A boa is a common name for nonvenomous constricting snakes. True boas belong to the family Boidae, with over 40 species. The name "boa" can also refer to Mascarene boas (family Bolyeriidae) and dwarf boas (family Tropidophiidae), though these aren't closely related to true boas. True boas are in the subfamilies Boinae and Erycinae. Boinae includes the boa constrictor, tree boas, and anacondas, found in the American tropics, Madagascar, and the southwestern Pacific. Erycinae includes sand boas and the West African earth python, found in Asia, India, and Africa. Boa constrictors, typically around 3 meters (10 feet) long, live from Argentina to northern Mexico. They are active at dusk and dawn, feeding on birds and mammals, killing by constriction. Pythons, found in Africa, Asia, and Australia, tend to be larger than boas. Boa constrictors bear live young, while pythons lay eggs.

Where do boas live in the wild?

Boa constrictors, belonging to the boa family Boidae, inhabit diverse environments from Argentina to northern Mexico. They thrive in tropical rainforests but also live in savannas, cane fields, and semiarid scrublands. Other true boas are found in the American tropics, Madagascar, and islands of the southwestern Pacific. The boa constrictor (Boa constrictor) occupies a variety of habitats from coastal northern Mexico and the Lesser Antilles to Argentina. Most species of the Boinae subfamily are terrestrial to strongly arboreal. The young often move from the trees to the ground as they get older and larger.

Boas are nonvenomous constricting snakes that include over 40 species of true boas. They are divided into two subfamilies: Boinae and Erycinae. Boas' prey depends on their habitat, size, and hunting strategy. Boas of the Boinae subfamily, such as the boa constrictor, eat birds and mammals, which they grasp with their bite before constricting. The boa constrictor eats a variety of birds and mammals. Meanwhile, boas of the Erycinae subfamily, such as the sand boa, typically feed on lizards and small mammals.

How do boas catch and kill their prey?

Boa constrictors are nonvenomous snakes that kill their prey by constriction. They coil around their prey, cutting off blood flow and causing organ failure within seconds. These snakes are largely terrestrial, but they will climb trees in search of birds. They feed on a wide variety of birds and mammals. Boas have special heat-sensitive organs that act as infrared receptors on their heads, which helps them to detect warm-blooded prey in the dark. When stimulated by a strong odor or vibration, a boa will rapidly flick its tongue in and out, transferring any odor particles adhering to the tongue to the Jacobson’s organ in the roof of its mouth.

How do boas differ from pythons?

Though both are large, muscular constrictors, pythons and boas differ in key traits. Pythons are generally larger, sometimes reaching 10 meters (33 feet), while boas usually reach about 3 meters (10 feet) but can grow longer. Pythons have heat-sensing pits between their lip scales to detect warm-blooded prey, a feature generally absent in boas. Pythons thrive in the tropics and subtropics of Africa, Asia, and Australia. Boas inhabit regions from northern Mexico to Argentina. Pythons lay eggs, often coiling around them to regulate temperature. Boas are ovoviviparous, incubating eggs inside their bodies and giving birth to live young.

What are some well-known species of boas?

Several well-known boa species exist, each with unique characteristics and habitats. The boa constrictor ( Boa constrictor ) is a large, thick-bodied snake found from Argentina to northern Mexico, commonly around 10 feet (3 meters) in length. The red-tailed boa ( Boa constrictor constrictor ) is a popular subspecies in the pet trade. Anacondas ( Eunectes ) are another well-known genus of boas from the American tropics. Green anacondas are among the largest snakes in the world, reaching up to 30 feet (9 meters). Other notable species include the emerald tree boa ( Corallus caninus ) of tropical South America, known for its green color and sizable teeth for catching birds, and the rainbow boa ( Epicrates cenchria ) of Costa Rica to Argentina, recognized for its iridescence.

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Introduction References & Edit History Quick Facts & Related Topics

Images

A bright green emerald tree boa (Corallus caninus) coiled around a branch in a dense Amazon rainforest, with large tree roots visible in the background.

Illustration of a boa constrictor (Boa constrictor constrictor) wrapped around a branch, showing its patterned brown and tan scales, with a scale bar indicating length in centimeters and inches.

