Cerastes cerastes
Desert Horned Viper

Sahara horned vipers are among the most abundant and easily distinguishable of the venomous snakes of the North African and Middle Eastern deserts. Cerastes cerastes is generally distributed all across North Africa, including southwestern Arabia and southwestern Israel. Common in the Sahara desert, it is most frequently found between Egypt and Morocco. Its range extends to southward to northern Mali, Niger, northern Chad, Sudan, and Mauritania.

Although records are rare in the southern Saharan borderlands, this snake has been reported within the Sahel, the sub-steppe region of the Sahara. Interestingly, C. cerastes is also known to inhabit the deserts of the eastern Sinai, coexisting with the Arabian horned viper, Cerastes gasperetti mendelssohni. (Branch and Spawls, 1995; Cox, et al., 2006; Johann, 1973; McGinley, 2007; Morain and Young, 2003; Schneemann, et al., 2004)

Found throughout the Sahara in Northern Africa, C. cerastes inhabits a variety of habitats within the desert, including rock hills, sandy deserts, and wadis. Members of this species can sometimes be found in dunes, and are rarely found on rock pavement and gravel plains.

It has been determined that there is a strong correlation between microclimate and the general distribution of this species. Saharan horned vipers generally prefer cooler temperatures, with annual averages of 20°C or lower, and are usually found in altitudes of up to 1500m. Even humidity is important when considering the locality of these snakes. Temperatures must be high enough for the snake to bask and obtain heat, and humid enough to retain a maximum amount of water present in the body, as the only source of water is from prey. ("Cerastes cerastes (Desert Horned Viper)", 2004; Johann, 1973; Mermod, 1970; Norris, 2000)

Sahara horned vipers are amongst the most distinct of the North African desert snakes. Compared to most snakes in the region, this species is short in length, averaging between 30 and 60 cm. Hatchlings are usually between 12 and 15 cm. Although females are larger, both sexes share the same general body structure and color patterns. The head is somewhat flat, broad, and triangular, with eyes on the side of the head, and the neck is thin.

Covered in approximately 25 to 35 rows of heavily keeled scales, C. cerastes is characterized by the presence of supraorbital “horns”, which consist of a single scale above each eye, from which a dark line extends towards the back of snake. This feature is what generally distinguishes Sahara horned vipers from other species of the genus Cerastes, as Cerastes gasperetti mendelssohni has horns that consist of multiple scales, and Cerastes vipera has its eyes on the top of the head. Prominent brow ridges typically ensue the lack or reduction of these horns. (Blanc, 1986; Branch and Spawls, 1995; Mermod, 1970)

The body is broad and appears flat, with a short tail which may have a black tip. This species is brownish-yellow and gray in color, perfectly blending into the sandy environment in which it lives. Dorsally, it also has rectangular brown patches that are darker in color than the rest of the body. (Disi, 1983; George, 2002)

As an oviparous species, Cerastes cerastes offspring development occurs outside of the mother's body, in the fertilized eggs she lays. An increase in oxygen consumption allows the snake to experience an exponential growth pattern throughout embryonic development, and normal respiration rates are assumed after hatching. (Cox, et al., 2006; George, 2002; Ludwig, et al., 2003)

Information regarding the mating systems of C. cerastes is data deficient. However, it has been observed that this species typically breeds during the first few weeks of April. In addition, it is assumed that members of the opposite sex locate and attract each other through the use of pheromones. (George, 2002; Ludwig, et al., 2003)

Copulation is generally observed during the first week of April and always occurs while buried under the sand. It is unknown whether these snakes breed annually. In a case of two captive individuals, copulation lasted for 4 days. Cerastes cerastes generally oviposits anywhere from 8 to 23 eggs, usually under rocks or in abandoned burrows of reptiles and mammals. The young hatch after a 50 to 80 day incubation period. Juvenile Cerastes cerastes reach reproductive maturity at 2 years of age. (Brodie Jr. and Campbell, 1992; George, 2002; Ludwig, et al., 2003)

There is no information currently available concerning the parental investment of Cerastes cerastes.

Although very little is known concerning the lifespan of individuals in the wild, specimens in captivity have been observed to survive for up to 18 years. (Branch and Spawls, 1995; Ludwig, et al., 2003)

Consistent with numerous taxa of the Squamata order, Cerastes cerastes exhibits a great deal of fossorial behavior. Beginning at the posterior end, the snake extends its body anteriorly into the sand, usually until only its eyes and nostrils are exposed. During the day, it may hide in burrows or holes made by other animals, under wood or rocks, or even in bushes. It is most often found buried or partially buried in soft sand, avoiding the scorching heat as well as using its camouflage to capture potential prey. Sahara horned vipers are generally even-tempered snakes, but they are capable of administering toxic venom if threatened. When disturbed, the snake produces a hissing and crackling sound from the shaking and rubbing of its coils, and does so as a warning before striking.

Sidewinding is the primary method of locomotion for C. cerastes and the majority of desert snakes. This type of movement allows the snake to move quickly across the desert sands by lifting a loop of the body and moving it forward, while the rest of the body follows the moving loop. This also assists in preventing the snake from overheating, as minimum contact between the belly and the ground is maintained throughout the movement.

