A dolphin is a fish or not?

It's always quite difficult to pass by a dolphin show, because where else you will see such graceful and cheerful creatures! Therefore, every year dolphinariums are opened in many cities in the hope of attracting as many viewers as possible. But, despite such overwhelming popularity, there is a halo of mystery around the dolphins even today. And one of the mysteries: who are these amazing creatures? Is it fish or not?

An unimaginable mystery

The dolphin is a playful inhabitant of the seas, which is found in many regions of the globe. Since he lives in the water, unsophisticated people are accustomed to consider him belonging to one of the species of fish. After all, how else to explain the fact that it can not rise to the surface for hours? The presence of fins, which are an indispensable attribute of all the inhabitants of the underwater kingdom, also leads to the same conclusion.

However, scientists, having studied the features of these creatures, came to a completely different conclusion. According to their studies, the dolphin is a representative of the mammalian class. And his closest relatives are whales, killer whales and sea cows. But why?

Compelling evidence

The fact that the 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, that's why a dolphin is not a fish:

1. They do not have gills, but instead these creatures use lungs. They may be slightly different from those of terrestrial mammals, yet they are one and the same organ.
2. All dolphins are warm-blooded. A similar feature is never found in fish.
3. These lovely creatures give birth to live offspring, rather than laying eggs like their underwater relatives do.
4. They feed the children with milk. That is why they are referred to the class of mammals.
5. And finally, after 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 the habitual habitat to the water expanses? What made them move to the new world? What is the true history of the dolphin? And are there facts confirming it?

Reasons for changing habitats

In fact, dolphins are not the only creatures that have changed one element to 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, it is more important than why this happened.

Here, scientists, unfortunately, can not come together in a single opinion. But, most likely, the reason was the shortage of food on land, because of which some species had to adapt to other ways of hunting. In particular, the distant ancestors of all cetaceans, including dolphins, have learned to catch their victims under water. This served as an impetus to the fact that they began to spend more and more time near the reservoirs, until they completely moved into them.

Paleontological chronicle

As for historical evidence, paleontologists have been able to create a relatively accurate record of cetacean mutations. Naturally, it has blind spots, but they are not so significant as to overshadow the whole picture.

The most ancient representative of cetaceans is pakicetus. His remains were found in the territory of modern Pakistan, and according to rough estimates of scientists, they are no less than 48 million years old. Outwardly this animal looked like a dog, but only its thin legs ended with small hooves on their fingers. They lived near water bodies, ate fish or crustaceans, and at the same time they could dip into the water to catch their prey. Pakacetus led a way of life like modern seals. Now let's look at the later ancestors of cetaceans:

• One of the subsequent stages of the evolution of pakitsetus was ambulocetus, which lived about 35 million years ago. This predator was quite impressive size: thus, its length was about 3-3.5 meters, and the weight should have varied within 300 kilograms. Outwardly he resembled a crocodile and could live in water and on land.
• Another direct descendant of pakicetus was rhodocetus. The fossil animal was externally similar to modern seals, but had an oblong mouth with a number of canine teeth. He also had paws, at the end of which, perhaps, had webbeds, allowing him to swim quickly underwater.
• Basilosaurus is another potential relative of whales. True, many scientists believe that he was more a relative of the killer whale, rather than the forefather of friendly dolphins. This is due to the fact that the basilosaurus was huge, allowing it to hunt virtually all the inhabitants of the seas.
• Dorudon is a relative of the basilozaur, 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 who finally got rid of the paws unnecessary for them and got a tail fin.

Mysteries of History

A lot of scientific works have been written about dolphins and many studies have been carried out, but there are still many mysteries related to their evolution today. In particular, scientists still can not determine in which order some species are replaced by others. And yet the fact that these creatures once walked on the earth does not cause any 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 found very interesting information. It turns out that hippopotamus are distant relatives of cetaceans. Just at one stage in the evolution of the dolphins went deep into the seas, and the hippos decided to stay off the coast.

Well, let's discuss other features of these mammals. The more we know about dolphins, the clearer the face becomes that separates this species from other inhabitants of the seas and oceans.

Developed intelligence

Playing dolphins bring interest and a smile to anyone who looks at them. However, only a few know that behind such behavior is hidden remarkable intellect, which distinguishes them against the background of other animals. For example, only some primate species that are closest to humans can compete with them in savagery.

Also, dolphins have a complex system of communication, built on gestures and sounds. Thanks to this, they can coordinate their movement and hunt, as if one coherent mechanism. In addition, these creatures quickly learn, memorizing new images and movements with incredible speed. In particular, that's why they are so popular among circus performers and showmen.

Wonders of echolocation

Dolphins are one of the few animal species that can apply sound waves in their communication. The strength of their signal is so great that their voice can fly a distance of several kilometers. It is rumored that in the past the military used dolphins as underwater mine detectors, since they could find dangerous devices even in the most turbid and deep waters.

Evil temper of dolphins

People believe that these creatures are very friendly, and they have the character of a child. The 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 the dolphin is born a weak calf, 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 dislike.