The scientific name Lachesis muta means "silent fate" referring to their tail shaking, though they lack a rattle. Due in part to their large size, bushmasters produce much more venom than many other species of vipers. For comparison, a bushmaster produces eight times more venom than an American copperhead (Agkistrodon contortrix).
During mate seeking, courtship, and mating, bushmasters use chemical trails and tactile stimulation. Their forked tongues supply the vomeronasal organ, which connects with the accessory olfactory bulb in the brain. Like other vipers, they rattle their tails when threatened, but there are no actual rattles. Bushmasters also have paired pit organs on the face, between the eye and nostril (as do other pit vipers), to sense infrared energy (heat).
Communication Channels: visual ; tactile ; chemical
Other Communication Modes: scent marks ; vibrations
Perception Channels: visual ; infrared/heat ; tactile ; acoustic ; vibrations ; chemical
Bushmasters are listed as vulnerable under the Red List due to habitat destruction.
Bushmasters are oviparious, typically laying a clutch of 5 to 19 eggs. Bushmasters are the only egg-laying pit vipers in the New World. The females brood the eggs, which have an incubation period of roughly 60 to 79 days. The young hatch at approximately 30 to 50 cm with bright orange or yellow tail tips, used to lure prey; this color fades over time. They gain their adult coloring at 1 to 2 years old and reach sexual maturity at about 4 years old.
Bushmasters are of concern due to their venomous bites. Their venom attacks the circulatory system and can cause death without treatment. The cryptic nature and sit-and-wait predation habits of these snakes makes accidental envenomation a possibility. Bushmasters have been known to follow people for several meters, head held high, after being disturbed and may follow to attack. Bushmasters are greatly feared in some places.
Negative Impacts: injures humans (bites or stings, venomous )
Bushmasters, like many other snakes, help reduce rodent populations. In addition, bushmaster venom may offer possible applications for use in medical research and medicines.
Positive Impacts: source of medicine or drug ; research and education; controls pest population
Bushmasters are primary predators of a wide variety of small mammals and perhaps frogs and birds. They are probably preyed on by relatively few species. Bushmasters presumably are subject to various parasites and diseases, but there is little information in the literature.
Bushmasters are crepuscular or nocturnal predators that mostly eat small mammals, such as rodents, in the wild. Birds and reptiles may occasionally be eaten. Spiny rats (Proechimys species) are favored prey items in Costa Rica. Bushmasters are mainly ground-living, sit-and-wait predators; they conceal themselves near likely areas of rodent activity and wait for a prey animal to come within striking range.
Animal Foods: birds; mammals; amphibians; reptiles
Primary Diet: carnivore (Eats terrestrial vertebrates)
Lachesis muta is a viperid snake native to several Central American and South American countries. In Central America, bushmasters can be found in tropical forest areas of Panama, Costa Rica, and Nicaragua. In South America, their range consists of tropical areas of Brazil, Ecuador, eastern Peru, Bolivia, the Guianas, Colombia, Trinidad, and Venezuela.
At least three subspecies have been described are now considered full species by many authors (see Kohler 2003, Zamudio and Greene 1997, Ripa 1994). Lachesis stenophrys, the Central American bushmaster, occurs from southeastern Nicaragua to the Pacific coast of Columbia and Ecuador. Lachesis melanocephala, black-headed bushmaster, occurs in southeastern Costa Rica (Osa Peninsula and adjacent rain forest areas). Lachesis muta muta encompasses the remainder of the range in South America.
Biogeographic Regions: neotropical (Native )
Bushmasters primarily inhabit tropical moist forested areas. In addition, they live in habitats that receive plenty of precipitation, and maintain temperatures of 24 degrees Celsius or more. Due to this preference, bushmasters are only found at altitudes below 1000 m.
Range elevation: 1000 (high) m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: rainforest
Lifespan of wild individuals is unknown. Captive specimens generally live 12 to 18 years, though have been recorded to live up to 24 years.
Range lifespan
Status: captivity: 24 (high) years.