Illustration of a boa constrictor (Constrictor constrictor), showing a large, coiled snake with a patterned brown, tan, and black scaly body wrapped around a tree branch.

At a Glance

boa summary

Quick Facts

Related Topics:: anaconda; Titanoboa; tree boa; Erycinae; Boinae

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A bright green emerald tree boa is coiled around a branch in a dense Amazon rainforest, with large tree roots visible in the background. — Emerald tree boa An emerald tree boa, native to the Amazon rainforest of South America.

boa

snake family

Also known as: Boidae, boid, true boa

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History

Top Questions

What is a boa?
A boa is a common name for nonvenomous constricting snakes. True boas belong to the family Boidae, with over 40 species. The name "boa" can also refer to Mascarene boas (family Bolyeriidae) and dwarf boas (family Tropidophiidae), though these aren't closely related to true boas.

True boas are in the subfamilies Boinae and Erycinae. Boinae includes the boa constrictor, tree boas, and anacondas, found in the American tropics, Madagascar, and the southwestern Pacific. Erycinae includes sand boas and the West African earth python, found in Asia, India, and Africa.

Boa constrictors, typically around 3 meters (10 feet) long, live from Argentina to northern Mexico. They are active at dusk and dawn, feeding on birds and mammals, killing by constriction. Pythons, found in Africa, Asia, and Australia, tend to be larger than boas. Boa constrictors bear live young, while pythons lay eggs.
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Where do boas live in the wild?
Boa constrictors, belonging to the boa family Boidae, inhabit diverse environments from Argentina to northern Mexico. They thrive in tropical rainforests but also live in savannas, cane fields, and semiarid scrublands. Other true boas are found in the American tropics, Madagascar, and islands of the southwestern Pacific.

The boa constrictor (Boa constrictor) occupies a variety of habitats from coastal northern Mexico and the Lesser Antilles to Argentina. Most species of the Boinae subfamily are terrestrial to strongly arboreal. The young often move from the trees to the ground as they get older and larger.
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What do boas eat?
Boas are nonvenomous constricting snakes that include over 40 species of true boas. They are divided into two subfamilies: Boinae and Erycinae. Boas' prey depends on their habitat, size, and hunting strategy.

Boas of the Boinae subfamily, such as the boa constrictor, eat birds and mammals, which they grasp with their bite before constricting. The boa constrictor eats a variety of birds and mammals. Meanwhile, boas of the Erycinae subfamily, such as the sand boa, typically feed on lizards and small mammals.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How do boas catch and kill their prey?
Boa constrictors are nonvenomous snakes that kill their prey by constriction. They coil around their prey, cutting off blood flow and causing organ failure within seconds.

These snakes are largely terrestrial, but they will climb trees in search of birds. They feed on a wide variety of birds and mammals. Boas have special heat-sensitive organs that act as infrared receptors on their heads, which helps them to detect warm-blooded prey in the dark. When stimulated by a strong odor or vibration, a boa will rapidly flick its tongue in and out, transferring any odor particles adhering to the tongue to the Jacobson’s organ in the roof of its mouth.
4 Britannica Sources
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How do boas differ from pythons?
Though both are large, muscular constrictors, pythons and boas differ in key traits. Pythons are generally larger, sometimes reaching 10 meters (33 feet), while boas usually reach about 3 meters (10 feet) but can grow longer. Pythons have heat-sensing pits between their lip scales to detect warm-blooded prey, a feature generally absent in boas. Pythons thrive in the tropics and subtropics of Africa, Asia, and Australia. Boas inhabit regions from northern Mexico to Argentina. Pythons lay eggs, often coiling around them to regulate temperature. Boas are ovoviviparous, incubating eggs inside their bodies and giving birth to live young.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What are some well-known species of boas?
Several well-known boa species exist, each with unique characteristics and habitats. The boa constrictor (Boa constrictor) is a large, thick-bodied snake found from Argentina to northern Mexico, commonly around 10 feet (3 meters) in length. The red-tailed boa (Boa constrictor constrictor) is a popular subspecies in the pet trade.

Anacondas (Eunectes) are another well-known genus of boas from the American tropics. Green anacondas are among the largest snakes in the world, reaching up to 30 feet (9 meters).

