Boa (Boidae)

The term ‘boa’ has almost become synonymous with the majestic boa constrictor or common boa. But in truth, it is just one species in a whole family of equally captivating snakes. Boas are a group of non-venomous snakes belonging to the family Boidae, also known as Boids. They include some of the world’s most renowned and easily recognizable snakes. Though most are native to the Americas, boas are also found in Europe, Africa, Asia, and various Pacific Island countries.

Many of these snakes have become cherished exotic pets thanks to their calm temperament and captivating appearance.

The family Tropidophiidae, or Dwarf Boas, has 20-30 species, almost all of which are referred to as ‘dwarf boas.’ However, this article deals only with the Boidae family.

Characteristics That Define Boas

All members of the Boa family share the following typical characteristics that set them apart from most other snakes.

1. Being non-venomous constrictors: All boas are non-venomous and kill their prey through constriction. Once a boa catches its prey, it wraps around the prey’s body to cut off its air supply and kill it. Though constrictor snakes exist in other families, the Pythonidae or Python is the only family other than Boa, where all members are constrictors.
2. Presence of heat-sensing pits: They are one of the three groups of snakes with heat-sensing pits on their faces (the other two are pythons and pit vipers). These pits enable them to detect infrared thermal radiation and catch warm-blooded prey.
3. Presence of vestigial limbs: All snakes in this family have rudimentary pelvic girdles with small vestigial hind limbs that look like small spurs on either side of the cloaca or vent. These spurs are more prominent in males. Again, the only other family that displays similar rudimentary limbs is Pythonidae.
4. Two functional lungs: Although most snakes usually have only the right lung, with the left being vestigial (in certain colubrids, elapids, and vipers) or completely absent, boas (and pythons) typically retain the primitive characteristic of having two functional lungs. The left lung is significantly smaller, but it can still reach up to 75% of the size of the right lung in certain species.
5. Lack of postfrontal bones and premaxillary teeth: No species in this family has the postfrontal bone in their skull. Neither do they have premaxillary teeth in their upper jaw. Both these are important anatomical features that differentiate them from pythons.
6. Giving birth to live young: Most boas are either ovoviviparous or viviparous, meaning they give birth to live young instead of laying eggs. While other snake families also exhibit this trait, boas are the only constrictor family that gives birth to live young, as pythons are oviparous (egg-laying).

How Big Do They Get

Although boas are often depicted as giant snakes in movies and video games, the family actually includes a diverse range of species. These range from the Abaco Island boa, which is less than a foot long, to the green anaconda, the largest snake on Earth, reaching lengths of up to 30 feet.

Common Types of Boas

In the pet trade, the Boa constrictor constrictor (BCC) and the Boa constrictor imperator (BCI) are the most sought-after, with their manageable size and gentle disposition. Others, like the rosy and rubber boas, are almost as famous among reptile enthusiasts.

Here are the most recognizable types of boas, including those found in the wild and those commonly kept as pets:

