Senses

Since snakes in the course of their history often lived underground, have developed their senses differently than most other animals. Because the eyes were trained not to sophisticated institutions, the vision of many species weak, especially grave species are almost blind. They compensate for this disadvantage by other sense organs, some of which are extremely powerful.


Eyes

 About 10 percent of all snakes are almost blind and can at best distinguish light and dark. This group includes virtually all types of the most primitive snake families Typhlopidae, Leptotyphlopidae and Anomalepidae underground and a small number of living species of other families. The eyes of the remaining species can be assigned according to their pupils form three groups: eyes with round, with horizontal and vertical pupils. Most snakes have eyes with round pupils. Snakes with small round pupils usually lead a hidden life and hunt either day or night. Snakes with large round pupils are usually active during the day and have a good vision, even if they find it difficult to clearly see objects at rest. They often stretch the head and neck in the air, to gain a better overview. All water snakes, the bush snakes, whip snakes and the wrath of snakes in North America, Europe and Asia belong to this last group.

Vertical pupils are found in tropical vipers and adders. These species are adapted to hunting in low light, bright light in her pupils drawn together to slits to protect the retina. Horizontal pupil occur only in a few ways: in the eight Asian tree snakes of the genus ahaetulla and in the two African viper species of bird Thelotornis. Standard as well as pupil size and location of the eyes allow these snakes a very good binocular vision, the snakes with the side of the eyes is missing. Binocular vision, the prerequisite for accurate distance estimation. This is important for species that use their bodies as a bridge between branches or their prey from leaves and branches, "pluck."

vertical pupils (Pazific Boa)

horizontal pupils (Whip Snake)

round pupils (Green grass snake)

Smell

Like other vertebrates also, snakes have noses that are associated with the smell centers of the brain. They also have a special organ, the Jacobson's organ. It consists of a paired indentation or two pockets in the mouth of the serpent, in which they can place the tips of their tongue gespalttenen. By stretch out her tongue and licks a few seconds it takes to scent molecules from the air. In the jacobson's organ, they are then analyzed and the information is passed to the brain. The snake will repeat this process until it knows what it's all at the smell is.


Listen

Although snakes have no external ears are still remnants of the inner ear structure in the form of a small bone, the columella, the availability of the vibrations transmitted to the inner ear. To perform vibration, then the lower jaw to be in contact with the ground. The vibrations are then transmitted through the jaw bone, the columella and the square leg to the inner ear. Besides the kicks and the rustle of potential enemies can snakes almost certainly too low Airborne sound carry.


Perception of heat

Certain snakes have unusual sensory organs called pit organs. They were from representatives of three families: the pythons and pit vipers. with pit organs that carry between the scales of the mouth edges in Phyton they lie in the mouth edge of pit vipers have shed themselves paired pits between eyes and nostrils are so called in some parts of Latin America "natrices cuatro" (four nostrils). In all species, the pit organs are designed with a layer of cells that contains a number of thermo-receptors, which are all connected to the brain. These cells can perceive snakes smallest temperature increases, as they are based on small warm-blooded animals, which are among their prey. (Even lizards, although in cold blood, emit little heat, because they can be heated by sunlight on her body temperature.) The pit organs allow snakes, temperature changes of only 0.2 ° C exercise. The pit organs are directed forward, and by analyzing the Wärmeinforrnationen the two sides of the head can tell the snake position and size of their prey. This means that they can even strike target in complete darkness. In experiments with a blind rattlesnake made this their prey in 98 percent of cases, while the hit rate to only 27 percent rate fell, as they covered their pit organs.