Native to Mexico, Central America, and South America, boas are members of the family Boidae. All members of this family have certain characteristics that are different from the snakes in other families. For example, boas have vestigial hind limbs and fully functional left and right lungs.
Boas range in color from very light to very dark, with subspecies that thrive in the rain forest tending to be darker than those that thrive in the desert. They almost always have pale brown heads with one wide dark brown stripe at the back of the head that tapers into a fine line on the snout. Another wide stripe is generally located behind each eye, and there is a brown blotch in front of each eye.
Boas are ovoviviparous, which means they give birth to live young, and each litter averages between 30 and 50 young. Newborn boas are just over a foot long, but they will eventually grow to be 10 to 12 feet long.