Bothrops atrox

Common names: common lancehead, fer-de-lance, barba amarilla.^[2]

Bothrops atrox is a venomous pitviper species found in tropical lowlands of northern South America east of the Andes.^[1] No subspecies are currently recognized.^[3] This species is very dangerous and is the cause of more human fatalities than any other American reptile.

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Description

Adults usually grow to total length 75-125 cm and are moderately heavy-bodied. Reports of the maximum size are not clear, as this species is often confused with B. asper. Soini (1974) mentioned that of a series of 80 specimens collected in northeastern Peru, the largest was a female of 138.8 cm. The largest specimen measured by Campbell and Lamar (2004) was a female with a total length of 162 cm.^[2]

The head is triangular and pointed due to large jaw muscles. Adults come in many shades of brown and olive (colors are variable), often with geometric markings that include pale stripes that may outline triangles on the back with their apexes at the spine. The underside of the head is pale yellowish.

Common names

Common lancehead, fer-de-lance, barba amarilla.^[2]

In Trinidad and Tobago, the snake is called mapepire balsain (pronounced ma-pa(y)-PEE BAL-sayn)^[4], while in Guyana it is called labaria^[5] or labarria.^[6] The Spanish common name barba amarilla (yellow beard), an allusion to the pale yellow chin color, is also used in English. In Colombia it is known as mapaná (Llanos of Vichada) and taya equis.^[2] The latter is an allusion to the x-like markings of the color pattern. In Ecuador these x-like markings have led to the snake simply being referred to as equis (the Spanish pronunciation of the letter 'x').

Geographic range

Found in the tropical lowlands of South America east of the Andes, including southeastern Colombia, southern and eastern Venezuela, Guyana, Suriname, French Guiana, eastern Ecuador, eastern Peru, northern Bolivia and the northern half of Brazil.^[1] It also occurs on the island of Trinidad.^[7] The type locality is listed as "Asia", which is obviously a mistake. Schmidt and Walker (1943:295) proposed that this be corrected to "Surinam."^[1]

Habitat

Despite the vast destruction of rain forests, it is amongst the most numerous of pit vipers and is not endangered. In Trinidad it prefers wet lowland forests.^[8]

Behavior

Although generally terrestrial, it is also an excellent swimmer and even climb trees when necessary to reach prey. Generally nocturnal, but may forage at any time of the day if necessary. These snakes are also very easily agitated and strike quite often.

Feeding

The main diet includes most small mammals and birds, but also frogs and lizards. Larger prey is struck and released, after which it is tracked down via its scent trail.

Reproduction

Breeds year-round. After mating, female keeps with developing embryos travel in and out of sunlight to keep them at a constant temperature. In equatorial regions, the gestation period is approximately 3-4 months, with an average of 60 young per litter. At birth the young are about 30 cm in length, more brightly colored than adults, and have yellow or beige tails.

Venom

These snakes are known to search for rodents in coffee and banana plantations. Workers there are often bitten by the snakes, which can lie camouflaged for hours, nearly undetectable, and striking with near-lightning speed.

They are much feared because the venom is particularly toxic and fast-acting. The fatality rate used to be high, but nowadays treatment is usually possible if the victim receives medical attention soon enough.^[9] Venom yield averages 124 mg, although it may be as much as 342 mg. The fatal dose in humans is just 62 mg.

The enzyme, Reptilase, derived from this snake's venom is used in modern medical laboratories to measure fibrinogen levels and to measure blood coagulation capability. The test is considered to be a replacement for Thrombin Time, and is used when heparin is present in the sample. The enzyme is unaffected by heparin.

Taxonomy

The taxonomy of this species is controversial; it may include the B. leucurus and the B. moojeni, and some of its populations are sometimes said to be separate species. The B. asper was formerly included in this species but most authorities now consider it distinct.

See also

• List of crotaline species and subspecies
• Bothrops by common name
• Bothrops by taxonomic synonyms
• Crotalinae by common name
• Crotalinae by taxonomic synonyms
• Snakebite

References

Further reading