As snakes shed their skin as they grow. The old stiff skin is discarded and the new elastic skin allows the snake to grow larger. Check out this web site
http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/CGARTER/SHEDDING.HTM.

Snakes produce their own poison in special glands where it is stored until they release it when they bite something. Some snakes can even spit their venom at a victim. There are very few poisonous snakes and most are shy of humans. There are many poisonous snakes in the world but only four types are native to the US. They are the rattlesnakes, the copperhead, the cottonmouth and the coral snake

Hi snake fans,

As you know, not all snakes are poisonous.Some kill their prey by constriction (what's constriction?) Others just bite without venom. The ones that are poisonous have one of two main types of poison. One type is a neurotoxin, which basically stops your nerves from working. Some of the nerves that stop working are the ones that tell the lungs to work. The other type of toxin is called "proteolytic". This word means protein breakdown. This type of toxin "dissolves" flesh. Both kinds of toxin are made by the snakes' salivary glands. (What's saliva?)

Perhaps long ago no snakes were poisonous, they killed by biting. In one or two snakes mutations (mistakes) in the recipes for making the normal chemicals in saliva were harmful to the prey that a snake bit. Snakes with "killer saliva" did better than their neighbors with regular saliva and left more babies. The babies inherited the new recipe from their parents. Some of their descendants had new mutations in their "saliva recipes". Snakes with mistakes that made saliva harmless didn't do very well. Snakes with mistakes that made saliva more deadly did a lot better and left more babies. Over millions of years, some snakes got to be very deadly.

Snakes are covered with dry scales. This allows them to live in very wet and very dry climates because water doesn't leak in or out of them. Unfortunately, the scales don't grow, so a snake has to shed its old skin. This also allows snakes to replace the worn out scales. The scales are made of keratin. What parts of you are made of keratin?

Check out this page for great information on many kinds of animals, including snakes: http://www.oit.itd.umich.edu/projects/ADW/

I hope you enjoy your study of herpetology.