Crew members who often go out to sea often find such a situation: there is a group of animals around the hull following it, jumping and playing while swimming, this animal is not large, it is 2~3 meters long, but the swimming speed is not slow, it is the little brother of the cetacean family - smart dolphins.
Dolphin, shaped like a fish, the mouth is thin and long, the upper and lower jaws have 46~66 pointed teeth, the body is thin and long, generally about 2~2.4 meters long. On the back of the streamlined body, there is a sickle-shaped dorsal fin. The back is grey-black , the belly is white , and a pair of pectoral fins grow near the head on the abdomen. The weight is between 100~200 kg. Don't look at its long snout, there are so many teeth in its mouth, but it can't chew food, just feed on small fish, shrimp, squid, etc.
Dolphins live in warm offshore waters and are found almost everywhere in warm waters. They prefer to live in groups, ranging from a group of more than 10 dolphins to a maximum of hundreds. They do not have a fixed estrus mating season. When the male dolphin finds a favorite couple, he will follow the female dolphin for a long time, gradually approaching during the roaming, and then rubbing each other with his pectoral fins until the other party signals that he accepts the love, and then enters the mating stage. The gestation period of dolphins is about 9 months, and only one cub is born in one litter, but the cubs are amazing, their body length is about half that of adult dolphins, but their weight is only one-sixth to one-seventh of adult dolphins. After the cub is born, it is accompanied by its mother. The mother lies on her side in the water while breastfeeding, and the pups are sucking milk close to their mother. The newly born pups are breastfed once an hour in less than an hour, but soon they are fed only a few times a day, and the lactation period is about a year. Because dolphins are social animals, dolphins that become mothers often adopt a "duty system" to protect their cubs, that is, one dolphin who is a mother takes care of a group of cubs at a time, and the rest of the mothers go to distant places to feed.
The dolphin's brain is well developed, its brain weight accounts for 1.2% of its body weight, and it is a highly intelligent marine animal. It has a large brain surface area and complex sulcus. Some experts believe that its intelligence exceeds that of apes, and one of the important reasons is that the brain capacity of dolphins is greater than that of apes. Trained dolphins can learn the skills of ringing bells, throwing balls, blowing horns and drilling fire rings in a relatively short time. It has been recorded that dolphins not only imitate the sounds of cats and dogs, but also utter some simple English words. These abilities of dolphins stem from its developed brain.
Dolphins are gentle, sensitive, playful, curious and sociable animals. We talked earlier that dolphins are social animals. In a community, if a dolphin is injured, its companions will take care of it. When their partner is killed, an accomplice immediately swims up to lift the injured partner up and give the companion a chance to breathe fresh air. It is said that there was a sick dolphin that was "transported" by its companions for four consecutive days until it regained its ability to breathe, and for nearly half a month, along with its kind, it also took turns on duty from time to time, lifting it out of the water to breathe until it fully recovered and could swim freely on the surface to breathe.
The kindness of dolphins is not only manifested in saving their kind, they have also rescued humans many times. In the history of modern navigation, they have been recorded many times to rescue the victims of human beings. In 1972, dolphins swam more than 100 nautical miles to rescue a woman who fell into the water to shore. There was even a time when the ship sank, the passengers fell into the sea, just when there were sharks near the person who fell into the sea, and a group of dolphins happened to swim past the place where the passengers fell into the water, and the dolphins split into two, one part fought the shark, and the other protected the person who fell into the water. According to zoologists' research, the rescue behavior of dolphins is an instinctive manifestation: companions are in trouble, and groups are rescued; When encountering natural predators, such as sharks and orcas, they rise up and fight hard. It is more instinctive to push objects out of the water, and when it encounters wooden blocks, steam pads, etc. in the sea, it will also push it out of the water.
Dolphins also sometimes love to play turtle games. They often swim under the turtle in groups, push the turtle to the surface with a pointed and hard snout, and then flip the turtle over so that it faces the sky on its back.
Sometimes a group of dolphins jump out of the water at the same time, press the turtle together, press it several meters underwater, and before the turtle recovers calm, several dolphins come to tease the turtle to play. The turtle had no choice but to shrink its head and limbs into its shell. The dolphin made such a joke, but he swam away quickly.
Dolphins have the ability to emit and receive ultrasonic waves. With this ability, they can accurately determine the location of obstacles or prey; be able to relate to one's own kind; During courtship, male dolphins can also use this to connect with female companions who have lost contact. The ultrasound emitted by dolphins, as experts have determined, is between 250 hertz and 200 kilohertz, with an extremely wide frequency range. When emitting sound waves, the air bags of the head emit sounds of different frequencies, and the two angled air bags of the front jaw are emitted in different directions with the swing of the head. When receiving ultrasound, there is a division of labor, the ear receives low-frequency sound waves, and the jaw receives high-frequency sound waves. It is precisely because of its superb ability to transmit and receive ultrasonic waves, so it will not encounter obstacles when swimming at high speed in the ocean. Its ability to avoid collisions makes it often able to navigate for sea ships, so that sea ships avoid hitting the rocks. It is recorded that in the offshore waters of New Zealand, there is a reef dense area, in this area, there was a white dolphin, starting in 1871, for 40 consecutive years to guide the sea ship, until old death, it can really be described as "bowing down, after death".
We call dolphins "friends of man" not only because they have rescued people in distress at sea, faithfully carried out navigation missions for sea vessels, but also because of their friendly fellowship with humans. According to records, dolphins like music, especially the sound of the lyre, and when someone on the sea boat plays music with the lyre, it can respond to the sound and swim close to the hull. Once a group of children were playing on the shallow shore, a dolphin heard the sound and frolicked with the children, and when they were happy, they even put the water polos that the children played with and performed the skills of holding the ball. Every day the dolphin came to play with the children, and even a little girl named Baker rode on its back, and it carried Beck on a friendly swim on the sea. There are also baths and trained dolphins that accompany visitors on missions, and they can even dive underwater to retrieve items that have fallen to the bottom of the sea. As for performing some shows, that's certainly not a problem. Some people have witnessed this kind of performance, and many more people have enjoyed many wonderful performances through the screen of the TV.
The dolphin's meat is edible, its skin can be used to make tanning, and its fat can be refined into oil. It is also kept as an ornamental animal in zoos for people to enjoy. Experts are interested in observing and studying its living habits and physiological characteristics. In the former Federal Republic of Germany, a scientist named Kramer observed that dolphins had an unusual ability to follow the sea ship to swim at high speed, and later found that the capillaries in the dermis layer of dolphins dampened the turbulence caused by the hull, and its skin can secrete oily lubricating mucus under the pressure of seawater to reduce friction. Kramer was greatly inspired by this discovery, and then used the principle of bionics to create artificial dolphin skin, which was put on the surface of torpedoes and submarines, greatly increasing the speed of torpedoes and submarines. Later, this bionic technology was used in airplanes, which also increased the flight speed.
Dolphins can be divided into many categories, such as white dolphins, pygmy river dolphins, short-snouted dolphins, etc., distributed in the southeast of the mainland, the southern coast of the coast and Southeast Asia, the Chinese white dolphin (Chinese white dolphin) is a subspecies of white dolphin. The mainland has designated it as a category of key protected animals.