Name	Avg. Adult Length	Avg. Adult Weight	Characteristic Physical Features	Average Lifespan	Native Range	Habitat
Large Boas
Green Anaconda (Eunectes murinus)	15-30 feet	150-200 pounds	Thick and muscular olive green body with black blotches.	Wild: 10-15 years Captivity: 10-20 years	South America (the Amazon and Orinoco basins)	Predominantly aquatic, found in swamps, marshes, and slow-moving rivers in rainforests.
Cuban Boa (Chilabothrus angulifer)	10-13 feet	30-40 pounds	Dark brown to black with lighter bands.	Wild: 20-30 years Captivity: Over 30 years	Cuba	Tropical and subtropical forests, often in limestone caves and hollow trees.
Red-tailed Boa/Boa Constrictor/BCC (Boa constrictor constrictor)	6-12 feet	30-50 pounds	Distinctive red tail with dark saddles.	Wild: 20-30 years Captivity: 25-40 years	Northern South America	Tropical rainforests, savannas, and agricultural areas.
Argentine Boa (Boa constrictor occidentalis)	7-10 feet	20-30 pounds	Black or dark brown saddles on a lighter background.	Wild: 20-30 years Captivity: 25-40 years	Northwestern Argentina, Paraguay	Dry, subtropical forests and semi-arid regions.
Madagascar Ground Boa (Acrantophis madagascariensis)	8-10 feet	15-20 pounds	Brown or reddish coloration adorned with black and white oval patches.	Wild: 10-20 years Captivity: 15-20 years	Northern, central, and western Madagascar	Dry forests, scrublands, and rocky areas.
Central American Boa/BCI (Boa imperator)	4-8 feet	10-20 pounds	Similar to the Boa constrictor, but often darker and smaller.	Wild: 20-30 years Captivity: 25-40 years	Central America	Range of habitats from tropical rainforests to arid regions.
Amazon Tree Boa (Corallus hortulana)	5-7 feet	2-3 pounds	Color may vary greatly, but the head often has dark stripes extending from the eyes.	Wild: 15-20 years Captivity: 20-25 years	Amazon Basin	Trees and bushes near rivers and streams.
Rainbow Boa (Epicrates cenchria)	5-7 feet	3-5 pounds	Reddish-brown color with black markings and an Iridescent sheen	Wild: 10-15 years Captivity: 15-20 years	Central and South America	Humid tropical forests and wetlands.
Emerald Tree Boa (Corallus caninus)	4-6 feet	3-5 pounds	Bright green with white or yellow markings along the spine.	Wild: 10-15 years Captivity: 15-20 years	Northern South America	The canopy of tropical rainforests, often near water sources.
Mexican West Coast Boa (Boa sigma)	4-8 feet	3-5 pounds	Light brown to tan body with darker brown saddles.	Wild: 20-30 years Captivity: 30-40 years	Western Mexico along its Pacific Coast	Semi-arid, tropical, and coastal areas, in dry forests, thorn scrub, and rocky terrain.
Duméril’s Boa (Acrantophis dumerili)	6-8 feet	10-20 pounds	Earth-toned gray-brown colors with complex dark patches.	Wild: 10-15 years Captivity: 10-20 years	Western and southwestern Madagascar	Dry forests and scrublands.
Hispaniolan Boa (Chilabothrus striatus)	6-9 feet	10-20 pounds	Brown or gray with darker stripes.	Wild: 10-20 years Captivity: 15-20 years	Hispaniola	Tropical and subtropical forests, often in karst landscapes with limestone caves.
Small Boas
Solomon Island Ground Boa (Candoia paulsoni)	2-4 feet	1-2 pounds	Color varies from browns to grays and greens, with keeled scales and darker markings.	Wild: 10-15 years Captivity: 15-20 years	Solomon Islands, Papua New Guinea	Tropical forests and woodlands.
Rough-scaled Sand Boa (Eryx conicus)	2-3 feet	0.5-1 pound	Rough, keeled scales; light brown or tan color with dark brown or black markings.	Wild: 10-15 years Captivity: 15-30 years	South Asia	Arid and semi-arid regions with sandy or rocky soil.
Rosy Boa/Desert Rosy Boa (Lichanura trivirgata)	2-4 feet	1-2 pounds	Gray to brown, with three distinct longitudinal stripes running down the body.	Wild: 15-20 years Captivity: 20-30 years	Southwestern United States (Mojave Desert) and northwestern Mexico (Baja California, Sonora)	Arid and semi-arid environments such as deserts and rocky hillsides.
Arabian Sand Boa (Eryx jayakari)	1-2 feet	0.1-0.3 pounds	Yellowish-brown with dark brown markings; shovel-shaped snout, and eyes on top of their head.	Wild: 10-15 years Captivity: 15-20 years	Arabian Peninsula	Arid desert environments with loose, sandy soil.
Kenyan Sand Boa (Eryx colubrinus)	1.5-2.5 feet	0.3-1 pound	Stout, smooth body with orange and brown markings and a keeled tail.	Wild: 10-15 years Captivity: 15-20 years	Eastern Africa	Arid and semi-arid regions with loose, sandy soil.

Note that the red-tailed boa (BCC) and the Central American boa (BCI) are well-known for their striking physical resemblance. This similarity can be particularly challenging for new or prospective pet owners, as both species are popular in the pet trade.

Both these snakes were previously recognized as subspecies of the Boa constrictor. However, the Central American boa is now recognized as a separate species, Boa imperator. Despite this reclassification, it retains the name BCI, which originates from its old scientific name as a subspecies of Boa constrictor, Boa constrictor imperator.

Feeding Habits

Being constrictors, boas can eat any small to medium prey they can coil themselves around. Their diet in the wild usually includes lizards, birds, rodents, and other small mammals. Large species, like the Boa constrictor and Cuban boa, can eat larger animals like bats, pigs, mongoose, and rabbits in addition to birds and other lizards. The green anaconda is known to catch even larger prey, including young tapirs. They swallow their prey whole, which can then take days or even weeks to digest.

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