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Snake Anatomy & Physiology
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Holly Frisby, DVM, MS
Veterinary Services Department, Drs. Foster & Smith, Inc.

Sense Organs

The sense organs of snakes are uniquely different than those of mammals and other animals. Unlike mammals, which mainly rely on their sight and hearing, snakes rely primarily on their senses of smell and touch. They do not have moveable eyelids, but transparent caps called "brille" as protective eye coverings. Because of this, their eye movement is fairly limited. They also do not have an external ear, middle ear, or tympanic membrane (eardrum). Instead, they use a small ossicle (ear bone), called the "columella," to detect vibrations of sound waves conducted through the ground. They are able to pick up some sound waves conducted through the air, but only at very low frequencies.

Snakes also smell in a very different way than mammals. Mammals bring air particles into contact with the olfactory (smelling) nerves by breathing them into the nasal cavities through the nostrils. Snakes have both nostrils and nasal cavities, but they are not used to smell. Instead, the flicking tongue is actually a smelling device. There is a small organ on the roof of the oral cavity called the "vomeronasal organ", or "Jacobson's organ." The forked tongue is used to bring minute air particles into contact with this organ, and the snake then perceives and identifies the smell as prey, predator, or otherwise. So, unlike mammals, the tongue is not used to taste or aid in swallowing, but simply as an accessory smelling organ.

Some snakes also have a "sixth sense" that mammals and even other reptiles cannot boast. Vipers, rattlesnakes, and other members of the family of snakes known as the 'pit vipers' have special pits located between their eyes and nostrils. The pits are used to sense minute temperature changes as infrared rays, as an aid in locating warm-blooded prey such as rodents. A pit has two chambers. The interior chamber is naturally the internal temperature of the snake itself. The exterior chamber heats up when it is close to a heat source, and the snake is then able to detect the temperature difference between the two chambers. This system is so accurate that pit vipers are actually able to detect temperature changes as little as 0.002° Celsius.


Snakes, like all reptiles, are covered in scales that protect them from abrasion or dehydration. The scales on the top and sides of the snake are smaller and thinner than those found on the belly side. The thick, large scales on the belly are called "scutes," and they help to protect and support the tissues that are in contact with the ground. The scales can be very colorful and organized into interesting patterns. Unlike most other animals, there is no way to tell a male from a female based on color, as they will almost always look the same externally.

Though snakes are often described as being "slimy," their skin is actually very dry, In fact, they only have two skin glands — a pair of anal scent glands that secrete a substance used to attract a mate, provide protection from predators, and mark territory. Unlike other animals, snakes continue to grow until the day they die. Consequently, snakes periodically shed their skin in a process called "ecdysis." Before shedding the skin, the snake takes on a slightly bluish hue and the eyes appear cloudy. This is caused by fluid located between the layers of skin. Mites, malnutrition, and trauma, among other things, may cause dysecdysis, or abnormal shedding.

Snake Facts

The type of teeth a snake has can differ depending on the method used to capture and kill prey. There are three kinds of snake dentition:

  • Constrictor
  • Groove fanged
  • Hollow fanged

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Pictures: DCI |
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