Whales are mammals and the largest animals in the ocean. Whales are very large, with a maximum overall length of more than 30 meters and a minimum body length of 10 meter. At present, the largest known whale weighs about 190 tons, and the smallest whale weighs 2000 kilograms. A sperm whale weighing more than 40 tons was found in China, about17m long. Whales are shaped like fish and spindle; The head is big, the eyes are small, and the auricle is completely degraded; The neck is not obvious; The forelimbs are fin-shaped and the hind limbs are completely degenerated; Most species have fins on their backs; The tail is a horizontal fin, which is the main motor organ; Toothed or toothless; One or two nostrils, growing on the top of the head; Hair on the mouth (a few hairless); There is a thick layer of fat under the skin, which can keep warm and reduce the proportion of the body. Breathe with your lungs, inhale at the surface and dive into the water. Can dive 10 ~ 45 minutes. They usually feed on plankton, mollusks and fish. It is viviparous. Usually, each fetus gives birth to a child and feeds the calf with milk. But many people classify them as fish. In fact, they are not fish, but mammals. They are distributed in the oceans of the world. Whales must surface to breathe at regular intervals. Its nostrils are overhead. When it comes to the surface, it will spit out a column of water. Different whales have different water columns. The water column ejected by baleen whales is vertical, high and thin, while the water column ejected by toothed whales is inclined, thick and short. Experienced people can calculate the species, size and age of whales by observing the water column.

Edit the habits of this whale.

The reproductive ability of whales is very slow, and only one calf can be born every two years on average. Due to the killing of human beings and the pollution of the marine environment, the number of whales has decreased sharply. For example, nearly 360,000 blue whales, the largest cetacean, were killed in the 20th century, and now there are less than 50 left.

Whales are distributed in all the oceans in the world. It is an aquatic mammal that breathes with its lungs. Its species are divided into two categories: baleen whales, toothless whales, baleen whales, two-nostril whales, baleen whales, blue whales, humpback whales, gray whales and so on. , relatively mild, generally eat microorganisms and small fish and shrimp; Toothed whales have sharp teeth and no baleen, and usually have one or two nostrils. There are sperm whales, narwhals, killer whales and other species, with fierce temperament and generally carnivorous. Most of the oxygen in the ocean and 60% of the oxygen in the atmosphere are made by phytoplankton. The baleen whale is the enemy of phytoplankton. In addition, toothed whales also help to maintain the ecological balance of fish. Toothed whales are large mammals that feed on fish.

Body structure

Cetaceans are characterized by constant body temperature, about 35.5℃. Bare skin, no body hair, only a few bristles on the nose and mouth, no sweat glands and sebaceous glands. The fat under the skin is very thick, which can keep the body temperature and reduce the proportion of the body in water. The skull is developed, but the skull is smaller, the face is larger, the frontal bone and maxilla are obviously prolonged, forming a long snout. The neck is not obvious, the cervical vertebra is healed, and the head is directly connected with the trunk. The forelimbs are fin-shaped, the toes are not separated, there are no claws, and the elbow and wrist joints cannot move flexibly, which is suitable for swimming in the water. The hind limbs are degenerated, but there are still pelvic and femoral residues, and residual bone fragments can be seen. The tail degenerates into fins, and the skin at the end expands horizontally from left to right, forming a pair of large tail leaves without bone support. The spine gradually tapers in the long and narrow caudal trunk and finally disappears before entering the caudal fin. Unlike fish, the caudal fin can swing up and down and is the main organ for swimming. Some species also have dorsal fins to balance their bodies. Their bones have spongy tissue, and there is more fat in the body cavity, which can increase the volume of the body, reduce the proportion of the body and increase buoyancy.

