| Cerastes cerastes | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Reptilia |
| Order: | Squamata |
| Suborder: | Serpentes |
| Family: | Viperidae |
| Subfamily: | Viperinae |
| Genus: | Cerastes |
| Species: | C. cerastes |
| Binomial name | |
| Cerastes cerastes (Linnaeus, 1758) |
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| Synonyms | |
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Cerastes cerastes is a venomous viper species native to the deserts of Northern Africa and parts of the Middle East. They often are easily recognised by the presence of a pair of supraocular horns, although hornless individuals do occur.[2] No subspecies are currently recognised.[4]
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The average length is 30–60 cm (0.98–2.0 ft), with a maximum of 85 cm (33 in). Females are larger than males.[2]
One of the most distinctive characteristics of this species are the supraorbital horns, one over each eye. However, these may be reduced in size or absent (see Cerastes).[2] The eyes are prominent and set on the side of the head.[5] 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).[2][6]
The colour pattern consists of a yellowish, pale grey, pinkish, reddish or pale brown ground colour that almost always matches the substrate colour where the animal is found. Dorsally, a series of dark, semi-rectangular blotches run the length of the body. These may or may not be fused into crossbars. The belly is white and the tail may have a black tip, the tail is usually thin.[2][5]
Common names of this species include Saharan horned viper,[2] horned desert viper,[3] Sahara horned viper,[5] desert horned viper, North African horned viper,[7] African desert horned viper, greater cerastes,[8] asp and horned viper.[9] In Egypt it is called el-ṭorîsha (حية الطريشة).
Arid north Africa (Morocco, Mauritania and Mali, eastward through Algeria, Tunisia, Niger, Libya and Chad to Egypt, Sudan, Ethiopia and Somalia) through Sinai to the northern Negev of Israel. In the Arabian Peninsula, it occurs in Yemen, extreme southwestern Saudi Arabia and parts of the country in Qatar where it is sympatric with C. gasperettii. A report of this species being found in Lebanon is unlikely, according to Joger (1984). Originally, the type locality was listed only as "Oriente." However, Flower (1933) proposed "Egypt" by way of clarification.[1]
These snakes favour dry, sandy areas with sparse rock outcroppings, and tend not to prefer coarse sand. Occasionally, they are found around oases, and up to an altitude of 1500 metres. Cooler temperatures, with annual averages of 20°C or less, are preferred.[2]
They typically move about 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. Having strongly keeled scales, this produces a rasping noise, similar to Echis. They are capable of striking quickly.[2]
In captivity, mating was observed in April and always occurred while the animals were buried in the sand.[2] 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 in length.[5]
C. cerastes venom is not very toxic, although it is reported to be similar in action to Echis venom.[2] Envenomation usually causes swelling, haemorrhage, necrosis, nausea, vomiting and haematuria. A high phospholipase A2 content may cause cardiotoxicity and myotoxicity.[5] 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.[2] For venom toxicity, Brown (1973) gives LD50 values of 0.4 mg/kg IV and 3.0 mg/kg SC.[7] An estimated lethal dose for humans is 40–50 mg.[5]
A number of subspecies may be encountered in literature:[2]
Previously, C. gasperettii was also regarded as a subspecies of C. cerastes.[2]