What are dolphins like?

The clever dolphin is a small toothed whale. There are about 60 kinds of dolphins. Except for a few who live in fresh water, most of them live in the ocean. Common dolphins are bottlenose dolphins, true dolphins, porpoises and Malay dolphins. Dolphins can swim 20 ~ 30 nautical miles per hour with a top speed of 40 ~ 50 nautical miles per hour, which is unmatched by ordinary ships. Dolphins also like to live in groups and often swim in groups. Their team number is as high as more than 5000 people, in a long queue of thousands of meters. Dolphins are experts in swimming very fast, except for their special body structure and developed muscles. More importantly, it has smooth and elastic skin that does not touch water. Its skin can be divided into upper and lower layers. When subjected to water pressure, the outer layer will fluctuate with the distribution of water pressure and become uneven. It's like a foam pad being pressed by a person's body, some places are concave and some places are convex. When dolphins swim at high speed, the turbulence generated by body vibration will flow into the concave layer of the skin, so that the whole water flow near dolphins can keep regular laminar flow, thus greatly reducing the water resistance. According to this principle, some experts have developed an artificial dolphin skin and stuck it on the torpedo model, and carried out a water flow experiment at a speed of 70 kilometers per hour. Results The resistance of torpedo model was 60% less than that of ordinary model.

According to research, dolphins also have a very sensitive and accurate sonar system, which can detect high-frequency signals of 2000 ~ 200000Hz, and have excellent echolocation skills. It can make a sound, change the tone at will, and eliminate the interference of various noises; It can use the mandible to receive the echo, send it to the ear, analyze and judge the echo, and finally make a correct judgment on the target. Dolphins send out signals every ten minutes in order to detect the surrounding environment. Once the situation is abnormal, it will immediately send out continuous signals and quickly determine the orientation, distance and nature of the target, and take corresponding measures.

According to expert research, dolphins are smarter than orangutans and monkeys. For example, to control the current switch, dolphins only need 20 trainings to turn it off, while monkeys need hundreds or even thousands of trainings to learn. Once a dolphin was trained only five times. Dolphin is so smart because it has a developed brain. Dolphin's brain is not only big, but also has many grooves, like walnut kernel. The average brain weight of adult dolphins is 1.6 kg, that of humans is about 1.5 kg, and that of orangutans is less than 0.5 kg. In terms of absolute weight, the dolphin's brain is heavier than the human brain, but in terms of brain weight and weight ratio, human beings still rank first. The human brain accounts for 2. 1% of the body weight. The ratio of dolphin brain to body weight is 1. 17%, and orangutans only account for 0.7%. This shows that dolphins have much more brain tissue to control unit weight than orangutans. In addition, dolphins have some special skills. For example, when sleeping, the left and right hemispheres of the brain can take turns to rest. When the left hemisphere is in a state of inhibition, the right hemisphere is in an excited state, rotating once every ten minutes.

Since 1988, with the help of eight dolphins, the Florida Dolphin Research Center in the United States has enabled more than a dozen children with learning disabilities to overcome the language barrier and began to treat hundreds of children with cerebral palsy and mental injury.

In the late 1950s, a research institute was established in the United States, specializing in underwater activities and operations using marine animals such as dolphins. In the mid-1960s, the US Navy established a marine animal research and test base. 1964, Cage, a dolphin trained by the US Navy, made a voyage test with instruments. 1965, the United States trained another dolphin, Tafei, to search for the cockpit of astronauts who returned from space and fell into the sea, so as to protect the drowning personnel from sharks. During the Vietnam War, six dolphins and 1 1 dolphin trainers trained by the U.S. Navy Underwater Training Center participated in the patrol and vigilance of Cam Ranh Bay in Vietnam. This dolphin is equipped with a radio transmitter. One day, when it found the invading frogman, the dolphin quickly returned to the surface weapon platform on board. A cone suitable for the nose of dolphins is installed on the stage, and the top of the cone is equipped with measuring instruments and hollow needles. The poisoned dolphin immediately returned to the water to attack the frogman, injured the frogman with a needle and killed him immediately. Sometimes trainers will tie sharp edges to dolphins' fins and noses to train dolphins to cut off divers' air supply pipes and masks. Dolphins are also very good at deep-sea salvage. 1965, when the U.S. military tested the "Aslock" anti-submarine rocket and the "Lion Star" cruise missile, it installed acoustic beacons on the rocket warheads and missile launchers. As a result, the dolphins quickly found the "Aslock" anti-submarine rocket warhead and the "Tiens" missile launcher that fell into the 60-meter sea.

1987, during the Gulf War, the United States called five dolphins into the sea to ensure the safety of American ships anchored and cruising in this sea area. These five "underwater special forces" guarded around the formation day and night, effectively preventing the Iraqi frogman from attacking, and at the same time assisting the minesweepers in searching for a large number of mines. In order to destroy enemy ships, the US Navy also conducted bomb and mine tests on dolphins, fixed explosives or mines on the dorsal fin of dolphins, buried explosives in the belly of dolphins, or pulled dolphins by surgery and triggered mines to hit the target, thus achieving the purpose of destroying the target.

199 1 year, while the United States sent minesweepers to the Persian Gulf, it also sent a well-trained dolphin force to the Gulf to carry out mine detection and underwater combat missions: Iraq once organized a group of daredevils to attack American ships from underwater, but the American ships were closely protected by dolphins, and dolphins formed a strict defense line around them. They rely on sensitive sensing to guard against intruders. Once the enemy is found, Iraqi frogmen can't get close to American ships because of the protection of dolphin troops. Dolphins also protect their frogmen from sea snakes. If American navy frogmen or sailors are in danger at sea, they will immediately go to the rescue. In the war, the multinational forces used the help of dolphins to avoid the weakness of some equipment and reduce the losses caused by it. According to US Navy intelligence personnel, during the war, dolphins found mines in the Gulf at least seven times, and immediately sent a signal to inform the ship so that the ship could avoid mines in time.

Dolphins not only play an important role in the military, but also have important economic value: dolphin meat has high nutritional value and can be eaten; Dolphin subcutaneous fat is very thick, from which a large amount of dolphin oil can be extracted, which is an important raw material for leather, chemical industry, rubber, machinery and other industries. Its head and jaw can extract advanced lubricating oil for precision instruments such as aircraft instruments.