The Western hooknose snake (Gyalopion canum) is a species of small colubrid snake native to the United States, from western Texas to southeastern Arizona, and into northern and central Mexico. It was once classified in the genus Ficimia, but was reclassified due to distinct morphological characteristics. It is sometimes referred to as the Chihuahuan hook-nosed snake because it is commonly found in the Chihuahuan Desert.
The Western hooknose snake is a small species, growing to 18-28 cm (7-11 inches) long. They are gray or gray brown in color, with 25-48 dark brown or black blotches down their back, and a cream colored underside. They have a slightly upturned snout, which gives them their common name.
Hooknose snakes are nocturnal burrowers, most often found under rocks. They prefer slightly sandy habitats, near a permanent water source. Their diet consists primarily of spiders and centipedes. They are oviparous.
One of its primary defensive behaviors is to make a popping noise with its cloaca, i.e., farting. According to an article in the August, 2000 issue of Discover magazine, during a laboratory experiment carried out by Bruce Young, a morphologist at Lafayette College, the snakes only farted when they felt threatened, and some farted so energetically that they lifted themselves off the ground. 
Gyalopion canum is quick in short bursts or spurts.
- ↑ Smith, Hobart M. and Edmund D. Brodie, Jr. 1982. Reptiles of North America: A Guide to Field Identification. Golden Press. New York.