Can Snakes Smell?

As much as I hate snakes, biology swears I have two things in common with them. First, we both have pathetic eyesight. Second, our sense of smell, through the nose, leaves much to be desired. Sure, I can smell bacon sizzling, but outside of that and nearby paper mills, neither Serpentidae nor I am gearing up to compete on an upcoming episode of America’s Got Olfactory Talent. So, let’s get to the topic of the moment. Can snakes smell things in any meaningful way? If so, how? If I freshen up with some Tom Ford Hombré Leather, will every cottonmouth in the swamp, sorry, I mean scenic wetlands behind my house come slithering?

He Smelleth with Forked Tongue

Most, or maybe all (I’m not willing to get close enough to look), snakes have nostrils and a rudimentary sense of smell through similar equipment to ours. But, unlike dogs, detecting scents that way is not among their superpowers.

Snakes have a high olfactory gear known as the Jacobson’s (or vomeronasal) organ. Residing above the roof of their mouth, this organ has access to the inside of their mice holes through two small holes in their palette. Here’s where things get creepy.

You know how snakes flick their tongue, scaring the crap out of people with self-diagnosed ophidiophobia like me? That has a purpose—to collect molecules of scent-generating things. Yes, when you smell something foul, little pieces of it are going into your mouth and nose, but that’s a story for another day. Anyway, the tongue picks up some bits of smelly matter, and when the snake retracts it, the material makes its way to the Jacobson’s organ through those two little holes in the roof of its mouth. The Jacobson’s organ is much more finely tuned to detect scent. You might say snakes reach out and touch the surrounding air, getting an olfactory swab, then process the “smell” by rubbing it on the roof of their mouths. Kind of cool. Creepy but impressive.

Stereo Smell-O-Vision

Let’s add a unique biological twist. Just like our eyes and ears can detect stereo, snakes can smell in stereo, thereby getting a directional sense of where the odor is coming from. A snake’s tongue is forked, and as you’ll remember, two holes in the roof of its mouth lead to the Jacobson’s organ. Just as our eyes and ears process differing input signals, snakes process stronger or weaker scents from each side.

Since snakes flick their tongue around once per second, their little snake brains do an impressive job of figuring out the precise direction of the source of a scent. That’s how they catch nimble prey like small critters so effectively.

Put all this together, and snakes can do a bang-up job of tracking live buffet opportunities by smelling with their tongue.