The puff adder (Bitis arietans) is a viperspecies found in savannahs and grasslands from Morocco and western Arabia throughout Africa except for the Sahara and rainforest regions.[3] It is responsible for causing the most snakebite fatalities in Africa owing to various factors, such as its wide distribution, frequent occurrence in highly populated regions, and aggressive disposition.[4][5] Like all other vipers, it is venomous. Two subspecies are currently recognized, including the nominate subspecies described here.[6]
The snake's typical size is about 1.0 m (39.3in) in total length (body and tail) and very stout. Large specimens of 190cm (75in) total length, weighing over 6.0kg (13.2lb) and with a girth of 40cm (16in) have been reported. Specimens from Saudi Arabia are not as large, usually no more than 80cm (31in) in total length. Males are usually larger than females and have relatively longer tails.[4]
B. arietans (adult)
The color pattern varies geographically. The head has two well-marked dark bands – one on the crown and the other between the eyes. On the sides of the head, two oblique, dark bands or bars run from the eye to the supralabials. Below, the head is yellowish white with scattered dark blotches. Iris color ranges from gold to silver-gray. Dorsally, the ground color varies from straw yellow, to light brown, to orange or reddish brown. This is overlaid with a pattern of 18–22 backwardly directed, dark brown to black bands that extend down the back and tail. Usually, these bands are roughly chevron-shaped, but may be more U-shaped in some areas. They also form two to six light-and-dark cross-bands on the tail. Some populations are heavily flecked with brown and black, often obscuring other coloration, giving the animal a dusty-brown or blackish appearance. The belly is yellow or white, with a few scattered dark spots. Newborn young have golden head markings with pinkish to reddish ventral plates toward the lateral edges.[4][7] One unusual specimen, described by Branch and Farrell (1988), from Summer Pride, East London, in South Africa, was striped. The pattern consisted of a narrow (one scale wide), pale yellowish stripe that ran from the crown of the head to the tip of the tail.[4] Generally, though, these are relatively dull-looking snakes, except for male specimens from highland East Africa and the Western Cape province of South Africa, that usually have a striking yellow-and-black color pattern.[7]
Puff adders have a form of olfactory crypsis which has been shown to make detecting them difficult for trained dogs and meerkats, both scent-based predators. The exact nature of this ability is not known, but is hypothesized to be related to a low metabolic rate, as well as relocation after shedding and defecating.[12]
The head has a less than triangular shape with a blunt and rounded snout. Still, the head is much wider than the neck. The rostral scale is small. The circumorbital ring consists of 10–16 scales. Across the top of the head, there are 7–11 interocular scales; three or four scales separate the suboculars and the supralabials. It has 12 to 17 supralabials and 13–17 sublabials. The first three or four sublabials contact the chin shields, of which only one pair exists. Often, two fangs are on each maxilla, and both can be functional.[4][7]
Midbody, the snake has 29–41 rows of dorsal scales. These are strongly keeled except for the outermost rows. The ventral scale count is 123–147, the subcaudals number 14–38. Females have no more than 24 subcaudals. The anal scale is single.[4]
It is found in all habitats except true deserts, rainforests, and (tropical) alpine habitats. It is most often associated with rocky grasslands.[13] It is not found in rainforest areas, such as along the coast of West Africa and in Central Africa (i.e., central DR Congo); it is also absent from the Mediterranean coastal region of North Africa. On the Arabian Peninsula, it is found as far north as Ta'if.[7] It has been reported to be found in the Dhofar region of southern Oman.[14]
Behaviour
Squirrel trailing a puff adder while sounding an alarm call to warn others
Normally a sluggish species, the puff adder relies on camouflage for protection. Locomotion is primarily rectilinear, using the broad ventral scales in a caterpillar fashion and aided by its own weight for traction. When agitated, it can resort to a typical serpentine movement of surprising speed.[4][13] Although mainly terrestrial, these snakes are good swimmers and can also climb with ease; often they are found basking in low bushes. One specimen was found 4.6 m above the ground in a densely branched tree.[4]
If disturbed, they hiss loudly and continuously, adopting a tightly coiled defensive posture with the forepart of their body held in a taut "S" shape. At the same time, they may attempt to back away from the threat towards cover. They may strike suddenly and fast, to the side as easily as forwards, before returning quickly to the defensive position, ready to strike again. During a strike, the force of the impact is so strong, and the long fangs penetrate so deeply, that prey items are often killed by the physical trauma alone. The fangs apparently can penetrate soft leather.[4][13]
They can strike to a distance of about one-third of their body length, but juveniles can launch their entire bodies forwards in the process. These snakes rarely grip their victims, but instead release quickly to return to the striking position.[4]
Puff adder puffing (Greyton, Western Cape, South Africa)
Feeding
Mostly nocturnal, they rarely forage actively, preferring, instead, to ambush prey as it happens by. Their prey includes mammals, birds, amphibians, and lizards.
