Casters modern and ancient species, features and development

One of the most interesting puzzles of the oceans and the seas, which was discovered not so long ago, but has ancestors leaving for dinosaurs cysteraea fish. This is the oldest group of fish, which appeared in the interval from 406 to 360 million. years ago. It is with these fish that a large number of guesses, hypotheses that still do not find accurate confirmations are connected with these fish.

Appearance

In appearance, ancient cysteper fish are large inhabitants of fresh reservoirs, the length of which could reach 5 meters, and the mass of several hundred kilograms. The oral apparatus is massive, elongated with several rows of sharp, small teeth. The color of the scales is presumably dark.

The most attention to themselves is attracted by fins, with which the fish moved along the bottom. In structure, they had an internal skeleton, which consisted of individual elements found in the legs and hands of ground vertebrates. The bone skeleton of fins was supplemented by a powerful muscles at their base.

Structure

Features of the structure of the cystera of fish:

  • Lower fins with bone skeleton and developed muscle tissue;
  • Nasal cavities with rear nostrils to facilitate breathing;
  • The vertebrae replaces the chord;
  • The scales are tough, very durable, in its chemical composition it is very similar to human teeth;
  • Both jaws are mobile;
  • The skull with a cystera of fish consists of 2 parts grade and brain.
  • Another important feature in the structure of these ancient fish, thanks to which scientists suggest that it was they who were able to get to land and give rise to the development of amphibians a complex respiratory apparatus. It consisted of two independent parts. One was intended for underwater breathing (gill system), the other for breathing over water (pulmonary system).

    Signs

    Key signs by which ancient cysteper fish differed from others:

  • A large number of small but sharp teeth;
  • Welldeveloped lungs;
  • The unusual shape of the fins, due to which the fish and got their name;
  • The possibility of moving along the bottom on fins.
  • The movement of fins is not synchronous, but alternate, which resembles walking.

    Evolution

    Science highly appreciates the merits of 17 families of cysteraea fish, in evolution, the development of amphibians. Due to the constantly changing living conditions, they were able to adapt, come to the surface, give rise to the development of amphibians.

    Until recently, scientists were sure that this type of fish died out millions of years ago. However, they were able to adapt to all changes on the planet, transform and survive to this day in the transformed appearance.

    Ancient cysteper fish

    Crossoptygii ancient cysterae fish that relate to the outburst. They are one of the oldest representatives of fish on planet Earth. Scientists found fossil remains of cysteraea fish in many parts of the planet, both in fresh reservoirs and large seas, oceans. According to paleontological finds, scientists argue that ancient cysteper fish extracted 70 million. years ago.

    Crossoptygii

    Modern cysteper fish

    Until the beginning of the 20th century, most scientists around the world were sure that cysteper fish completely disappeared. However, in 1938 there was a sensation. In the Halumne River, which is located in South Africa, a living cysterafish fish was caught. Its length was 150 cm, and the mass was 57 kg. A professor who was the first to study this fish (j. Smith), introduced her to the cigarette squad.

    The name of the new fish received “Latimeria”. These fish have a powerful tail, powerful pairing fins. The total number of fins is 7. Of these, 6 are called “paws” due to good development, developed muscle tissue. This is the only representative of the cysteraea fish that can be found in the field of the Comor islands.

    Coelacanth

    Important! Most of the modern scientists agree that the ancestor with a cystera of fish, which continues to live, although gradually dying (for various external reasons) cannot be attributed to a direct ancestor of amphibians. This is due to two reasons. The first Latimers do not have welldeveloped lung tissue, when the ancestors of the first amphibians had developed lungs, so that it was possible to breathe on the surface. The second on the supported scientific theory, amphibians descended from individuals that lived and developed in fresh water. Latimeria live only at the bottom of the ocean, die in small fresh reservoirs.

    Peculiarities

    Latimeria live in oceans and seas. You can find them at a depth of 150 to 250 meters. At night, they hunt alone, often pop up close to the surface to enjoy small fish. During the day, these fish are lost in groups, hid in shelters. They cannot be in the bright light for a long time. On the contrary, the structure and features from the visual apparatus allows them to see them well and navigate under water in the dark

    The floating bubble in Latimeria during evolution turned into a small tube (no more than 8 cm in length).

    Like their distant relatives Latimeria are predators. In their oral cavity, they have a large number of sharp teeth of a small size. Latimeria feed mainly with mollusks and small fish. The main opponent and the main threat to Latimeria are sharks.

    One of the main differences between Latimeria from their ancient ancestor they cannot move along the bottom on the fins.

    Development and reproduction

    Latimeria, like many other fish, have males and females. At the same time, the females are more males.

    For a long time, scientists could not say exactly how modern cysteper fish propagate. The answer to this question would give information about the propagation of longfree individuals. The difficulties with providing an answer to this question were due to the fact that when trying to plant fish even in a large aquarium, she quickly died. This was due to the fact that Latimeria could not adapt to a small depth.

    However, during one of the numerous studies, in the next preparationed carcass of fish, eggs were found inside which there were formed embryos. Eggs have a diameter of 7 to 9 cm, weigh approximately 250-300 grams, have a bright orange hue. In the example described above, 20 such eggs were found inside the carcass.

    Pregnancy in Latimeria lasts 13 months. Young individuals develop extremely slowly. Immediately after birth, the sizes of small Latimeria do not exceed 30 cm in length. Only by 10 years they grow up.

    The last point that needs to be considered why the first cysteper fish died out. There are several versions, however, there is one most common that most scientists support. Ancient cysteper fish lived in swampy ponds, at a small depth. Such water bodies very often dry out, because of which a large amount of fish died. Gradually, new individuals began to adapt to such conditions, they were able to get to the land to find a new reservoir.

    According to scientists, the path of cysteper fish diverges. Some, the most hardy, were able to get to other reservoirs, continued to develop further and survived to this day in the image of Latimeria, changing during evolution. Others were gradually able to adapt to life on Earth and it was from them that the first amphibians appeared.

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