Dolphins are mammals of the suborder of toothed whales. Dolphins live in the seas, rivers connected with the ocean, feed on molluscs, crustaceans. Currently, there are about 30 species of dolphins, among them the most popular: killer whale, dolphin, black dolphin, Ghanaian susuk. Dolphins reach speeds of up to 50 km / h in the water. Scientists are still unraveling the secrets of the energy-speed abilities of dolphins. We imagine dolphins jumping out of the water. Why do they do it? It used to be thought that these are the so-called breathing exercises. After all, dolphins don't have gills, but lungs. And when jumping, they gain more air. Canadian scientists have found that jumping also helps save energy.
The word dolphin goes back to the Greek δελφίς (delphis), which in turn comes from the Indo-European root * gʷelbh - "womb", "womb", "womb". The name of the animal can be interpreted as "newborn baby" (perhaps because of the external resemblance to an infant or because the cry of a dolphin is similar to that of a child).
In total, the dolphin family includes about 40 species. Of these, 11 species are found in the waters of Russia. Porpoises are often referred to as dolphins. Dolphins are also called species belonging to the superfamily of river dolphins.
By the way, the so-called Gray paradox is associated with dolphins, which has not yet been proven or refuted. In the 1930s. Englishman James Gray was surprised by the unusually high swimming speed of dolphins (37 km / h according to his measurements). Having made the necessary calculations, Gray showed that, according to the laws of hydrodynamics for bodies with unchanged surface properties, dolphins should have had several times greater muscle strength than was observed in them. Accordingly, he suggested that dolphins can control the streamlining of their bodies.
Dolphins have a powerful sonar that can detect an object the size of a sink at a distance of 15 meters. Thanks to this, they quickly find food, and even in turbid water. It is known that with the help of such orientation, dolphins' brain receives and processes hundreds, thousands of times more information than the human brain, processes information passing through the optic nerves.
By the way, dolphins do not sleep (they have to emerge from time to time for a new portion), but during rest they can turn off either the left or the right hemisphere (that is, the halves of the brain sleep in turn).
We all know that dolphins talk to each other. Previously, scientists paid attention to clicking and whistling sounds made by dolphins and easily perceived by human hearing. Then scientists got to sounds 10 times higher than the boundaries of human perception. The sound perception of people is in the frequency band up to 20 kHz, dolphins use the frequency up to 200 kHz. The sounds of this inaudible group of dolphins emit like a beam. Therefore, they are difficult to learn.
The brain of an adult dolphin weighs about 1700 grams, and that of a person - 1400. A dolphin has twice as many convolutions in the cerebral cortex than a human. According to the latest scientific data from cognitive ethology and zoopsychology, dolphins have a "vocabulary" of up to 14, 000 sound signals, which allows them to communicate with each other.
Dolphins are superior in training to dogs, monkeys, elephants and other animals. They are the only predators that do not attack humans (for comparison, more than a thousand people in the world die from the canines of "human friends" dogs a year). There are cases when dolphins rescued drowning people, and at the cost of their own lives they drove sharks away from people. What is the reason for such a humane (and more "human" than the attitude of people towards them) attitude towards people, we do not yet know. After all, dolphins have been studied by humans by 1%. Of the dolphins, bottlenose dolphins are more studied, they help fishermen, drive fish in nets, save drowning ones, protect divers from sharks, scout the seabed, guard top-secret military facilities, find sunken ships, etc.
Dolphin therapy is a psychotherapy method that is based on communication between humans and dolphins. It is carried out in the form of communication, play and simple joint exercises under the supervision of a specialist. It is often used in the treatment of diseases in children such as cerebral palsy, early childhood autism, attention deficit hyperactivity disorder, etc.
The United States and Russian law enforcement agencies have trained ocean dolphins for several tasks. Their training included: detecting underwater mines, rescuing sailors after the destruction of their ship, finding enemy combatants, and finding and destroying submarines as kamikaze.
On July 23, the world celebrates World Whale and Dolphin Day. This holiday was established in 1986, when the International Whaling Commission (IWC), after 200 years of merciless extermination, introduced a ban on whaling.