Typical lifespan
Status: captivity: 12 to 18 years.
Bushmasters are large snakes, with individuals often exceeding 2 meters in length, and with the potential to grow over 3.5 meters; these are the longest venomous snakes in the Americas and the second longest venomous snake in the world (after king cobras). The body ranges from reddish-brown, tan, or even a pinkish color, with very distinct dark, diamond-shaped markings down the back, often edged with yellowish coloring. They have light colored bellies and usually a dark stripe extending from the eye to the back corner of the mouth. The scales are heavily keeled above and there is typically a central vertebral ridge along the dorsum.
Range length: 2 to 3.6 m.
Other Physical Features: heterothermic ; venomous
Sexual Dimorphism: sexes alike
Young bushmasters are presumably subject to various predators, such as other snakes or raptors, but adults may have few predators other than humans.
Anti-predator Adaptations: cryptic
Bushmasters are solitary except during mating. Males find females by following a scent trail. During the courtship, a male will rub the female's head and flicks his tongue across the female's body. This can escalate to the male flipping himself upside down to rub his back on the female's and striking the female with his body. If successful, the pair can mate for over five hours.
Mating System: polygynous ; polygynandrous (promiscuous)
Females lays 5 to 19 eggs in a burrow, often an abandoned agouti burrow, and guard the nest. They do not eat during incubation and only leave the nest briefly to drink. Incubation requires 60 to 79 days. Newly hatched bushmasters are typically 30 to 50 cm long. Sexual maturity occurs at around 4 years of age.
Breeding season: Breeding occurs throughout the year.
Range number of offspring: 8 to 12.
Range gestation period: 60 to 78 days.
Average age at sexual or reproductive maturity (female): 4 years.
Range age at sexual or reproductive maturity (male): 3 to 4 years.
Key Reproductive Features: iteroparous ; year-round breeding ; sexual ; fertilization ; oviparous
Females guard their nests until the eggs hatch. Young are independent once they hatch.
Parental Investment: female parental care ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Female)
Lachesis muta, also known as the Southern American bushmaster or Atlantic bushmaster,[3] is a venomous pit viper species found in South America, as well as the island of Trinidad in the Caribbean. Two subspecies are currently recognized, including the nominate subspecies described here.[4]
Two additional subspecies, L. m. melanocephala and L. m. stenophrys, had earlier been recognized. However, both were elevated to species level by Zamudio and Green in 1997 (see L. melanocephala and L. stenophrys).[2]
Adults grow to an average of 2 to 2.5 m (6½-8 feet), although 3 m (10 feet) is not too unusual. The largest recorded specimen was 3.65 m (almost 12 feet) long, making the species the largest of all vipers and the longest venomous snake in the Western Hemisphere.[5] Lachesis muta is the third longest venomous snake in the world, exceeded in length only by the king cobra and the black mamba. Weight in this species is estimated at an average of 3 to 5 kg (6.6 to 11.0 lb), somewhat less than the heaviest rattlesnakes (like the eastern diamondback rattlesnake) or Bitis vipers (such as the Gaboon viper and rhinoceros viper).
