Colorado Desert Sidewinder II

I recently caught a Colorado Desert Sidewinder along Snow Creek Road, outside of Palm Springs, and kept it for two weeks, so I could display it while I taught a Reptile and Amphibians merit badge class. 

I got some good closeup pictures while it was in an aquarium. I returned it back out to Snow Creek Road and let it go in daylight (I caught it after dark) and got some more good pictures while it was in its natural habitat. Rather than add the pictures to my prior post on the Colorado Desert Sidwinder, I decided to do a version II. One of the distinguishing characteristics of the sidewinder is its horns, 

raised supraocular (enlarged) scales above its eyes, 

which probably "help shade the eyes or prevent sand drifting over them." 

It is sometimes called the horned rattlesnake.  

A feature I found fascinating while looking at closeup photographs is the black "pepper" spots sprinkled over the scales, 

including the eye scale (known as the brille scale), which protects the eye. 

The spots help the snake blend into its environment. 

Note how well it blends into the sand. 

and

and

I also enjoyed the contrast of the pupils from the snake inside, where the pupils are enlarged, 

to outside in the sunlight where the pupils are just tiny slits and cross-shaped, 

contracted to reduce the amount of light entering into the eye. Unfortunately, when I let the snake go I was not treated to a display of its peculiar locomotion which gives it its common name (I have seen it at night). As it travels roughly diagonally (rather than sideways as the name suggests) across sand there are only small segments of the snake connecting to the ground at any particular time. The rest of the snake is lifted off the ground. The reduced friction allows it to move faster and it also helps protect the snake from the ground which can get very hot. Finally, the sidewinder has a very small rattle 

and it sounds more like the buzz of a wind-up child's toy. I've found that they tend to rattle less than most other rattlesnakes and are also less prone to wind up into the coiled defensive stance 

(this was the first time I've seen that behavior and it only happened after I prodded the snake).