Bothrops asper

Common names: terciopelo, fer-de-lance,^[2] (more).

Bothrops asper is a venomous pitviper species found in Central and northern South America.^[1] No subspecies are currently recognized.^[3]

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Description

These are among the most sexually dimorphic snakes. The two sexes are born the same size, but at the age of 7 to 12 months, females begin to grow faster than males. Males never reach 1.95 m long, while females average perhaps 1.85 m, and the greatest confirmed length is 2.5 m. Females have thick bodies, and big females may weigh 6 kg; heavier ones have been reported. Thus female terciopelos are among the heaviest venomous snakes. They also have heads two or three times as big as males in proportion to their size, and proportionally bigger fangs (typically 2.5 cm) as well.^[4]

The color pattern resembles that of B. atrox: diagonal stripes and diamonds of various shades of brown. The underside of the head is pale yellowish. Newborn snakes are brighter in color and males have yellow tail tips.

Common names

Terciopelo, fer-de-lance, barba amarilla (Guatemala), yellow-jaw tommygoff (Belize) mapepire (pronounced ma-pay-pee) balsain (Trinidad)^[5] The name fer-de-lance is commonly used in North America to refer to this species, as well as to B. atrox, despite the fact that the name has no legitimate origin and is not used in countries inhabited by this species.^[2]

The name terciopelo means velvet in Spanish.^[6]

Geographic range

Found in the Atlantic lowlands of eastern Mexico and Central America, including Guatemala, Belize, Honduras, Nicaragua Costa Rica and Panama. A disjunct population occurs in southeastern Chiapas (Mexico) and southwestern Guatemala. In northern South America it is found in Colombia and Venezuela. The type locality given is "Obispo, on the Isthmus of Darien" (Panama).^[1]

Another source describes the range as northwestern Mexico southward to Ecuador, including Belize, Colombia, Costa Rica, Guatemala, Honduras, Nicaragua, Panama, and its presence is questionable in Venezuela. It is also said that the species can be very common.^[4]

Habitat

It chiefly inhabits tropical rainforest and evergreen forest, but it also occurs in drier areas of tropical deciduous forest, thorn forest and pine savannah near lakes, rivers and streams.

Behavior

This species is mostly nocturnal, hiding in leaf litter or among roots during the day. They can strike from a coiled or uncoiled position. They usually flee from danger, but may turn abruptly and strike. During a strike, they may aim past their target to the side and quickly bring their head around to bite from behind.^[4]

Reproduction

Males generally stop eating for a time after the beginning of the reproductive cycle, while females stop after a few months of pregnancy. Mating occurs at different times of year in different areas. Gestation is typically 180 to 240 days, and young are born alive. The average litter is about 30, but litters up to 80 or 100 have been reported. Females need extra food after giving birth. Neonates use their tail tips to lure prey (caudal luring).^[4]

Venom

  This species is an important cause of snakebite within its range. Together with Crotalus durissus it is the leading cause of snakebite in Yucatán, Mexico. It is considered the most dangerous snake in Costa Rica, responsible for 46% of all bites and 30% of all hospitalized cases; before 1947 the fatality rate was 7%, but this has since declined to almost 0% (Bolaños, 1984). In the Colombian states of Antioquia and Chocó it causes 50-70% of all snakebites with a sequelae rate of 6% and a fatality rate of 5% (Otero et al., 1992). In the state of Lara, Venezuela, it is responsible for 78% of all envenomations and all snakebite fatalities (Dao-L., 1971). One of the reasons so many people are bitten is because of its association with human habitation and many bites actually occur indoors (Sasa & Vázquez, 2003). Well-known herpetologist Douglas March died after being bitten by this species.^[7]

This species is irritable, fast-moving and agile. It is also regarded as being more excitable and unpredictable than B. atrox, and has a reputation for being aggressive. Its large size and habit of raising its head high off the ground can result in bites above the knee. It has also been observed to eject venom over a distance of at least 6 feet (1.8 m) in fine jets from the tips of its fangs (Mole, 1924).^[7]

Bite symptoms include pain, oozing from the puncture wounds, local swelling that may increase for up to 36 hours, bruising that spreads from the bite site, blisters, numbness, mild fever, headache, bleeding from the nose and gums, hemoptysis, gastrointestinal bleeding, hematuria, hypotension, nausea, vomiting, impaired consciousness and tenderness of the spleen. In untreated cases, local necrosis frequently occurs and may require amputation. In 12 fatal cases the cause of death was septicemia (5), intercranial hemorrhage (3), acute renal failure with hyperkalemia and metabolic acidosis (2) and hemorrhagic shock (1).^[7]

Venom yield (dry weight) averages 458 mg with a maximum of 1530 mg (Bolaños, 1984)^[7] and an LD₅₀ in mice of 2.844 mg/kg IP.^[4]

Taxonomy

This species was formerly regarded as a subspecies of B. atrox and is still often confused with it.^[4]

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