Reproduction
B. a. arietans, juvenile (ready to strike)
Females produce a pheromone to attract males, which engage in neck-wrestling combat dances. A female in Malindi was followed by seven males.[5] They give birth to large numbers of offspring; litters over 80 have been reported, while 50–60 are not unusual. Newborns are 12.5–17.5cm in length.[13] Very large specimens, particularly those from East Africa, give birth to the highest numbers of offspring. A Kenyan female in a Czech zoo gave birth to 156young, the largest litter for any species of snake.[5][7]
Captivity
These snakes do well in captivity, but gluttony has been reported. Kauffeld (1969) mentions that specimens can be maintained for years on only one meal per week, but that when offered all they can eat, the result is often death, or at best wholesale regurgitation.[9] They are bad-tempered snakes, and some specimens never settle down in captivity, always hissing and puffing when approached.[5]
Venom
This species is responsible for more snakebite fatalities than any other African snake, due to a combination of factors, including its wide distribution, common occurrence, large size, potent venom that is produced in large amounts, long fangs, and their habit of basking by footpaths and sitting quietly when approached.[4][5][7]
The venom has cytotoxic effects[15] and is one of the most toxic of any vipers based on LD50.[4] The LD50 values in mice vary: 0.4–2.0mg/kg intravenously, 0.9–3.7mg/kg peritoneally, and 4.4–7.7mg/kg subcutaneously (SC).[16] Mallow et al. (2003) give an LD50 range of 1.0–7.75mg/kg SC. Venom yield is typically 150–350mg, with a maximum of 750mg.[4] Brown (1973) mentions a venom yield of 180–750mg.[16] About 100mg are thought to be enough to kill a healthy adult human male, with death occurring after 25hours.
In humans, bites from this species can produce severe local and systemic symptoms. Based on the degree and type of local effect, bites can be divided into two symptomatic categories – those with little or no surface extravasation, and those with hemorrhages evident as ecchymosis, bleeding, and swelling. In both cases, severe pain and tenderness occur, but in the latter, widespread superficial or deep necrosis and compartment syndrome are seen.[17] Serious bites cause limbs to become immovably flexed as a result of significant hemorrhage or coagulation in the affected muscles. Residual induration, however, is rare and usually these areas completely resolve.[4]
Other bite symptoms that may occur in humans include edema, which may become extensive, shock, watery blood oozing from the puncture wounds, nausea and vomiting, subcutaneous bruising, blood blisters that may form rapidly, and painful swelling of the regional lymph nodes. Swelling usually decreases after a few days, except for the area immediately around the bite site. Hypotension, together with weakness, dizziness, and periods of semi- or unconsciousness is also reported.[4]
If not treated carefully, necrosis will spread, causing skin, subcutaneous tissue, and muscle to separate from healthy tissue and eventually slough with serous exudate. The slough may be superficial or deep, sometimes down to the bone. Gangrene and secondary infections commonly occur and can result in loss of digits and limbs.[4][5][7]
The fatality rate highly depends on the severity of the bites and some other factors. Deaths can be exceptional and probably occur in less than 15% of all untreated cases (usually in 2–4 days from complications following blood volume deficit and disseminated intravascular coagulation), although some reports show that severe envenomations have a 52% mortality rate.[3][18] Most fatalities are associated with poor clinical management and neglect.[5][7]
Related Research Articles
Keeled scales refer to reptile scales that, rather than being smooth, have a ridge down the center that may or may not extend to the tip of the scale, making them rough to the touch. According to Street's (1979) description of European lizards and snakes, in those that have keeled scales the keels are usually stronger in male specimens and are consistently arranged according to the species of reptiles, even though many others do not have them. With European lizards, the dorsal scales are usually well keeled, while those on the flanks are more weakly keeled and those on the belly smooth. Non-European lizards such as Sphaerodactylus macrolepis also display keeled scales.
Vipera berus, also known as the common European adder and the common European viper, is a species of venomous snake in the family Viperidae. The species is extremely widespread and can be found throughout most of Central Europe and Eastern Europe, and as far as East Asia. There are three recognised subspecies.
The Gaboon viper, also called the Gaboon adder, is a viper species found in the rainforests and savannas of sub-Saharan Africa. Like all other vipers, it is venomous. It is the largest member of the genus Bitis, and it has the longest fangs of any venomous snake – up to 2 inches (5 cm) in length – and the highest venom yield of any snake. No subspecies are recognized.
Russell's viper, is a venomous snake in the family Viperidae native to the Indian subcontinent and one of the big four snakes in India. It was described in 1797 by George Shaw and Frederick Polydore Nodder, and named after Patrick Russell, who wrote about it in his 1796 work An account of Indian serpents, collected on the coast of Coromandel.
Hognose snake is a common name for several unrelated species of snake with upturned snouts, classified in 2 colubrid snake families and 1 pseudoxyrhophiid snake family.
Bitis is a genus of venomous vipers found in Africa and the southern Arabian Peninsula. It includes the largest and the smallest vipers in the world. Members are known for their characteristic threat displays that involve inflating and deflating their bodies while hissing and puffing loudly. The type species for this genus is B. arietans, which is also the most widely distributed viper in Africa. Currently, 18 species are recognized.
Bitis nasicornis is a viper species found in the forests of West and Central Africa. This large viper is known for its striking coloration and prominent nasal "horns". No subspecies are currently recognized. Its common names include butterfly viper, rhinoceros viper, and river jack. Like all other vipers, it is venomous.
