Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
SubFamily: Crotalinae
Genus: Lachesis

Lachesis muta: The Bushmaster

The bushmaster is the largest viper in the world, and is classified as a pit viper (subfamily Crotalinae), because of the heat sensitive pits on its head. Its current classification is the work of Francois-Marie Daudin, an 18th Century French biologist. Lachesis was one of the fates in ancient Greek mythology, who determined the length of a person's life, and muta comes from a word meaning silent.

Bushmasters vary slightly depending on the area in which they originate, and this has given rise to a further classification into subspecies. Some herpetologists argue that these should be considered separate species.

  • Lachesis muta muta: South American bushmaster
  • Lachesis muta stenophrys: Central American bushmaster
  • Lachesis muta melanocephala: Black-Headed bushmaster, or Osa bushmaster

Physical characteristics
For a viper, the bushmaster is fairly slender, but compared to other venomous snakes of its length, such as the King Cobra it is heavily built. Normal adult length is about 9 feet, but the largest specimens can grow up to more than 12 feet long.

With a tan colouration, and dark rhomboidal patterning the bushmaster is well suited to its life as an ambushing predator of the forest floor.

Like other vipers the bushmaster has a large, triangular head that contains long fangs and large venom glands. While the drop-for-drop lethality of the bushmaster's haemotoxic venom is not as great as that of many other snakes the large volumes injected lead to a human fatality rate of near 80%.. Survivors are left with considerable scarring, and the bitten limb usually has to be amputated.

Range and Habitat
The Bushmaster can be found throughout much of southern Central America, and norther South America, but it is a rare snake, and infrequently encountered by humans.

The Bushmaster's preferred habitat is undisturbed lowland rainforest, and unlike other vipers it is intolerant of built-up areas, further leading to a decrease in the liklehood of human contact.

The Bushmaster feeds almost exclusively on small mammals throughout all periods of its life. These are killed, and the digestive process started when they are injected with the powerful venom delivered from the snake's fangs. Bushmasters catch most of their prey at night, when vision is impaired, but the heat sense provided by its heat pits is not. These heat pits are very sensitive, and able to detect temperature differences of a fraction of a degree. Bushmasters are not very fast and tend to catch most of their prey by ambush.

Reproduction and Growth
The Bushmaster is the only oviparous (egg-laying) viper in the Americas. All the other species, such as the rattlesnakes are viviparous (bear live young). Bushmasters tend to lay about a dozen eggs, which are guarded by the female until they hatch. Newly hatched Bushmasters are like small versions of their parents, and fully able to fend for themselves. The female does not protect them, and they are independent soon after birth.


  • Snake: Chris Mattison
  • Collins Gem Snake photoguide