common in Iraq but is also found in Syria, Saudi Arabia, Palestine, Yemen, Jordan, Israel, Qatar, Mauritania, Morocco and Kuwait. They can also be found in parts of North Africa including Libya, Egypt, and Sudan.

Originally, the type locality was listed only as "Oriente." However, Flower (1933) proposed "Egypt" by way of clarification.

These snakes favor dry, sandy areas with sparse rock outcroppings, and tend to avoid coarse sand. Occasionally they are found around oases, and up to an altitude of 1500 m. Cooler temperatures, with annual averages of 20 C or less, are preferred.

Behavior
They typically move by sidewinding, during which they press their weight into the sand or soil, leaving whole-body impressions. Often, it is even possible to use these impressions to make ventral scale counts. They have a reasonably placid temperament, but if threatened, they may assume a C-shaped posture and rapidly rub their coils together. Because they have strongly keeled scales, this rubbing produces a rasping noise, similar to the sound produced by snakes of the genus Echis. In the wild, they are typically ambush predators, lying submerged in sand adjacent to rocks or under vegetation. The diet of this carnivorous species consists primarily of small rodents, geckos, birds, and a variety of lizards. These vipers are also known to eat jerboas, yellow wagtails, and chiffchaffs. C. cerastes has been known to travel long distances at night in search of prey. When approached, they strike very rapidly, holding on to the captured prey until the venom takes effect.

Reproduction
In captivity, mating was observed in April and always occurred while the animals were buried in the sand. This species is oviparous, laying 8–23 eggs that hatch after 50 to 80 days of incubation. The eggs are laid under rocks and in abandoned rodent burrows. The hatchlings measure 12–15 cm (about 5–6 inches) in total length.

Venom
Cerastes cerastes venom is reported to be similar in action to Echis venom. Envenomation usually causes swelling, haemorrhage, necrosis, nausea, vomiting, and haematuria. A high phospholipase A2 content may cause cardiotoxicity and myotoxicity. Studies of venom from both C. cerastes and C. vipera list a total of eight venom fractions, the most powerful of which has haemorrhagic activity. Venom yields vary, with ranges of 19–27 mg to 100 mg of dried venom being reported. For venom toxicity, Brown (1973) gives values of 0.4 mg/kg IV and 3.0 mg/kg SC. An estimated lethal dose for humans is 40–50 mg.

Taxonomy
A number of subspecies have been described:
 * Cerastes cerastes hoofieni Werner & Sivan, 1999 – Saudi Arabia.
 * Cerastes cerastes karlhartli Sochurek, 1974 – Egyptian horned viper – southeast Egypt and Sinai Peninsula.
 * Cerastes cerastes mutila Domergue, 1901 – Algerian horned viper – southwest Algeria, Morocco.

Previously, C. gasperettii was also regarded as a subspecies of C. cerastes.