killer whale

Their eyes are small, without lacrimal glands and transient membranes, and their eyesight is poor. There is no outer ear shell, and the external auditory canal is very thin, but the hearing is very sensitive. It can feel ultrasonic waves, find food by echolocation, contact companions or avoid enemies. There are 1-2 external nostrils, located on the top of the head, commonly known as spray holes. Generally, the closer the nostril is, the higher the degree of evolution. Breathing with lungs, there is a lung on the left and right, and there are many capillaries in it, which are elastic and can help the circulation of oxygen and adapt to the gas exchange on the water. You need to surface for air every once in a while, and you can also dive for a long time. There are 10 20 pairs of ribs. The stomach is divided into four chambers. Most kidneys are tumor-like. Male testicles are located in the abdominal cavity. Female animals give birth and breastfeed in water. The uterus has two horns and a pair of breasts, which are located at the cleavage on both sides of the reproductive fissure, and the nipples are slender. Milk is rich in calcium, phosphorus and a lot of fat. Young whales have teeth in the embryonic period, but whales' teeth are replaced by beards at birth, and toothed whales' teeth are preserved for life.

A whale is a mammal that lives in water. It has the same physiological characteristics as terrestrial mammals, such as breathing with lungs and viviparous, and is equipped with some special physiological structures evolved to adapt to the aquatic environment.

suborder

Under Cetacea, it is divided into two suborders, namely Mystical Cetacea (Blaleen whale) and Toothed Cetacea (Toothed whale). The grouping of these two groups is mainly determined by their different feeding patterns. The main morphological feature of the suborder baleen whales is that they have no teeth, but they have huge baleen whales, which can be used to screen plankton, so they are filter feeders. The main feature of Toothed Whale suborder is that it has teeth and is a carnivore. The number and arrangement of its teeth will be affected by eating habits. There are about 79 species of 13 families in the world.

strange hobby

Whales are not fish, but mammals. It has many characteristics very different from fish. For example, the average fish swings its tail fin from side to side to make its body move forward, while the whale swings its tail fin up and down. They use the flippers at the front end to keep balance and control the direction of force. Some whales have fins at the upper end of their backs to keep their bodies upright.

Whales are social animals. They usually live in groups in the sea, but when whales breathe, they need to swim to the surface. At this time, whales breathe through the nostrils on their heads, and when they exhale, the water in the air will condense, forming the familiar fountain shape. Experts can even tell the species of whales from the height, width and angle of water spray. There are many kinds of whales, which can be roughly divided into toothed whales and baleen whales.

There is a very thick layer of fat under the skin of whales, called whale oil. It can keep whales warm and store energy for a rainy day. Because there are many special structures in the whale, it can hold its breath for a long time and slow down its heartbeat, so when it sinks to the bottom of the sea, it will take a long time to surface again. In addition to the oxygen storage structure, when a certain part of the body needs a lot of blood supply, the body will also have a special function of centralized supply.

Whales usually find a safer place to sleep. I like a few heads in a circle and floating on the sea. If you hear anything, swim away.

condition

At present, at least five species of whales in the world 13 are on the verge of extinction because of human hunting. In order to protect whales, the International Whaling Commission banned commercial whaling from 1986, but this ban was relaxed in 1987, allowing limited whaling for research purposes. Despite strong opposition, some countries (especially Japan) still kill a large number of whales every year in the name of "scientific research".

The creation of the Chinese character "whale" clearly shows that the ancients thought the whale was a big fish, not to mention the word "whale". We can't blame the word-makers for their lack of biological knowledge, because cetaceans, including whales, dolphins and porpoises (smaller dolphins), are really similar to fish: their long bodies are streamlined, their tails are leaflike, their hind limbs degenerate to nothing, and only a little residue can be found inside their bodies, all of which are suitable for living in water.

hunchback

Scientists believe that mammals and dinosaurs entered the evolutionary stage at about the same time, and they did not live well in the era when giant reptiles were rampant. Dark clouds didn't have a chance until an extinction event-it is generally believed that an asteroid hit the earth 65 million years ago-destroyed the dinosaur family. During the Tertiary period between 50 million and 65 million years ago, all mammals lived on land, and the ancestors of modern whales were no exception. For some reason, some animals running on all fours began to return to rivers and oceans in Eocene 50 million years ago. In less than 8 million years, their body shapes and living habits have undergone tremendous changes.

