Boas

Boas are a large family of snakes that come in different sizes, patterns and lifestyles on most continents around the world except Australia and Antarctica. The largest boa is the green anaconda from South America. Most boas have heat-sensing pits on their head, which are used to find prey. They are nonvenomous and usually are constrictors, which means they wrap their body around their prey—a small animal—and tighten their muscles, which suffocates the prey so it can be swallowed whole.

Most boas live in trees or on land and give birth to live young, though a few lay eggs. Some male boas compete for females by wrestling with one another until the strongest snake wins or the female makes her choice.