Other notable species include the emerald tree boa (Corallus caninus) of tropical South America, known for its green color and sizable teeth for catching birds, and the rainbow boa (Epicrates cenchria) of Costa Rica to Argentina, recognized for its iridescence.
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boa, common name for a variety of nonvenomous constricting snakes. There are more than 40 species of true boas (family Boidae). In addition, boa may also refer to two other groups of snakes: the Mascarene, or split-jawed, boas (family Bolyeriidae) and dwarf boas (ground and wood boas of the family Tropidophiidae); these two families are not closely related to each other or to the true boas.

Boa constrictorThe boa constrictor's name is derived from the manner in which it kills its prey, through constriction: first it grasps the prey, and then it uses its coils to exert a deadly amount of pressure. An adult boa constrictor is typically about typically about 3 metres (10 feet) long.

Rainbow boaDrawing of a rainbow boa (*Epicrates cenchria*).

Red-tailed boa constrictorRed-tailed boa constrictors (*Boa constrictor constrictor*) are native to Central and South America and are known for their distinctive reddish tail and powerful constricting abilities.

The true boas are divided into two subfamilies, Boinae and Erycinae. Boinae includes the boa constrictor (Boa constrictor), tree boas (genus Corallus), and anacondas (genus Eunectes) of the American tropics; two other genera are found on Madagascar and islands of the southwestern Pacific. Members of Boinae range from 1 metre (3.3 feet) long in some species to commonly more than 4 metres in the green anaconda. The boa constrictor occupies a variety of habitats from coastal northern Mexico and the Lesser Antilles to Argentina; though seldom more than 3.3 metres (11 feet) long, some have grown to more than 5 metres. One subspecies, the red-tailed boa (Boa constrictor constrictor), is particularly popular in the pet trade. Several tree boas possess sizable teeth used for catching birds. An example is the 1.8-metre (6-foot) emerald tree boa (Corallus caninus) of tropical South America; the adult is green above, with a white dorsal stripe and crossbars, and yellow below. The rainbow boa (Epicrates cenchria) of Costa Rica to Argentina is not strongly patterned but is markedly iridescent. Except for the anacondas, most boines are terrestrial to strongly arboreal. The young often move from the trees to the ground as they get older and larger. Most species have labial (lip) pits with heat-sensing organs that complement their sense of smell and excellent vision. Mammals and birds are common prey, which is usually captured by a bite-grasp followed by constriction.

Rubber boaRubber boa (*Charina bottae*).

Subfamily Erycinae includes 10 Asian, Indian, and African species of sand boa (genus Eryx) and the West African earth python (Charina reinhardtii), in addition to two North American species. Erycines are live-bearers (as opposed to egg layers) that have stout cylindrical bodies, blunt heads, and short tails. Most measure less than 70 cm (28 inches). These terrestrial snakes are often subterranean, and most live in arid and semiarid habitats, where they prey on lizards and small mammals. The brown, 45-cm (18-inch) rubber boa (Charina bottae) of western North America is the most northerly boa and is a burrower that looks and feels rubbery. The 90-cm (35-inch) rosy boa (Charina trivirgata), ranging from southern California and Arizona into Mexico, usually is brown- or pink-striped.

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Except for two egg-laying Asian species (genus Xenophidion), the 24 dwarf boas of family Tropidophiidae bear live young and live in the West Indies, Central America, and northern South America. They are predominantly terrestrial, occasionally foraging in low trees and bushes to hunt small vertebrates, especially amphibians and lizards.

The single surviving species of family Bolyeriidae (Casarea dussumieri) lives on Mauritius and Round Island. It is unique among snakes in that the lower jaw is hinged in the middle, which enables the snake to grasp hard-bodied skinks with a firm ratchetlike grip. It is a 0.8–1.4-metre-long egg layer. Bolyeria multocarinata was similar and went extinct owing to human introduction of rats and other predators.

One extinct relative of modern boas (Titanoboa cerrejonensis) lived between the end of the Cretaceous Period (some 65.5 million years ago) and the middle of the Eocene Epoch (about 40 million years ago). At the time it was the largest terrestrial vertebrate in the world. Known from a single fossilized vertebra, T. cerrejonensis probably weighed 1,135 kilograms (about 2,500 pounds) and reached a length of 13 metres (about 43 feet).

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by J.E. Luebering.

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