Snakes: Feeling Sounds And Tasting Smells

Snakes sense the world in very different ways than humans do. But what do I mean by feeling sounds and tasting smells?

The Five Six Senses

Touch

A snake's sense of touch is highly developed. What else would you expect from an animal that does everything on its belly? Despite being covered in scales, snakes are highly sensitive to touch and can sense very slight vibrations through the ground. A snake will feel your presence long before it sees you.

Hearing

"But snakes don't have ears!" someone exclaims. But that is only partially true.

Snakes do not have external ears. External ears would be too cumbersome for a snake (especially since it's theorized that snakes evolved out of the necessity to become more efficient burrowers, and what better way than to get rid of those obtrusive and unwieldy limbs?) They do, however, have inner ears that allow them to hear low-frequency sounds that vibrate through the air. What about all those non-low-frequency sounds?

All the vibrations that a snake feels from the ground are transmitted through its body and to the quadrate bone, which connects the jaw to the skull. The quadrate connects to the middle ear, which is connected to the inner ear. Thus, due to a snake's sense of touch, its sense of hearing is highly acute.

Taste and Smell

When a snake quickly moves its tongue in and out of its mouth, it picks up various particles from the air and surrounding objects and can therefore taste the things around it. When a snake breathes air flows in and out of its nostrils, but it doesn't smell a thing. That is because snakes don't smell with their noses. They smell with their tongues.

The vomeronasal organ, more commonly known as the Jacobson's organ, is the sensory organ dealing with smells. It is present in most animals and is found at the base of the nasal cavity. In snakes, the receptors of the organ are located at the roof of the mouth. The particles collected by the tongue from the air or surrounding objects are transferred to the organ when the tongue retracts.

A forked tongue allows the snake to determine in which direction the tastes and smells are coming from.

Sight

The sense of sight is highly varied in snakes. Vision ranges from nearly blind to very keen eyesight. The level of development of a snake's vision is generally dependent on the snake's lifestyle.

Fossorial snakes spend the majority of their time in the dark. They don't require good vision. Their other senses are so well developed that the snakes can find food and detect dangers without seeing. Many of these snakes can only sense the difference between light and dark.

The best vision is found in arboreal snakes. Some snakes have binocular vision, which means that they can focus both eyes on the same object. Because arboreal snakes can live high in the trees, they can use their acute vision to locate potential prey or predators from far away. Good eyesight is especially useful when catching birds that are flying by.

For other snakes, vision is generally adequate. Most of these snakes live on the ground where there are often obstacles to obscure vision, making keen eyesight relatively useless. They lack the ability to sharply focus their eyes, so vision is usually movement-based.

Snakes don't have moveable eyelids. But there is a protective transparent lens that covers the eye. The loss of moveable eyelids may have been an evolutionary modification to help deal with the difficulties of a fossorial or aquatic lifestyle. Because of this modification, it is difficult to tell if a snake is sleeping or if it's just sitting still.

Infrared

Many snakes within the families Boidae and Viperidae have infrared-sensitive pits. Also known as heat pits, they can sense the heat radiating from animals and objects surrounding them. So far, research has determined that a snake's heat pits can sense heat as far as 30 feet away and are sensitive enough to detect temperature changes of less than .001 degree Celsius.

Herpetologists originally thought that infrared-sensitive pits evolved in some snakes to modify and improve hunting methods. Recent observation has shown, though, that the primary function of the pits is in thermoregulation. The snakes can determine which objects around them have been warmed enough by the sun or have been cooled enough in the shade and can then regulate their body accordingly. Detecting prey is a secondary function.

Next Time

Snakes use all of their senses to help them find food. In my next blog entry I will discuss how snakes hunt and eat.

Thanks for reading!

Other Blog Entries:

New Animal Attractions

Reptiles: A Scaly Introduction

Snakes: They're All Around

Snakes: A Family Affair (Part 1)

Snakes: A Family Affair (Part 2)

Snakes: Clever And Deadly Behaviors

Snakes: Do The Locomotion (Part 1)

Snakes: Do The Locomotion (Part 2)

Snakes: A Look Inside

Snakes: Feeding Time! (Part 1)