Animal ears

How are the ears of animals? It turns out that the question is not so simple... Why, in order to better hear, the dog guards ears, and the horse anxiously drives with its ears? Of course, large movable ears play an enormous role in animals. Even champions of sound perception among birds - owls and owls were forced to acquire a special structure of feathers and down that mimics the auricle.

How are the ears of animals? It turns out that the question is not so simple...

To improve the perception of sounds coming from a certain direction, the ears of mammals have the shape of a funnel. In cats, dogs, horses, antelopes and in many other animals, ears are very mobile, they can turn towards the source of sound, catching very weak sounds. The outer ears of animals perform one more task - they amplify the sound. The auricle is a resonator. If the sound frequency is close to the resonator's own frequency of vibration, the air pressure in the auditory canal acting on the tympanic membrane increases in comparison with the pressure of the sound wave falling on the external ear.

In humans, the ears are relatively fixed. But inside the auricles there are cartilaginous tubercles - they hold back the sound. And in different ways, depending on which side it comes from. This allows the brain to accurately determine the source of sound.

And how are the ears of sea animals-whales and dolphins-arranged? At the bottlenose dolphin, on each side of the head, one can see by a tiny hole with a diameter of 1-2 mm. These holes are not symmetrical: one of them is much closer to the nose than the other. They are the beginning of the auditory canal. It is interesting that almost immediately after the external aperture it sharply narrows and takes the form of a tiny little crack with a 360x36 micron opening. But that's not all! Comparatively close to the exit, the auditory canal is completely overgrown, turning into a thin cord from a fairly dense tissue!.. How then do dolphins hear?

The point is that sound waves can propagate in any substance. The denser the environment in which sound propagates, the greater its speed and less energy is lost. Only at the boundary between the two media, the losses are enormous - only part of the sound waves penetrates into the new medium, the other is reflected from its surface. That is why the outer ear of terrestrial animals has the shape of a funnel filled with air. On the air cone, a sound wave without losses gets to the tympanic membrane. Many head tissues perform a great sound. The air waveguide leading to the middle ear is necessary only because the transition of sound waves from the air into the skin is difficult. Water animals are another matter. Skin and fat of dolphins on acoustic characteristics are close to water. Therefore, the transition of sound waves from water to the head tissue occurs without significant losses. That is why the outer ear with a special waveguide channel dolphin is absolutely not necessary.

In addition to trapping sound waves, the ears of animals, especially in the tropics, work as cooling devices. Many medium-sized desert animals have large ears. The difference is especially noticeable in comparison with their relatives from the temperate or northern regions of the planet. For example, desert chanterelles of feneca and eared hedgehogs have simply unreasonably great ears. And the red-haired hare has ears incomparably longer than our hare or hare. Even bigger is the ears of another African oblique - the cow hare. All these creatures with water are especially economical. They can not afford to cool the body by evaporation of water. How are the inhabitants of the deserts saved from the heat?

Radiation exchange makes it possible to easily get rid of excessive heat, and the ears of desert animals perform the function of radiators. Here, it turns out, why the ears of animals are long.