It is always quite difficult to get past dolphin shows, because where else will you see such graceful and funny creatures! Therefore, dolphinariums are opened annually in many cities in the hope of attracting as many spectators as possible. But, despite such a staggering popularity, even today there is a halo of mystery around dolphins. And one of the mysteries: who are these amazing creatures? Is it fish or not?
Unimaginable riddle
Dolphin is a playful inhabitant of the seas that is found in many regions of the globe. Since he lives in water, inexperienced people are accustomed to consider him to belong to one of the species of fish. 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 the inhabitants of the underwater kingdom, leads 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. And his closest relatives are whales, killer whales and sea cows. But why so?
Hard evidence
The fact that a dolphin is a mammal is evidenced by many factors. It is impossible to refute them, so it remains only to accept this point of view. So this is why a dolphin is not a fish:
- They have no gills, but instead these creatures use the lungs. Although they are slightly different from those of terrestrial mammals, it is still one and the same organ.
- All dolphins are warm-blooded. A similar feature is never found in fish.
- These cute creatures give birth to living offspring, and do not lay eggs, as their underwater relatives do.
- They feed children milk. That is why they are classified as mammals.
- And finally, by examining the skeleton of dolphins, scientists 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 habitat to water open spaces? What made them move to a new world? What is the true dolphin story? And are there facts supporting her?
Reasons for a change in habitat
In fact, dolphins are not the only creatures that replaced one element with another. For example, the most famous case is when the first living organisms left the water depths and began to develop land. True, in this case, everything happened exactly the opposite. However, for history this is not essential. For her, why this happened is far more important.
Here scientists, unfortunately, cannot agree on a common opinion. But, most likely, the reason was a shortage of food on land, due to which some species had to adapt to other hunting methods. In particular, the distant ancestors of all cetaceans, including dolphins, learned to catch their victims underwater. This was the impetus for the fact that they began to spend more and more time near ponds, until they completely moved into them.
Fossil record
As for historical evidence, paleontologists were 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 as a whole.
The most ancient representative of cetaceans is pacicetus. His remains were found in 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 legs ended in small hooves on the fingers. They lived near ponds, ate fish or crustaceans, and at the same time they could plunge into the water in order to catch their prey. Pacicetus led a lifestyle like modern seals. Now let's look at the later ancestors of cetaceans:
- One of the subsequent stages of the evolution of pacicetus was ambulocetus, who lived about 35 million years ago. This predator was very impressive in size: for example, its length was about 3-3.5 meters, and its weight was supposed to fluctuate within 300 kilograms. Outwardly, he was like a crocodile and could live both in water and on land.
- Another direct descendant of pacicetus was rhodocetus. The fossil animal was similar in appearance to modern seals, but had an oblong mouth with a number of fangs. He also had paws, at the end of which, perhaps, membranes were located, allowing him to quickly swim underwater.
- Basilosaurus is another potential cetacean relative. True, many scientists believe that he was more likely a relative of the killer whale than the forefather of friendly dolphins. This is due to the fact that the basilosaurus was huge in 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. Possessed much smaller proportions of the body. It is noteworthy that it was these ancestors of dolphins that finally got rid of their unnecessary paws and acquired a tail fin.
Riddles of history
A lot of scientific works have been written about dolphins and a lot of research has been done, but today there are still many mysteries associated with their evolution. In particular, scientists still cannot determine in what order some species replaced others. And 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 give up their positions. So, recently, scientists have discovered very interesting information. It turns out that hippos are distant relatives of cetaceans. Just at one of the stages of evolution, dolphins went deep into the seas, and 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 more obvious is the line that separates this species from other inhabitants of the seas and oceans.
Developed intelligence
Playing dolphins arouse interest and a smile from anyone who looks at them. However, only a few know that such a remarkable intelligence is hidden behind such behavior, distinguishing them from the background of other animals. For example, only some species of primates that are closest to humans can compete with them savvy.
Dolphins also have a complex communication system built on gestures and sounds. Thanks to this, they can coordinate their movement and hunt, like one coordinated mechanism. In addition, these creatures quickly learn, memorizing new images and movements with incredible speed. In particular, that is why they are so popular among circus performers and showmen.
The wonders of echolocation
Dolphins are one of the few species of animals that can apply sound waves in their communication. Moreover, the strength of their signal is so great that their voice can fly a distance of several kilometers. Rumor has it that in the past, the military used dolphins as underwater mine detectors, as they could find dangerous devices even in the muddy and deepest waters.
Dolphin angry temper
People believe that these creatures are very friendly, and their character is like a child. Dolphin is actually 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 in a dolphin, then he can kill him. Not to mention the fact that there are cases when these creatures attacked other representatives of their species, fighting for territory, or simply because of personal hostility.