Physics in the animal world: dolphins and echolocation

Dolphins are marine mammals. Their body is designed specifically for the lifestyle of these animals. Most sense organs of dolphins do not work in the same way as in terrestrial mammals. Their brains are no less complex than the human brain, and dolphins have developed longer than humans (about 25 million years). Scientists have been studying dolphins for many decades, but there are still questions about their lifestyle, to which there is no answer. Among other issues - the communication system of these animals. Experts believe that they have their own language, but people are not able to decipher it.

In order to do this, scientists are trying to study the acoustic system of dolphins, as well as their "echo sounder" - a system for transmitting sound signals. Underwater visibility is almost always severely limited, so dolphins do not rely on vision (they are well developed, but you cannot call it ideal), but on hearing. Dolphins use high frequency sounds to communicate with each other. For orientation in space, these animals make clicks of a certain frequency and duration. These sound signals, reflected from objects, give the dolphin information about the objects surrounding it.

Many terrestrial mammals have a very keen sense of smell. Dolphins, having chosen the aquatic environment for life, almost lost their sense of smell. Instead, they have learned to perfectly use the sense of taste. Taste buds give dolphins an idea of ​​the presence of certain substances in the water, which may indicate the proximity of food, danger, or relatives. Scientists believe that dolphins can detect even a very small difference in salinity. For this reason, those dolphins that live in the Mediterranean Sea almost never enter the waters of the Black Sea, where the salinity of the water is about 17, which is half the salinity of the water of the Mediterranean.
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Dolphins are best developed for hearing, they are of paramount importance in their lives, replacing in most cases vision. In search of food, these mammals are immersed in great depth, where visibility is almost absent. Even if the dolphin’s vision were well developed, it’s still difficult to see something. But echolocation allows you to detect food and perfectly navigate the surrounding space. At the same time, at the beginning of the last century, experts argued that the hearing of dolphins was very poorly developed.

Voice machine

Like all other mammals, among the ancestors of dolphins, the vocal apparatus was most likely associated with the respiratory system. But in dolphins and their relatives, the voice system is not connected with the lungs. Their mouth serves only to grab items, including food. The respiratory system of dolphins is complex, the point of inhalation and exhalation is a breathing point, which is located at the top of the head. Three pairs of air bags are connected to the respiratory passage of dolphins at once. Scientists believe that these bags play an important role in the generation of sounds by dolphins. They communicate by closing the mouth and breathing, under water, and not on the surface.

In September of this year, researchers from the Karadag Nature Reserve published a paper showing the communication system of these animals. Changing the volume and frequency of clicks, bottlenose dolphins make up words, and of them - sentences. According to experts, in many respects these conversations are similar to human speech. Taking part in the conversation, the dolphins listen carefully to each other. When one dolphin "speaks", the second listens to him, and vice versa. “Each sound generated by one of the animals is different from the other sound generated by the interlocutor. The difference is in the spectrum and frequency of the pulsations. At the same time a number of combinations of sounds is not repeated. We can assume that each pulsation is a separate phoneme or a word from the language of dolphins, ”says study leader Vyacheslav Ryabov. The speed of the pulsation of dolphins is about 700 pulses per second.


The clicks themselves are generated in a specific system, which is located under the breath in the upper part of the head. Sound waves are sent by animals directionally, this possibility provides a fatty layer on the forehead of the animal, as well as the concave front surface of the skull. As a result, the dolphin is able to collect sound in the directional "beam" with a divergence angle of 9 °. This gives animals ample opportunity. Bottlenose dolphins, for example, can detect small objects the size of a mandarin at a distance of over 100 meters.

Hearing aid

The organ of hearing in dolphins is no less complex than the sound apparatus. It is clear that they have no auricles, although the ancestors of dolphins had them. If this organ were to remain with dolphins, it would cause foci of turbulence during movement, which would be the cause of the generation of a strong noise that muffles all other sounds for the animal.

Therefore, the sounds are perceived by dolphins in a different way. First, the sound signals pass through the external ear aperture (it is still there). Then, along the same narrow auditory canal, the acoustic wave reaches the middle ear. Moreover, the middle and inner ear are placed in these animals not in the cranial bone, but separately, connecting with the skull using a special tendon attachment. The sonic nerve transmits the received signals to the brain. Interestingly, the sound receivers for the left and right ears are independent of each other. This allows the animal to locate the source of the sound. For example, the same bottlenose dolphin can accurately localize the place where a small fish falls, and immediately swim to the site of the fall. In addition to the ear canals, dolphins get sound and using the lower jaw, where the bone plate is located with a thickness of 0.3 mm. It plays the role of the membrane.

Due to the structure of its auditory system, dolphins can perceive a wide range of sounds - from 1 hertz to 320 kilohertz. This is a much wider sound range than one that a person can perceive.



Generating sounds and catching their reflection from surrounding objects, dolphins study the surrounding space. Moreover, the dolphin's echolocation "device" is very reliable. Dolphins find each other at a distance of over 150 meters in total darkness. In this case, they generate ultrasonic signals with a frequency of 60-90 kilohertz. With the help of its “locator”, the dolphin receives data not only about the distance to obstacles and objects, but also about their nature (size, shape and material properties).