These discoveries, especially the bucky cetaceans, have excited scientists enough, because they are a transitional type between land mammals and modern cetaceans, and once again provide beautiful evidence for evolution. However, these transitional fossils are more inclined to the whale side, either amphibious or completely adapted to marine life. There are two important questions unanswered: What is the land ancestor of cetaceans-the most primitive cetaceans that can only run but not swim? Among the existing mammals in the world, which one has the closest relationship with cetaceans?

Scientists are committed to studying the evolution of whales in more detail, and different professionals have different methods. According to the characteristics of fossil teeth and ears, paleontologists tend to think that whales are closely related to the middle class animals, which are extinct ungulates that lived in the tertiary period. Molecular biologists who study the DNA characteristics of existing animals prefer hippopotamus, believing that this modern cloven-hoofed animal is a close relative of whales.

On September 20th this year, Tavison published a report in the British magazine Nature, saying that his team had newly discovered two kinds of ancient whale fossils from Pakistan, which were completely terrestrial. The next day, gingerich reported in the American magazine Science that two other ancient whale fossils, which were also dug up in Pakistan, had developed limbs and might be amphibious. Their new findings show that cloven-hoofed animals such as cattle, hippos, pigs, camels and giraffes are closely related to whales. For gingerich, it may take a little more effort to put forward this view, because he originally claimed that the suborder HYMENOPTERA is a close relative of whales.

As far as the whole marine mammals are concerned, whales have the most species and the largest number. Whales can be divided into two categories: one is called baleen whales, which have no teeth in their mouths and only beards; The other is called toothed whale, which keeps its teeth in its mouth when not in use. Although there are not many kinds of baleen whales, they are huge and become the main hunting targets of human beings. There are blue whales with huge bodies, right whales with slow movements and generally large heads, humpback whales with short arms and funny movements, minke whales with small mouthparts and so on. There are many kinds of toothed whales, except sperm whales, the others are generally small, such as killer whales and dolphins. Although the whale's body varies in length and thickness, it is always streamlined and looks like a fish, so people call it a whale. However, whales are animals. It also like people, constantly surfaced to breathe air. Sometimes on the sea, we can see the white fog columns ejected by whales when they exhale, some of which are as high as ten meters, like fountains, which are very spectacular.

train

Whales are mammals that live in water all their lives. They are so dependent on water that they can't live without it. In order to adapt to life in water and reduce resistance, their hind limbs disappear and their forelimbs become paddles. The body becomes streamlined, like a fish. So their diving ability is very strong. Dolphins (small toothed whales) can dive to a depth of 1 00-300m and stay for 4-5 minutes, fin whales can stay underwater at a depth of 300-500m1hour, and sperm whales (the largest toothed whales) can dive below1000m and stay in the water for 2 hours. 1955, a sperm whale was found dead in the sea near Ecuador, and its diving depth reached1133m. A sperm whale was found entangled in a cable and died at a depth of 2200 meters near Lisbon, Portugal, which is the deepest record of mammal diving so far. 1969, a sperm whale was able to swim to the surface after diving 1: 52. After people killed it, they found a small shark in its stomach that had just been swallowed an hour ago. According to analysis, this shark only lives in the depth of 3 192 meters. It can be seen that sperm whales can dive to a depth of 3000 meters in the ocean.

Edit the classification of this whale.

Divide whales into two groups:

Toothed whale: Marine behemoths with teeth, such as sperm whales and killer whales (also known as killer whales), whose teeth are not as sharp as those of sharks, nor are they updated as frequently as sharks. But tough and strong.

Baleen whale: A whale with baleen whales. In fact, these long beards are horned teeth that grow in the mouth and are used to filter water and catch shrimps and other small animals eaten by whales. These teeth replace teeth.

