It's always quite difficult to pass by the dolphin show, because where else can you see such graceful and cheerful creatures! Therefore, every year dolphinariums are opened in many cities in the hope of attracting as many spectators as possible. But, despite such overwhelming popularity, an aura of mystery hovers around dolphins even today. And one of the mysteries: who are these amazing creatures? Are they fish or not?
Unimaginable mystery
Dolphin is a playful inhabitant of the seas, which is found in many regions of the globe. Since he lives in the water, inexperienced people are accustomed to considering him as belonging to one of the fish species. After all, how else to explain the fact that it can not float to the surface for hours? The presence of fins, which are an integral attribute of all inhabitants of the underwater kingdom, inclines them to the same conclusion.
However, scientists, having studied the characteristics of these creatures, came to a completely different conclusion. According to their research, the dolphin is a representative of the class of mammals. BUTits closest relatives are whales, killer whales and sea cows. But why is that?
Irrefutable Evidence
The fact that a dolphin is a mammal is evidenced by many factors. They cannot be refuted, so it remains only to accept this point of view. So here's why a dolphin is not a fish:
- They don't have gills, but instead named creatures use lungs. Although they are slightly different from those found in land mammals, they are still the same organ.
- All dolphins are warm-blooded. This feature is never found in fish.
- These cute creatures give birth to live offspring, and do not lay eggs, as their underwater relatives do.
- They feed their children with milk. That is why they are classified as mammals.
- And finally, by examining the skeleton of dolphins, scientists have found a lot of evidence that in the old days these sea creatures walked on land.
But how did it happen that they changed their habitual habitat to water expanses? What made them move to the new world? What is the true history of the dolphin? And are there facts to support it?
Reason for habitat change
In fact, dolphins are not the only creatures that have changed from one element to another. For example, the most famous case is when the first living organisms left the water depths and began to explore the land. True, in this case, everything happened exactly the opposite. However, this is not essential for history. Why is more important to her.it happened.
Here scientists, unfortunately, cannot agree on a common opinion. But, most likely, the reason was the lack of food on land, because of which some species had to adapt to other methods of hunting. In particular, the distant ancestors of all cetaceans, including dolphins, learned to catch their prey underwater. This prompted them to spend more and more time near water bodies until they completely moved into them.
Palaeontological record
In terms of historical evidence, paleontologists have been able to create a relatively accurate record of cetacean mutations. Naturally, there are blind spots in it, but they are not so significant as to overshadow the whole picture.
The most ancient representative of cetaceans is Pakicetus. His remains were found on the territory of modern Pakistan, and according to rough estimates of scientists, they are at least 48 million years old. Outwardly, this animal looked like a dog, only its thin paws ended in small hooves on the fingers. They lived near water bodies, fed on fish or crustaceans, and at the same time could plunge into the water in order to catch their prey. Pakicetus led a lifestyle similar to modern seals. Now let's look at the more recent cetacean ancestors:
- One of the subsequent stages in the evolution of Pacicetus was Ambulocetus, which lived approximately 35 million years ago. This predator was very impressive in size: for example, its length was about 3-3.5 meters, and its weight should have fluctuated within 300kilogram. Outwardly, he looked like a crocodile and could live both in water and on land.
- Another direct descendant of Pacicetus was Rhodocetus. The fossil animal was outwardly similar to modern seals, but had an oblong mouth with a row of fangs. He also had paws, at the end of which, possibly, membranes were located, allowing him to quickly swim under water.
- Basilosaurus is another potential cetacean relative. True, many scientists believe that he was more a relative of the killer whale than the forefather of friendly dolphins. This is due to the fact that the Basilosaurus had a huge size, allowing it to hunt almost all the inhabitants of the seas.
- Dorudon is a relative of the Basilosaurus, who lived with him in the same period. He had much smaller body proportions. It is noteworthy that it was these dolphin ancestors who finally got rid of their unnecessary paws and acquired a tail fin.
Mysteries of history
A lot of scientific papers have been written and a lot of research has been done about dolphins, but today there are still many mysteries related to their evolution. In particular, scientists cannot yet determine in what order some species replaced others. Yet the fact that these creatures once walked the earth is beyond doubt.
By the way, with the development of genetics, many secrets of the universe began to gradually lose ground. So, recently scientists found out very interesting information. It turns out that hippos are distant relatives of cetaceans. Just at one of the stages of evolution, dolphins leftdeep into the seas, and the hippos decided to stay off the coast.
Well, let's discuss other features of these mammals. After all, the more we know about dolphins, the clearer becomes the line that separates this species from other inhabitants of the seas and oceans.
Developed intellect
Playing dolphins arouse the interest and smile of anyone who looks at them. However, only a few know that such behavior hides a remarkable intelligence that sets them apart from other animals. For example, only some species of primates that are closest to humans can compete with them in ingenuity.
Dolphins also have a complex communication system based on gestures and sounds. Thanks to this, they can coordinate their movement and hunt, like one well-coordinated mechanism. In addition, these creatures learn quickly, memorizing new images and movements with incredible speed. In particular, this is why they are so popular among circus performers and showmen.
Miracles of echolocation
Dolphins are one of the few animal species capable of using sound waves in their communication. At the same time, the strength of their signal is so great that their voice can scatter over a distance of several kilometers. It is rumored that in the past the military used dolphins as underwater mine detectors, as they could find dangerous devices even in the most muddy and deep waters.
Angry temper of dolphins
People believe that these creatures are very friendly, and their character is likechildren's. Dolphin - in fact, a very cruel beast. After all, he is a real predator and eats everything that is inferior to him in size.
However, the most cruel in his behavior is the artificial selection of offspring. So, if a weak cub is born to a dolphin, then he can kill him. Not to mention the fact that these creatures have been known to attack other members of their species, fighting for territory, or simply out of personal enmity.
