They don’t need it. But it does make them look nice.

Snakes don’t need UVB to process vitamin D3 and calcium the way most lizards do. But it can still help to process vitamins and calcium, which is a good thing.

Snakes, like many animals, do see in the UV spectrum. Theoretically this means they will eat better and be more active because their environment is more natural and interesting. I have a UV light on my parrots for this same reason, and it did make a noticeable difference in their behavior.

I have heard some people panic about UV exposure, cancer, sunburn, etc. Don’t worry, this won’t happen from a low watt UVB bulb. More is not always better, you can use something very basic with a snake.

A very cool video Exo Terra put out a while back:
http://www.facebook.com/video/video.php?v=123710844868