Whales are viviparous mammals, not fish. It takes a year for calves to grow up on breast milk. Fish are oviparous vertebrates. Whales generally have no habit of taking care of their young. Whale's "fins" actually evolved from limbs. Fish is not. Whales breathe with their lungs; Fish breathe through gills. Whales are warm-blooded animals; Fish are warm-blooded animals. You can't tell a whale from a fish by whether it has scales or not. Because many fish have no scales.

According to the species, baleen whales have two different hunting methods.

Defatted type: fin whales, for example, filter plankton in the process of slow swimming, with their mouths half open, and filter water out from the middle of their whiskers.

Swallowing type 1: When this whale approaches a big beach of shrimp, it opens its mouth to swallow a lot of water and puts it into a can.

whale

There is a slender, folded abdomen. As soon as the mouth is closed, the whale tongue rolls up the water filtered by the whale's teeth. For example, a blue whale can swallow 25,000 liters of water at a time.

Swallowing type 2: The baleen whale opens its mouth to swallow the fish and shrimp together with the water, then filters out the water through the filter plate, and then swallows the fish and shrimp into its stomach.

Every year, some whales leave the food-rich polar ocean to find warmer waters to give birth to their offspring. They traveled thousands of kilometers in a certain period of time a few months later. Every winter, many tourists go to Wan Li by boat to meet them in the Hawaiian Sea and the Gulf of Mexico. For sperm whales, males cannot migrate because there are not enough squid in the breeding area.

Edit the number of whales in this paragraph.

On July 25th, the authoritative American science magazine Science announced that according to the latest scientific research, the number of whales in the North Atlantic is about 2-24 times that of now. This study was confirmed by analyzing the genetics of whales currently living in the North Atlantic. Because mitochondria in genetic genes can be inherited, a professor at Harvard University began to study from here how many kinds of whales are needed to cause the current whale DNA diversity, and finally came to the conclusion that before humans began commercial whaling, the number of whales in the North Atlantic was about 865,000. Among them, there are more than 4,000 blue whales, but today, there are less than 50!

Although the authenticity and reliability of this research method need to be further verified, it is an indisputable fact that the number of whales before human beings started commercial whaling was much larger than now. Anti-whaling activities in European and American countries will also be further intensified.

Japanese commercial whaling is a commercial whaling activity carried out by Japanese fishermen under the pretext of "scientific investigation" with the encouragement of the Japanese government. It is the only commercial whaling activity in the world (most countries in the world have banned commercial whaling since 1986), and even the commercial killing of some rare whale species has been widely protested by Greenpeace.

According to the whale survey report of the University of Auckland in New Zealand, although the number of humpback whales has recovered slightly, it is still not enough to support commercial whaling. Professor Baker, a whale expert, thinks that humpback whales near Fiji Islands have disappeared, for example, there are only about 400 humpback whales near New Caledonia, and the number of minke whales has decreased to 1/3.

Edit the whale species in this paragraph.

Species of whales: As far as the whole marine mammals are concerned, whales have the most species and the largest number. Whales can be divided into two categories: one is called baleen whales, which have no teeth in their mouths and only beards; The other is called toothed whale, which keeps its teeth in its mouth when it is not needed. Although there are not many kinds of baleen whales, they are huge and become the most important hunting targets for human beings. There are blue whales with huge bodies, right whales with slow movements and generally large heads, humpback whales with short arms and funny movements, minke whales with small noses and so on. There are many kinds of toothed whales. Except for sperm whales, others are generally small, such as killer whales. Although the whale's body varies in length and thickness, it is always streamlined and looks like a fish, so people call it a whale. However, whales are animals. It also like people, constantly surfaced to breathe air. Sometimes on the sea, we can see the white fog columns ejected by whales when they exhale, some of which are as high as ten meters, like fountains, which are very spectacular. Due to the pursuit of human beings and the destruction of the environment, the number of blue whales is currently less than 50.