animalnewsblog.com

California ground squirrels have a unique defense against rattlesnakes; they can heat their tails and wave them at the snakes in order to intimidate them.  Since the tails are warmer than normal, the rattlesnake goes on the defensive, and no longer sees the squirrel as food.  Rattlesnakes, which are a type of pit viper, have a highy evolved organ that senses infrared heat.  The organs are much more sensitive than the heat sensors in boas and pythons, thus able to detect the variation in the tail temperature and core body temperature of the squirrel.  While it is unclear as to the physiologic mechanism by which the squirrel heats its tail, it appears to be voluntary to the point that the defense is used selectively against rattlesnakes.  Snakes without heat sensing capabilities do not elicit the defense response.  It goes to show that animal behavior and physiology is even more complex than we can imagine.