The head is broad and distinct from the narrow neck. The snout is broadly rounded. There is no canthus. A pair of small internasals is present, separated by small scales. The supraoculars are narrow. Other parts of the crown are covered with very small scales. Laterally, the second supralabial forms the anterior border of the loreal pit, while the third is very large. The eye is separated from the supralabials by 4-5 rows of small scales.[6]
The body is cylindrical, tapered and moderately stout. Midbody there are 31-37 nonoblique rows of dorsal scales which are heavily keeled with bulbous tubercles and feebly imbricate. There are 200-230 ventral scales. The tail is short with 32-50 mainly paired subcaudals, followed by 13-17 rows of small spines and a terminal spine.[6] Like most New World pit vipers, Lachesis muta exhibits defensive tail vibration behavior in response to potential predatory threats[7]
The color pattern consists of a yellowish, reddish or grey-brown ground color, overlaid with a series of dark brown or black dorsal blotches that form lateral inverted triangles of the same color. The lateral pattern may be precisely or indistinctly defined, normally pale at the center.[5]
Some reports suggest that this species produces a large amount of venom that is weak compared to some other vipers.[8] Others, however, suggest that such conclusions are not accurate. These animals are badly affected by stress and rarely live long in captivity. This makes it difficult to obtain venom in useful quantities and good condition for study purposes. For example, Bolaños (1972) observed that venom yield from his specimens fell from 233 mg to 64 mg while they remained in his care. As the stress of being milked regularly has this effect on venom yield, it is reasoned that it may also affect venom toxicity. This may explain the disparity described by Hardy and Haad (1998) between the low laboratory toxicity of the venom and the high mortality rate of bite victims.[9]
Brown (1973) gives the following LD50 values for mice: 1.5 mg/kg IV, 1.6–6.2 mg/kg IP, 6.0 mg/kg SC. He also notes a venom yield of 200–411 mg.[10] The bushmaster's venom has proteolytic activity, which destroys and causes lesions in the tissue, anti-coagulant, which causes incoagulable blood, hemorrhagic and neurotoxic, that acts mainly on vagal stimulation. The symptoms are quite similar to those caused by Bothrops, at the site of the bite there is pain, edema, ecchymosis, skin necrosis, abscesses, vesicles and blisters. The main complications at the bite site include necrosis, compartment syndrome, secondary infections and functional deficit. The systemic effects are characterized by hypotension, dizziness, visual disturbances, bradycardia, abdominal pain, nausea, vomiting and diarrhea.[11] Other manifestations are also similar to Bothrops, including systemic hemorrhage and kidney failure.[12] In ilhéus, Bahia, Brazil, a 7-year-old boy was bitten when he left the house and stepped on one of these specimens, which then readily bit him; death was reported to have occurred approximately 15 minutes later. In 2005, in northwest Mato Grosso, a 5-year-old child also died, going into shock approximately 30 minutes after being bitten by a Lachesis muta and succumbing within 90 minutes.[13][14]
Lachesis is one of the three Fates in Greek mythology and was supposed to assign to man his term of life—something this species is certainly capable of doing. The species is similar in appearance to rattlesnakes and vibrates its tail vigorously when alarmed, but has no rattle and was therefore called mutus (later muta), which is Latin for "dumb" or "mute". However, when in the undergrowth, the tail actually makes quite a loud rustling noise.[15]
Known as the mapepire zanana or mapepire grande (pronounced ma-pa(y)-PEE za-Na-na or ma-pa(Y)-PEE GRAN-dey) in Trinidad,[16][17] surucucú in the Amazon Basin (surucucu in a large part of Brazil), shushúpe in Peru, and pucarara in Bolivia. In Venezuela the species is known as cuaima or cuaima piña. In Colombia it is known as verrugosa or verrugoso due to the warty look of its scales, and in Suriname as makasneki and makkaslang.[18]
It is called ĩtsãi in the Kwaza language of Rondônia, Brazil.[19]
In the Shawi language of Peru, it is called na’shi.[20]
L. muta is found in South America in the equatorial forests east of the Andes, and the island of Trinidad.[17] The type locality is "Surinami" (Suriname).[2] It occurs in primary and secondary forests; adjacent fields and cleared areas.[5] In Trinidad it tends to prefer hilly and mountainous regions.[21]
Bushmasters prey primarily on rats and mice. Birds and reptiles may occasionally be eaten. Spiny rats are favored prey items in Costa Rica.[22] Rice rats and agoutis are other favored prey.[23][24] Other prey items include porcupines, squirrels, opossums, squirrel monkeys, and frogs.[25]
Lachesis muta, also known as the Southern American bushmaster or Atlantic bushmaster, is a venomous pit viper species found in South America, as well as the island of Trinidad in the Caribbean. Two subspecies are currently recognized, including the nominate subspecies described here.
