Yellow Rat Snake
For quite some time, I've strove for the perfect photo of a snake's flickering, forked tongue. This picture of a yellow rat snake is my best attempt so far.
I came across this snake while hiking on a cool spring morning in an oak forest. Presumably slowed by the chilly weather, it was leisurely wandering through the leaf litter, seemingly oblivious to my presence. Every few seconds, it would pause, and its tongue would dance wildly about.
The tongue flicks were very fast, just a blur to the naked eye. Hoping by chance to catch the tongue in a picturesque position, I took 87 shots of this snake. This photo, shot number 68, was the best of the lot.
What makes this photo work is the bright yellow leaf against which the fork is silhouetted. Several other shots captured the tongue with agreeable sharpness, but it was lost against a busy background of dark leaf clutter.
Of Snakes and Lions
There's a connection between this photo and my photo of a lion flehmening. In both cases, the animals are detecting odors using their sensitive vomeronasal organ.
The organ is similar in both species, but the lion and the snake evolved different mechanisms for delivering odorants to it. The lion transfers odor molecules from the environment to the organ by flehmening. The snake does so by flicking its tongue, then pressing the tip against the roof of its mouth, where ducts to the organ are located.