Causus is a genus of vipers found only in sub-Saharan Africa. It is a group considered to be among the most primitive members of the family Viperidae based on head scalation, oviparity, venom apparatus, and because they have round pupils. However, this is contradicted by recent molecular studies. Seven species are currently recognized. They are commonly known as night adders. Like all other vipers, they are venomous.
Vipera ammodytes is a viper species found in southern Europe, mainly northern Italy, the Balkans, and parts of Asia Minor. Like all other vipers, it is venomous. It is reputed to be the most dangerous of the European vipers due to its large size, long fangs and high venom toxicity. The specific name, ammodytes, is derived from the Greek words ammos, meaning "sand", and dutes, meaning "burrower" or "diver", despite its preference for rocky habitats. Five subspecies are currently recognized, including the nominate subspecies described here.
Vipera aspis is a viper species found in southwestern Europe. Its common names include asp, asp viper, European asp, and aspic viper, among others. Like all other vipers, it is venomous. Bites from this species can be more severe than from the European adder, V. berus; not only can they be very painful, but approximately 4% of all untreated bites are fatal. The specific epithet, aspis, is a Greek word that means "viper." Five subspecies are currently recognized, including the nominate subspecies described here.
Bitis arietans somalica also known as the Somali puff adder, is a venomous viper subspecies found only in Somalia, eastern Ethiopia, and northern Kenya. It is distinguished from B. a. arietans by its keeled subcaudals.
The berg adder is a venomous viper species endemic to mountainous regions in southern Africa. No subspecies are currently recognized.
The horned adder is a viper species. It is found in the arid region of southwest Africa, in Angola, Botswana, Namibia; South Africa, and Zimbabwe. It is easily distinguished by the presence of a single, large horn-like scale over each eye. No subspecies are currently recognized. Like all other vipers, it is venomous.
Bitis parviocula is a venomous viper species found only in Ethiopia. It is large with a broad head and spectacular geometric markings. In 1995, the species was known from only three specimens, but additional information has surfaced since then. Little is known about its natural history or its venom. No subspecies are currently recognized.
Bitis peringueyi, also known as the Peringuey's adder, Peringuey's desert adder or desert sidewinding adder, is a venomous viper species found in Namibia and southern Angola. No subspecies are currently recognized.
Causus maculatus is viper species found mainly in West- and Central Africa. No subspecies are currently recognized. Common names include forest rhombic night adder, West African night adder and spotted night adder. Like all other vipers, it is venomous.
Causus rhombeatus, commonly known as the rhombic night adder, is a viper species endemic to subsaharan Africa. No subspecies are currently recognized. Like all other vipers, it is venomous.
The snouted cobra, also called the banded Egyptian cobra, is a highly venomous species of cobra found in Southern Africa.
1 2 McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Herpetologists' League. 511 pp. ISBN1-893777-00-6 (series). ISBN1-893777-01-4 (volume).
1 2 U.S. Navy. 1991. Venomous Snakes of the World. US Govt. New York: Dover Publications Inc. 203 pp. ISBN0-486-26629-X.
1 2 3 4 5 6 7 8 Spawls S, Howell K, Drewes R, Ashe J. 2004. A Field Guide to the Reptiles of East Africa. A & C Black Publishers Ltd., London. 543 pp. ISBN0-7136-6817-2.
↑ Widgerow AD, Ritz M, Song C. 1994. Load cycling closure of fasciotomies following puff adder bite. European Journal of Plastic Surgery 17: 40-42. Summary at Springerlink. Accessed 31 August 2008.
1 2 Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. ISBN0-398-02808-7.
↑ Davidson, Terence. "IMMEDIATE FIRST AID". University of California, San Diego. Archived from the original on 2 April 2012. Retrieved 14 September 2011.
Boulenger GA. 1896. Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the...Viperidæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers.) xiv + 727 pp. + Plates I.- XXV. (Bitis arietans, pp.493–495.)
Branch, Bill. 2004. Field Guide to Snakes and Other Reptiles of Southern Africa. Third Revised edition, Second impression. Sanibel Island, Florida: Ralph Curtis Books. 399 pp. ISBN0-88359-042-5. (Bitis arietans, pp.114–115 + Plates 3, 12.)
Broadley DG, Cock EV. 1975. Snakes of Rhodesia. Zimbabwe: Longman Zimbabwe Ltd. 97 pp.
Broadley DG. 1990. FitzSimons' Snakes of Southern Africa. Parklands (South Africa): J Ball & AD Donker Publishers. 387 pp.
Merrem B. 1820. Versuch eines Systems der Amphibien: Tentamen Systematis Amphibiorum. J.C. Krieger. Marburg. xv + 191 pp. + 1 plate. ("Vipera. Echidna. arietans", p.152.)
Pienaar U de V. 1978. The reptile fauna of Kruger National Park. National Parks Board of South Africa. 19 pp.
Sweeney RCH. 1961. Snakes of Nyasaland. Zomba, Nyasaland: The Nyasaland Society and Nyasaland Government. 74 pp.
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