Rattlesnake – Part 1

As a child I was enthralled with reptiles, mesmerized by the unending stare of a snake and the myriad geometric patterns and colors of turtle and lizard scales. I would spend hours trekking through nearby fields and streams in search of all things slimy and scaly- a habit I never grew out of. Growing up in the Midwest, species of the western US up until now were encountered only as pictures in books and childhood daydreams. After relocating to the west coast, much of my free-time is spent in the field attempting to catch a glimpse of the native reptile and amphibian species of central California. More recently, I have become interested in identifying and untangling the seemingly unfathomable number of bird species found here on the Central Coast. As I encounter local species of reptiles, amphibians and birds I will be posting pictures of these animal encounters along with interesting natural history facts about each specimen. There is so much beauty within the world to be discovered and appreciated; why not start in one’s own backyard.

Rattlesnakes belong to a subfamily of vipers known as Pit Vipers – I want you to look closely at his face; notice that, just to the side of his eyes, there are two large holes. These are what give “Pit Vipers” their name. These “pits” are actually sensory organs capable of detecting even the most minute of changes in temperature. They are, essentially, infrared cameras that allow the pit viper to “see” the body heat map of it’s prey. Let’s take a look at how they work!


The mechanism of how these pits work is complex and a bit tricky to explain. The best way to think of these pits are as little “heat eyes”: The pits themselves are are composed of a thin, suspended membrane (think of a structure similar to your eardrum) that has a surface that is very, very sensitive to temperature. This surface essentially “sees” different temperature wavelengths and constructs a thermal image based on all of the temperatures in range, similar to the image seen here. Interestingly, these pits are also found in other types of snakes, including some species of pythons and boas!

There are three hypothesized advantages to snakes that have these pits: The first is rather obvious based on the picture; the snake can locate its prey much easier! Similarly, predatory animals will also be “seen” with greater accuracy, helping the snake to avoid them, if possible. Finally, snakes, like all reptiles, are cold blooded. This means that snakes must regulate their body temperature in accordance with the external temperature. If a pit viper, for example, is feeling too hot, it can simply “see” where the cooler area is and move there!