Venomous? Nonvenomous? Whats the difference?

I think it is important for people to know the difference between a venomous and non-venomous snake. So here are some basic facts. This is what I was taught while working at The Brazos valley Museum of Natural History in Bryan.

1) Snakes aren't poisonous they are venomous. There is a difference and it is in the definition.

A poison is absorbed through the skin or ingested

A venom is injected.

So if the a snake injects a poison in to your skin through a bite it is venomous.

2) A nonvenomous snake can still bite you.

It may not be deadly but a nonvenomous snake still has teeth. ANYTHING WITH TEETH CAN BITE YOU!

3) Venomous snakes and non venomous snake (in Texas at least) differ in 4 ways.

• eye shape 
• head shape
• bite patten
• venomous snakes leave 2 bite marks 
• non venomous snakes leave a round bite mark with many teeth
• anal plates

Here is great identification chart from Maryland Department of Natural Resources Website (http://www.dnr.state.md.us/wildlife/Plants_Wildlife/vsnakes.asp) that demonstrates these differences:

non-venomous snake

1. Round pupils
2. No sensing pit
3. Head slightly wider than neck
4. Divided anal plate
5. Double row of scales on the underside of the tail
   
   
   The Indigo is an excellent example of these rules
   
   
   
   The Nonvenomous East Indigo Snake has a round head with round eyes
   
   
   
   

venomous snake

1. Elliptical pupils (like a cat)
2. Sensing pit between eye and nostril (pit vipers)
3. Head is triangular and is much wider than neck
4. Single anal plate
5. Single scales on the underside of the tail
   
   

  *In Texas we have an exception to these rules with the Coral snake. The coral snake has a round head with round pupils but IS venomous. It can be mistaken for a young corn snake if you don't know the difference in color, At the museum I teach the kids a simple rhyme:

Red on Black, friend of Jack

corn snake (nonvenomous) 

Red on yellow, KILL a fellow

coral snake (venomous)

But remember when you find a snake out in the wild (whether its venomous or non venomous) don't touch or kill it. Just leave it be. Snakes are a natural  form pest control and good to have around. If its in your house please call pest control.