Friday, July 1, 2011

Aging Rattlesnakes: Don't Bother Counting Their Rattles


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            Taking care to step around clumps of wiregrass as you make your way through the pine forest, you suddenly hear it.  The sound is unmistakable. Working your way around the exposed roots of a large oak, you hear it from the base of the tree. Your blood chills as you instinctually freeze. 
          
  A rattlesnake’s rattle is an incredible thing, if you think about it. Take a run of the mill serpent, then add an odd-looking structure on the tail that makes noise, and you’ve got a rattlesnake. If we weren’t so used to the image of them, I’m sure we would think they were quite the strange creature indeed.
         
        A big rattlesnake with a long rattle is an impressive animal (assuming a hog hasn't eaten it), one persistent myth suggests the older the rattlesnake, the more rattles it has (although the entire structure is called a rattle , it is made up multiple rattles ).  In fact, so goes the myth, you can determine the age of the rattlesnake by simply counting its rattles.
         
            Not quite.

            Unlike mammals like us, who shed skin constantly in small pieces, snakes do it all in one shot. As a snake grows, they periodically need to shed their old skin to accommodate their larger body. When it’s time, a shedding snake will try to snag a piece of their old skin on a tree branch or rock and slither out of it. For most snakes, that’s that. But for rattlesnakes, each time an old skin is shed, a new rattle is added.
           
           If rattlesnakes always shed their skin once, and only once, a year, you might actually be able to tell how old a rattlesnake was by counting the rattles, but they don’t. Very young snakes grow quickly, some shed for their first time just a couple weeks after being born. 

        A newborn rattlesnake doesn’t have a functioning rattle, the characteristic sound is created when multiple rattles vibrate against each other and baby snakes are born with only a little nub at the end of their tail, called a button (or prebutton). In their first year of life however, snakes may shed their skin multiple times, adding a new rattle each time. 

          As snakes mature, their growth rates slow, to the point that some older snakes may not even shed once over the course of a year. Furthermore, as you might expect from a delicate structure on the back of a big snake in the wild, rattles can break off (close inspection can reveal whether this has occurred).
           
          So, if a given rattlesnake has seven rattles, the only thing you can say with certainty is that it has shed its skin at least seven times. This may not be terribly exciting news to people.

Rattlesnakes are impressive animals and their namesake rattles make them unique within the animal kingdom, the least we should do is get the facts straight about them.