Whale - fish or mammal? This question worried scientists long before the advent of modern science. In particular, such a genius of thought as Aristotle tried to solve this problem. And at the same time he came to the same opinion as our contemporaries. But let's talk about everything in order.
The whale is the most magnificent inhabitant of the vast expanses of water. Not a single living creature can be compared with its size and grace, not to mention its amazing ability to sing songs. But what else do we know about these incredible creatures?
Who is a whale?
So what is the meaning of the word whale? According to the dictionary, it is a large mammal that lives in the sea. That is, today, unlike in the old days, it is much easier to find a solution to such a complicated question. But how did it happen that an ancient descendant of whales wanted to exchange land for the ocean?
Well, scientists still do not know the whole truth. However, it is known for certain that 60 million years ago the ancestors of all cetaceans first went to look for food back into the water. Perhaps this was caused by a protracted drought, which destroyed part of the vegetation on the planet or a lot of competition from other animals. But the fact remains - the ancestors of the whales no longer wanted to return back to land.
How did a land animal adapt to life under water?
It should be understood that such a metamorphosis did not occur in one or two years. Evolution is a chain of small changes due to which a living organism constantly mutates for thousands of years. And this ultimately produces a completely new look, radically different from its ancestors.
And yet, after 60 million years, researchers still find in the structure of the skeleton of a whale echoes of those ancient times, when he still walked on his four legs on land. For example, he has a hip bone that is located in his back. And also its front fins have a similar bone structure with most artiodactyls.
After a series of studies, scientists came to an interesting conclusion. It turns out that the closest relatives of cetaceans are hippos. And if you look closely, you can see some similarities in their behavior even today. In particular, their great passion for water.
Cetacean family
It should be noted that the whale is not the only representative of its family. Dolphins and porpoises are also included in the category of marine mammals. How do they differ from other inhabitants of the water depths?
- First, all warm-blooded cetaceans, unlike fish. That is why they so badly need a good fat layer that can protect them from the cold of the underwater kingdom.
- Secondly, this family is not able to extract oxygen from water. Therefore, they must constantly float to the surface in order to replenish their supply of air in the lungs.
- Thirdly, they all feed their children milk. And although this process has slightly changed over the long years of evolution, cetaceans are still mammals.
The whole family is divided into three large subgroups:
- Baleen whales (Mysticeti) - the largest detachment of the family. Its distinctive feature is a special filtering organ “whalebone”, which is located on the upper jaw of the animal. Its main task is to filter plankton from excess impurities.
- Toothed whales (Odontoceti) are, by and large, predators that hunt squid and small fish. This species is able to navigate in water using echolocation.
- Ancient whales (Archaeoceti) - unfortunately, not a single representative of this category has survived to this day.
Whales: general information
Among all the inhabitants of the planet Earth, the whale is the largest mammal. On average, an adult can reach 25 meters in length. For comparison, 4 large buses occupy about the same amount if they are put in one row. It is not surprising that such a colossus weighs about 90-110 tons, and some even more.
These giants live in almost all the oceans of the planet. Which is true, depending on the season, they can migrate from one place to another. This behavior is due to the fact that whales are sensitive to water temperature, and therefore they spend the winter closer to the tropics.
In general, among all representatives of this family, two special subspecies can be distinguished: blue and gray whales. By and large, this division is due to the color of the skin of these animals, but there are other, equally important differences.
Echoes of the past
The gray whale is the oldest member of this family. Scientists have found the remains of these animals, which, according to rough estimates, were about 30 million years old. Previously, these giants lived in almost all corners of the globe, but now they can be found only in the northern part of the Pacific Ocean.
These creatures are used to living in small groups, about 2-3 individuals in each. Although it is often possible to meet a lonely whale, proudly plowing water open spaces. And yet, most giants prefer to live in a group. By and large, this is due to the fact that gray whales have very strong family ties.
Probably, it was this connection that helped them survive dangerous times. Indeed, in the middle of the 20th century, they were almost completely destroyed by whalers hunting for their fat. So, according to scientists, in 1946 the number of these mammals was reduced to 250 individuals. Only thanks to the miracle and the efforts of animal rights activists did tragedy escape. Now the number of these animals has increased to 30 thousand, which gave them new hope for a better future.
Blue whale - the largest creature on earth
As for the blue whales, they are rightfully considered the largest creatures on this planet. Even such a huge animal as an elephant cannot compete with them. These sizes remind us that once similar giants walked all over the earth. Now the blue whale is the only representative of animal giants of antiquity.
This animal does not particularly favor people, and therefore rarely approaches the coast. His favorite environment is the open ocean, where he feels truly free. He moves quite slowly, only at a speed of 10-12 km / h, but in case of danger, it can increase three times.
Like all representatives of its species, the blue whale feeds on plankton. And although this animal has long been replaced by land for water, it still cannot be in it permanently. That is why whales so often float to the surface, while releasing fountains of water from a special hole located on the upper body.
Whale breeding
Whales are marine animals whose numbers have often declined to catastrophic levels. The reason is people hunting for their meat and fat. They are the main culprits of these tragedies, but not the only ones.
Another factor affecting a population of any species is its ability to reproduce. So, the problem is that these creatures bring posterity into the world no more than once every one or two years. And at the same time, the female gives birth to only one kitten, less often - two. In this case, depending on the subspecies of whales, pregnancy can last from 9 to 18 months.
It is pleasant that the mother always treats her cub very carefully. Those, in turn, grow very quickly and gain weight. So, on average, a kitten can gain about 50 kg of live weight per day. Therefore, do not be surprised that for some seven months it can reach up to 14 meters in length and weigh 20-25 tons at the same time.
And although puberty in whales occurs at the age of 4-5 years, they become full-fledged adults only at the 14-15th year of their life.
