Originally Posted by cyccommute

The “pits” in pit vipers are in front of the jaw. They are located on the head between the eyes and the nostrils and are slightly smaller than the eyes. They are heat sensing organs.

The shape of the head is the give away. Pit vipers tend to have heart shaped heads which are wider at the back of the head where it attaches to the neck. Constrictors which are often confused for rattle snakes have a longer, narrower head. Here in Colorado we have three kinds of rattlesnakes…the prairie rattlesnake, the Western rattlesnake and the massasauga rattlesnake. They all have similar patterns on their skin.

You can see the different head shapes in these two snakes. This one is a prairie rattler. Not the very wide jaw


This is a bull snake. Similar skin pattern but the head is longer and less wide at the back. Bull snakes here also have a wonderful mimic ability. They will coil just like a rattlesnake…you can see the similar position of both snakes. They also shake the end of their tail and make a hissing sound that is unnervingly like the rattle of a rattle snake. It’s a very effective defense mechanism. They will also strike like a rattlesnake…personal experience…and their teeth are abrasive but they haven’t got fangs.



The rattlesnake is the one that I spooked in my post above. I left him alone. The bull snake below was on a bicycle path in Denver. I shooed it off the path so that it would get run over. He hissed and shook his tail at me the whole time. Still unnerving.