Dolphin delphinidae; dolphin
Dolphin belongs to mammals, cetaceans, odontaceans and dolphins. It is a small cetacean, with nearly 62 species, distributed in all oceans of the world. It is 1.2 ~ 4.2 meters long and weighs 23 ~ 225 kilograms. Dolphins generally have sharp mouths, with about 10 1 fangs in the upper and lower jaws. They mainly feed on small fish, squid, shrimp and crab. Dolphins like to live a "collective" life, and the number ranges from a few to hundreds. Dolphin is a marine mammal with superb skills and intelligence. After training, you can play table tennis, jump in the ring of fire and so on. Dolphin's brain is the most developed among animals except humans. Human brain accounts for 2. 1% of my body weight, and dolphin brain accounts for 1.7% of my body weight. The dolphin's brain consists of two completely separate parts. When one part is working, the other part is fully rested. Therefore, dolphins can stay awake all their lives. Dolphins judge the distance, direction, position, shape and even the nature of objects by echolocation. Some people do experiments, blindfold dolphins and muddy the water, so that they can catch up with the food thrown at them quickly and accurately. Dolphins not only have amazing hearing, but also superb swimming and unusual diving skills. Some tests show that the diving record of dolphins is 300 meters deep, while people can only dive 20 meters without diving suits. As for its swimming speed, it is unmatched by human beings. The speed of dolphins can reach 40 kilometers per hour, which is equivalent to the medium speed of torpedo speedboats.
Evolution of dolphins
Dolphins, as well as whales and porpoises, evolved from terrestrial mammals and are considered similar to cloven-hoofed animals. In the present dolphin skeleton, two rod-shaped bones located in the pelvis are considered as degenerated hind limbs. About 50 million years ago, they returned to live in the sea. See cetacean evolution for details.
In the kingdom of cetaceans, there are the most species of Dolphinidae, and there are more than 30 known species in the world. Although some species are called whales, such as killer whales and fake killer whales, they are actually members of the dolphin family.
Dolphins generally refer to members of the family Dolphinidae, while baiji is a puffer fish, not a dolphin strictly speaking.
Kingfisher is the most diverse and familiar family among cetaceans, and its members have certain differences in size and habits, which can be divided into several different subfamilies, and some people divide them into different families. Most members of the Dolphinidae are small, including the smallest cetaceans, which feed on fish or mollusks, and some members are large and can prey on other marine animals. Dolphinidae can be divided into long beak, short beak and beakless in appearance. Most of them have dorsal fins on their backs, and a few have no dorsal fins. Dolphinidae members are most abundant in tropical coastal areas, but they can also be seen in other sea areas, and some of them can go deep into rivers. The most famous member of the Dolphinidae is the truncated dolphin, a dolphin that often performs in aquariums. Bottlenose dolphins are widely distributed in coastal areas and oceans, and different members are also different. Some people divide them into several different species, and some bottlenose dolphins are the largest beaked dolphins. Another famous member of the Dolphinidae is Orcinus orca, also known as killer whales and killer whales. It is the largest species of the Dolphinidae and the fiercest of all marine animals. Black whales, like bottlenose dolphins, are widely distributed and used for domestication and performance. Different groups of killer whales have different eating habits. In addition to the famous groups that feed on other marine animals, some feed on fish and squid. Sotalia fluviatilis, an Amazon white dolphin, is a representative of the dolphin family who entered the fresh water life. Amazon White Dolphin is the smallest long-beaked dolphin, which looks like a smaller Amazon puffer fish, but prefers open water, unlike the Amazon dolphin, which will enter the submerged forest.
Living habits of dolphins, dolphins are marine animals that breathe on the surface of the water, and each breath can last for 20 to 30 minutes underwater. Dolphins were breathing when people saw them jump out of the water at sea. At the same time, dolphins mostly live in shallow waters and rarely swim into the deep sea. They will carry out different activities in different places. When resting or playing, they will gather in the bay near the beach, and when preying, they will appear in shallow water and rocky places.
Dolphins jumped out of the water. Dolphin is a clever and very clever animal. They don't run away from people like timid animals in the forest, and they don't show their teeth when they meet people like wild animals in the mountains. Dolphins are always very docile and amiable, and sometimes even more friendly to humans than dogs and Malays.
We have heard many stories about dolphins saving people from drowning, and reports about dolphins playing with people are often heard, and some stories even become sensational news. After learning and training, dolphins can even imitate the voices of some people. In 1970s, three American scientists taught two dolphins 25 words. Recently, four scientists, including Dr. Owens of the Pacific Foundation, trained two dolphins and spent three years teaching them 700 English words. However, some scientists believe that the "language" or "dialect" of animals should not be described too strangely.
But dolphins do have unusual intelligence. Its brain size and quality are also among the best in the animal kingdom. At present, scientists have two different views on the intelligence of animals: one thinks that chimpanzees are the most evolved and capable of all animals; The other thinks that the intelligence and learning ability of dolphins are similar to those of apes, or even higher. Therefore, some people call dolphins "wisdom in the sea".
In order to prove that dolphins can learn, as early as 1959, a man named Lili did an experiment on a dolphin. He inserted electrodes into the pleasure center and pain center of dolphins. When current stimulates the pleasure center or pain center of dolphins through electrodes, it will produce pleasure or pain. Then the dolphins are trained to touch the metal pieces on their heads and control the on-off of the current. If the electrode is inserted into the pain center of the dolphin, as long as it is trained for 20 times, the dolphin will choose to cut off the power supply to make the pain disappear. If you are a monkey, you need hundreds of trainings to learn to control the switch. This shows that dolphins have stronger learning ability in some aspects.
Dolphins are friends of human beings, and they are very willing to get close to human beings. Dolphins at Mon Kemi Beach in Australia have established friendship with human beings, which has brought great joy and surprise to people. Maybe there will be more dolphins in the future, and they will establish contact with humans in more places. This wish is not an illusion: with the deepening of people's research on dolphins, we will uncover more secrets about dolphins, and then our communication with dolphins will be easier, more intimate and more friendly!
Speaking of dolphins, people have heard that they have extraordinary wisdom and ability. In the aquarium, dolphins can perform various wonderful jumping movements according to the instructions of the trainer. They seem to understand the information transmitted by human beings and take action. People can't help but wonder how smart this beautiful marine animal is. So, how high is the wisdom and ability of dolphins? Is it possible for them to increase communication with humans? Judging from the structure and ecological characteristics of dolphin brain, it is time for human beings to seriously consider the evolutionary relationship of intelligent life on earth.