Constrictors belong in the Boidae family. Essentially, there are two types of constrictors - boas and pythons and are among the worlds largest snakes. They can measure as long as 30 feet and weigh in excess of 300 pounds and can have as many as 400 sets of ribs.

Constrictors are non-venomous snakes but they do bite to hold onto their prey while they coil their massive bodies around it. They can swallow prey up to 5 times larger than the diameter of their mouths. After swallowing a meal, it can be as long as two years before it will need to feed again.

Constrictors are often the subject of horror movies. Their size (usually exaggerated) is immense and while they appear threatening, do not "hunt" for prey. They prefer to "ambush" their prey either at a water hole or by dropping on it from a tree.

The main difference between boas and pythons is that boas give birth to live young while the python lays eggs. Females incubate the eggs by coiling around the clutch and will generate a constant temperature by muscular contractions. The female is usually larger than the male.

Boas are mostly found in the Americas. The python is found in the tropical regions of Africa, Asia, Australia and the South Pacific Islands. They are both considered to be old world snakes. Unlike other snakes, members of the Boidae family have two functioning lungs rather than one.

Boas and pythons are susceptible to a disease called Inclusion Body Disease or IBD. The disease is a retrovirus as is AIDS. Popular thinking is that IBD is snake AIDS. The symptoms include lethargy, seizures, regurgitation, mouthrot, "star gazing", nervous system disorders and an inability to right themselves. There is no treatment or cure currently available. It is recommended that all infected animals be euthanized. The disease can be spread from snake to snake that are kept in the same enclosure.