The horned adder (''Bitis caudalis'') is a

viper The Viperidae (vipers) are a family of snakes found in most parts of the world, except for Antarctica, Australia, Hawaii, Madagascar, and various other isolated islands. They are venomous and have long (relative to non-vipers), hinged fangs tha ...

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

. It is found in the

arid A region is arid when it severely lacks available water, to the extent of hindering or preventing the growth and development of plant and animal life. Regions with arid climates tend to lack vegetation and are called xeric or desertic. Most ar ...

region of southwest

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

, 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 In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...

are currently recognized. Like all other vipers, it is

venomous Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved ''venom apparatus'', such as fangs or a sti ...

Common names

The species is commonly known as the horned adder,Spawls S, Branch B. 1995. ''The Dangerous Snakes of Africa''. Ralph Curtis Books. Dubai: Oriental Press. 192 pp. . horned puff adder,Mallow D, Ludwig D, Nilson G. 2003. ''True Vipers: Natural History and Toxinology of Old World Vipers''. Krieger Publishing Company, Malabar, Florida. 359 pp. . or horned viper.U.S. Navy. 1991. ''Poisonous Snakes of the World''. US Government. New York: Dover Publications Inc. 203 pp. .

Description

A short, stout little viper, it usually averages in total length (body + tail). The largest specimen reported being seen is a female from southern

Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...

measuring total length.

Geographic range

The snake is found in far arid regions of southwest Africa: southwest

Angola , national_anthem = " Angola Avante"() , image_map = , map_caption = , capital = Luanda , religion = , religion_year = 2020 , religion_ref = , coordina ...

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

, across the

Kalahari Desert The Kalahari Desert is a large semi-arid sandy savanna in Southern Africa extending for , covering much of Botswana, and parts of Namibia and South Africa. It is not to be confused with the Angolan, Namibian, and South African Namib coastal de ...

of southern

, into northern

Transvaal Transvaal is a historical geographic term associated with land north of (''i.e.'', beyond) the Vaal River in South Africa. A number of states and administrative divisions have carried the name Transvaal. * South African Republic (1856–1902; af, ...

and southwestern

Zimbabwe Zimbabwe (), officially the Republic of Zimbabwe, is a landlocked country located in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Botswana to the south-west, Zambia to the north, and Mozam ...

. In

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

, it is found from the northern

Cape Province The Province of the Cape of Good Hope ( af, Provinsie Kaap die Goeie Hoop), commonly referred to as the Cape Province ( af, Kaapprovinsie) and colloquially as The Cape ( af, Die Kaap), was a province in the Union of South Africa and subsequen ...

south to the

Great Karoo The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe !Orakobab or Khoemana word ''ǃ’Aukarob'' "Hardveld") is a semi- desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its ex ...

. Its type locality is given as "... the sandy districts north of the Cape Colony..." outh Africa

Habitat

Horned adders are mostly found in sparsely vegetated

desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...

and

semiarid A semi-arid climate, semi-desert climate, or steppe climate is a dry climate sub-type. It is located on regions that receive precipitation below potential evapotranspiration, but not as low as a desert climate. There are different kinds of semi-ar ...

scrub country.

Venom

Bites are assumed to be rare and no epidemiological data are available. Little information is available regarding the toxicity and amount of venom produced. Spawls and Branch (1995) reported an average yield of 85 mg of wet venom, while Christensen (1971) offered an value of 1.2 mg/kg IV.Brown JH. 1973. ''Toxicology and Pharmacology of Venoms from Poisonous Snakes''. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. . Other research has found the LD₅₀ to be between 0.15 and 0.22 mg/kg C Y Lee et al. 1982. "Site of action of caudoxin, a neurotoxic phospholipase A2 from the horned puff adder (Bitis caudalis) venom". Toxicon, 20(3), 637-647 Based on this LD₅₀ value, Spawls and Branch (1995) estimated about 300 mg of this venom would be required to kill an adult. They regarded this venom as one of the weakest of the genus, although the tests are conducted solely on mice, which might have a different reaction from humans to the venom. On the other hand, an older report by the U.S. Navy (1965, 1991) suggested it is highly toxic and a number of deaths have occurred as a result.U.S. Navy. 1965. ''Poisonous Snakes of the World''. US Government. Washington, District of Columbia: US Govt. Printing Office. 212 pp. According to Broadley and Cock (1975), envenomation symptoms in humans include swelling, severe pain, nausea, vomiting and shock. Blisters and necrotic ulcers may form around the bite site. The National Antivenom and Vaccine Production Centre in

Riyadh Riyadh (, ar, الرياض, 'ar-Riyāḍ, lit.: 'The Gardens' Najdi pronunciation: ), formerly known as Hajr al-Yamamah, is the capital and largest city of Saudi Arabia. It is also the capital of the Riyadh Province and the centre of the R ...

Saudi Arabia Saudi Arabia, officially the Kingdom of Saudi Arabia (KSA), is a country in Western Asia. It covers the bulk of the Arabian Peninsula, and has a land area of about , making it the fifth-largest country in Asia, the second-largest in the A ...

, produces a polyvalent antivenin that includes a paraspecific antibody that protects against bites from this species.''Bitis caudalis''
a
Munich AntiVenom INdex (MAVIN)
Accessed 21 April 2007. According to the U.S. Navy (1965, 1991), polyvalent antivenins produced by SAIMR and the

Pasteur Institute The Pasteur Institute (french: Institut Pasteur) is a French non-profit private foundation dedicated to the study of biology, micro-organisms, diseases, and vaccines. It is named after Louis Pasteur, who invented pasteurization and vaccines f ...

are said to be effective, while Mallow et al. (2003) reported currently available antivenins are of limited effectiveness. Viljoen et al. (1982) isolated a protein, a

neurotoxic Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specificall ...

phospholipase A₂, from the venom, which they called "caudoxin". According to Lee et al. (1983), this is a

presynaptic In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. Synapses are essential to the transmission of nervous impulses from ...

toxin similar to

bungarotoxin Bungarotoxins are toxins found in the venom of snakes and kraits. Bites from these animals can result in severe symptoms including bleeding or hemorrhage, paralysis and tissue damage that can result in amputation. The paralytic effects of venom are ...

, but with different binding sites.

Taxonomy

A number of authors, including Mertens (1955), use a trinomial to refer to this species, even though no subspecies are recognized.

References

External links

* . Accessed 1 March 2007. * . Accessed 1 March 2007. {{Taxonbar, from=Q1498639 Bitis Snakes of Africa Reptiles of Angola Reptiles of Botswana Reptiles of Namibia Reptiles of South Africa Reptiles of Zimbabwe Reptiles described in 1839 Taxa named by Andrew Smith (zoologist)