The Curious Senses of Snakes

Thanks to their peculiar senses, these reptiles are very precise in their actions. Most of them aren't dangerous to humans; they usually only attack when threatened or are stepped on unintentionally.
The Curious Senses of Snakes
Eugenio Fernández Suárez

Written and verified by the vet Eugenio Fernández Suárez.

Last update: 27 December, 2022

Sight, hearing and smell are some of the senses that contribute to the image we have of the world, but ophidians have a special way of processing the information that surrounds them. Let’s find out more about the incredible senses of snakes.

The senses of snakes: hearing

Snakes can dislocate their jaws and swallow large animals such as buffalo; this is because their bones are not fused in the same way as mammals. However, one disadvantage they do have is that their hearing is less developed than some other animals.

Ophidians lack an external ear and eardrum, and for a long time zoologists believed they were deaf. But the truth is that they possess a bone known as the columella auris, which is similar to the stirrup in the middle ear of mammals. The columella auris is wrapped in tissue and connected to the fluid of the inner ear, so it transmits vibrations.

Snakes are quite insensitive to sounds transmitted through the air, but their specialized senses can better detect vibrations in the ground.

Snakes’ whole bodies can sense the footsteps of prey and other such movements thanks to an acute sense of touch, especially if they rest their lower jaw on the ground, as this is in direct contact with the columella auris. In ophidians, their senses of touch and hearing work together to detect vibrations with extreme accuracy.

The senses of snakes: sight

Snakes’ eyes are very similar to those of other vertebrates, although snakes have transparent eye shields instead of eyelids, which molt along with their skin.

Some snakes, such as subterranean snakes, have primitive eyes that can’t detect colors. Despite this, most snakes, especially diurnal snakes, have round pupils with cones and rods, the cells responsible for distinguishing detail, light, and color.

Remember that snakes spend their lives close to the ground, with many visual barriers in front of them. That’s why a powerful sense of sight, such as that of birds of prey, is of no use to these reptiles.

Snakes’ secret weapon: heat

Their ability to detect infrared light is what makes some snakes true experts in detecting prey. Snakes like rattlesnakes, pythons and boas can detect thermal variations of as little as 0.001 degrees thanks to their thermoreceptor pits.

An infrared selfie.

Venomous snakes, such as rattlesnakes, have sense organs known as pits on both sides of their snout, similar to their nostrils, while some constrictor snakes such as pythons and boas have labial pits; they have more than rattlesnakes but they’re less sensitive.

This allows snakes with thermoreceptive abilities to detect and hunt prey in complete darkness. This is why it’s not enough to remain still and stop emitting vibrations in order to escape these snakes; although their eyesight isn’t as sharp, their heat detection is infallible.

The senses of snakes: smell

Snakes’ sense of smell is also very impressive; they have an organ known as the vomeronasal organ, also called Jacobson’s organ. Many animals have this organ, including humans, although some scientists believe it doesn’t work.

What this organ does is to capture pheromones and other chemical compounds; many of these can’t be captured by the regular sense of smell. These compounds must come into direct contact with the tissue of Jacobson’s organ in order to be detected; the snake uses its tongue to transport them there.

This is why you sometimes see snakes stick out their forked tongue to taste the air. Some believe that the forked shape of their tongue allows snakes to better determine the direction of chemical stimuli that reach their vomeronasal organ.

Although snakes also possess a regular sense of smell, their olfactory system is much less developed than that of other animals. To compensate for this, the vomeronasal organ allows them to track prey and even recognize their relatives.

In conclusion, although snakes’ traditional senses aren’t particularly sharp, their ability to detect heat, chemicals and vibrations makes them perfect hunters.

It’s important to note that most snakes aren’t dangerous to humans. They tend to flee as soon as they detect our huge vibrations, and will only attack us if they have no other choice. That’s why snake attacks usually occur by accident, such as when we step on them.

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