Fer-de-lance, Barba amarilla, Mapepire balsain
The Common lancehead is a highly venomous pit viper species found in South America. Its color pattern is highly variable, including a ground color that may be olive, brown, tan, gray, yellow, or (rarely) rusty. The body pattern typically consists of a series of dorsolateral blotches, rectangular or trapezoidal in shape, which extend from the first scale row to the middle of the back. These blotches may oppose or alternate across the midline, often fusing to form bands. The belly may be white, cream, or yellowish-gray, with an increasing amount of gray to black mottling posteriorly that may fade again under the tail. The head usually does not have any markings other than a moderately wide postocular stripe that runs from behind the eye back to the angle of the mouth. The iris is gold or bronze in color, with varying amounts of black reticulation, while the tongue is black.
Common lanceheads are found in South America east of the Andes, including southeastern Colombia, southern and eastern Venezuela, the island of Trinidad, Guyana, Suriname, French Guiana, eastern Ecuador, eastern Peru, Panama, northern Bolivia, and the northern half of Brazil. These snakes live in tropical wet forests and may also visit plantations in search of prey.
Common lanceheads are generally solitary creatures and prefer to be on their own. They are mainly terrestrial but are excellent swimmers and even climb trees when necessary to reach prey. These snakes are nocturnal and typically remain inactive throughout the day hiding under fallen logs, at the base of trees, below leaf-litter, or in dense vegetation. However, if necessary, they may forage at any time of the day. Common lanceheads hunt their prey using several techniques. They may use the sit-and-wait technique relying on their camouflage and suddenly attack prey that passes by or may actively forage searching on soil or among leaf litter. Common lanceheads are easily agitated. When threatened they prefer to rely on their camouflage hoping to stay undetected but may also flee, shake their tail against the leaf litter, or even attack.
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 strike with high speed.
Their venom is hemorrhagic, damaging the vascular endothelium and consuming coagulation factors in a mechanism known as “venom-induced consumption coagulopathy”. As a result, clotting assays such as prothrombin time and aPTT will be highly disturbed. Spontaneous recovery from coagulopathy is seen 14 to 30 hours after bite according to a study performed in French Guiana. A Mexican polyvalent antivenom was tested but had no effect on it. Bothrops atrox venom can result in several systemic and local symptoms, such as severe bleeding, kidney failure, abnormal clotting, blisters and necrosis. The bite can also result in hemorrhage in the central nervous system, which leads to sequelae and even death. In a case reported in the Brazilian Amazon, symptoms such as pain and ecchymoses, headaches, nausea, vomiting, diarrhea, hypertension and blood incoagulability were reported, the patient died of stroke, even after administration of the antivenom. The Common lancehead has an LD50 of 1.1 to 4.9 mg/kg, the venom of juveniles is more inflammatory, lethal, hemorrhagic and kills more quickly than that of adults, people bitten by neonates are more likely to develop coagulopathy.
Venom yield averages 124 milligrams (1.91 gr), although it may be as much as 342 milligrams (5.28 gr). The enzyme reptilase (batroxobin), derived from this snake's venom, is used in modern medical laboratories to measure fibrinogen levels and 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.
Common lanceheads are carnivores and eat mostly small mammals and birds, but also frogs, lizards, and tarantulas.
Common lanceheads breed year-round and give birth to live young. After mating, gravid females with developing embryos travel in and out of sunlight to keep themselves and the embryos at a constant temperature. In equatorial regions, the gestation period lasts about 3 to 4 months, and the litter consists of 60-80 young. At birth, the snakelets are about 30 cm (12 in) in total length, more brightly colored than adults, and have yellow or beige tails. They are born venomous and are extremely dangerous right after birth.
Common lanceheads are among the most numerous and common of pit vipers and are not endangered at present.
The Common lancehead population number is unavailable at present from open sources and its conservation status has not been evaluated.