Hibernation occurs from January to February, but is interrupted by warm days throughout the winter days. By late March, activity increases, and foraging mainly occurs at night. (Cox, et al., 2006; Ludwig, et al., 2003; Mermod, 1970; Schneemann, et al., 2004)

There is currently no information available regarding the home range of Cerastes cerastes. (Branch and Spawls, 1995)

As specialized semi-fossorial snakes, all members of the genus Cerastes exhibit predatory launch strikes from partially buried positions in the Saharan sands. As such, the majority of the communication and perception techniques demonstrated by these snakes incorporate multiple environmental stimuli in order to enhance prey localization and acquisition. Through multiple studies and experiments, it has been found that foraging by vibration detection is particularly significant in C. cerastes, as well as other members of the genus. Additionally, visual capabilities are pertinent in strike accuracy and distance, although the snake is still quite capable of capturing prey with hindered vision. Interestingly, prey capture behavior does not seem to be limited by olfactory senses, and in contrast to common belief, chemosensory reliance in Cerastes during foraging is nearly negligible, as visual stimuli act as primary determinants of prey apprehension. (McGinley, 2007; Morain and Young, 2002; Morain and Young, 2003)

When communicating with other members of its own species, Sahara horned vipers rely mostly upon chemical signals in the form of pheromones. This is used particularly during the mating season, as it acts to locate members of the opposite sex. Also, C. cerastes makes use of vibrational stimuli and the ability to sense heat from other organisms in the environment from its pit organs in order to locate prey. Located just behind the nostrils, the pit organs in these snakes allow them to detect warm-blooded animals, even in the dark. (Cox, et al., 2006; Morain and Young, 2002; Morain and Young, 2003)

The diet of this carnivorous species consists primarily of small rodents, geckos, birds, and a variety of lizards. In captivity, a full grown specimen was observed to feed on weaver finches (Passer domesticus niloticus), lacertids (Mesalina olivieri), and dune geckos (Stenodactylus petrii). These vipers are also known to eat jerboas (Jaculus jaculus), yellow wagtails (Motacilla flava thunbergi), and chiffchaffs (Phylloscopus collybita). Cerastes cerastes has been known to travel long distances at night in search of prey. ("Cerastes cerastes (Desert Horned Viper)", 2004; George, 2002; Ludwig, et al., 2003)

Sahara horned vipers are known to have only a few natural enemies, including honey badgers, monitor lizards, and a variety of wild and feral cat species. The snakes' colors provide optimum camouflage, working in their favor as both predators and prey. In addition, although C. cerastes burrows in order to stay cool during the day, as well as to attack unsuspecting prey, this behavior may also help hide it from potential predators. (Brodie Jr. and Campbell, 1992; Cox, et al., 2006; Johann, 1973)

This species is a particularly successful predator throughout the Sahara. With only a few known predators, it can be inferred that C. cerastes acts to limit the population sizes of the prey upon which it feeds. (Disi, 1983; Ludwig, et al., 2003)

As a very successful predator across the Sahara, C. cerastes acts to control populations of rodents that disturb livestock and other food sources of the native people of the region. In some areas, local people consider the snake to be of no particular danger, and the species is even tolerated around some villages. In contrast, other regions fear the snake, and believe it to have powers and even that it is capable of flying. Some native snake charmers use C. cerastes because of their horns, and large numbers of the species have been observed for sale at tourist resorts.

In addition, the venom derived from Sahara horned vipers provides a great deal of information concerning certain enzymes and their effects on reptilian and mammalian biochemical processes, as well as assist in the production of antivenins that are used for a variety of African snake species. (Blanc, 1986; Ludwig, et al., 2003; O'Shea, 2008)

A venomous snake, Cerastes cerastes is capable of inflicting damage to its prey, but also bites when threatened. Common amongst all three species of Cerastes, the venom is cytotoxic, affecting the walls and contents of cells, yet is not very toxic when compared to most other snakes in the region.

Despite the widespread distribution of Sahara horned vipers, their relatively hostile habitats result in few humans bitten, and therefore little statistical data is available concerning C. cerastes bites. However, venomous bites have been known to cause swelling, nausea, hemorrhaging, vomiting, necrosis, and hematuria. Bites should be treated immediately with elevation, analgesics, and antibiotic cover. For more serious bites, supply of an appropriate antivenin is required. (Branch and Spawls, 1995; Ludwig, et al., 2003; Schneemann, et al., 2004)

According to the International Union for Conservation of Nature (IUCN) Center for Mediterranean Cooperation, Cerastes cerastes is considered a species of “Least Concern” in terms of its conservation status. In fact, all three species of Cerastes are not of particular concern in the Mediterranean Basin.

A region relatively rich in biodiversity, the Mediterranean Basin is regarded as a biodiversity hotspot due to the abundance of threatened plant endemism that occurs. The primary threat to reptilian populations is habitat loss and degradation, mainly due to human activities. Pollution, the introduction of alien species, and general human disturbance are among the largest impacts to these populations. It is important to note that snakes are generally affected to the highest degree, however, only a few are actually considered threatened. (Cox, et al., 2006; Johann, 1973; McGinley, 2007; Werner and Sivan, 1992)