Boas of the United States
The "giants" of the snake world, boids include the well known Boa Constrictor of the American tropics, which reaches the length of about 12 feet, and the Reticluated Python of southeastern Asia and Anaconda of South America, both capable of reaxhing lengths of over 30 feet. Most boids, like the two we have ni the United States, are significantly smaller. Of the 59 species belonging to 20 genera, the majority are found in tropical and subtopical regions of the world. Boids are the most prmitive of snakes. They have stout muscular bodies with short tails. Their back scales are smooth and relatively small and are sometimes irridescent and occur in numerous scale rows. By contrast, the underside scales are large and form transvers plates. Boid eyes have vertical pupils and many species posses temperature sensitive pits in the lip scales. Vestiges of hind limbs are present as spurs, usually visible on either side of the vent.
Boids occupy a variety of habitats. Many of the smaller species are burrowers, favoring loose or sandy soils. Large forms generally are terrestrial or semiaboreal. Pythons are egg layers and boas are live bearers. All boids feed on birds and mammals, which they suffocate in their constricting coils.
There are two species of Boids in the U.S.
Found from British Columbia to southern California and eastward to Montana, Wyoming and Utah.
Found from southern California into northern Baja California, southwester Arizona and adjacent Mexico.