Which lake has the most fish?

In fact, the fish in each lake are similar, and there are many, such as Dongting Lake and Poyang Lake.

If you are abroad, you don't know much about it. You only know about it at home.

Fish (scientific name: Piscium) is a general term for aquatic vertebrates with variable temperature. The whole body is covered with bone scales. It breathes through gills, swims through the swing of tail and trunk and the coordinated movements of fins, and feeds on the upper and lower jaws.

It belongs to the vertebrate subfamily of Chordata and is the oldest vertebrate. [1] Fish is rich in animal protein and phosphorus, which plays an important role in the development of human physical strength and intelligence.

Among the five categories of vertebrates, fish is the lowest and appears earliest on the earth. We are familiar with live fish, but we are unfamiliar with the early fish in geological history and how they evolved into live fish. Let's follow the long river of time and go back to the past.

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fish

The earliest known fish fossils were found in the Late Cambrian strata about 500 million years ago, but only scattered scales failed to outline the physical state of fish for us.

It was not until the late Silurian and Devonian 400 million to 350 million years ago that a large number of fish fossils were discovered. Some of these fish fossils are very different from each other in structural characteristics, indicating that there were many kinds of fish at that time. Probably before the fossil record, they had gone their separate ways and had gone a long way on their respective evolutionary paths.

The earliest fish were jawless fish. As the name implies, they have no upper or lower jaws, and only a funnel-shaped mouth is located at the front end of their bodies. This kind of mouth can't take the initiative to eat, and it can only bring tiny creatures into the mouth by electric current. In addition, they have no ventral fins, but a membranous exoskeleton.

Wrapped outside the body. Therefore, jawless fish is also called turtle. Because of the existence of this exoskeleton, some disputes have arisen among scholars: which comes first, cartilage or hard bone? In the process of vertebrate embryogenesis, cartilage always appears first, and then hard bone is formed from cartilage. It is generally believed that individual development reflects systematic development.

Accordingly, in the process of biological evolution, cartilage should be ranked first, and hard bone should be ranked last, but the earliest vertebrates first appeared hard bone. How do you explain this? Some people say that cartilage comes first, but cartilage cannot be preserved as a fossil. Finally, there is no conclusion.

Jaw-less fishes include two distinct classes: Cephalopods and Fin Whales, each of which has its own branch and various representatives of different types, which once flourished. But it didn't last long. By the middle Devonian (about 350 million years ago), most of them were extinct. Because some characteristics of alive lamprey and blind eel are consistent with cephalopods, scholars speculate that the former may be the living representative of the latter. Accordingly, cephalopods should not eventually become extinct.

However, during the more than 300 million years from Devonian to modern times, no intermediate relationship among cephalopods, lampreys and blind eels was found (Figure 14). It is still uncertain how these parasitic modern jawless fish evolved from their armored ancestors.

Pinctada has no living representative and is considered an extinct category. However, because some characteristics of Allosaurus are similar to those of later jaw fish, some people say that Allosaurus may be the distant ancestor of jaw fish. Whether this is the case, more arguments are needed.

The earliest jaw fish is the shield fish, which has not only upper and lower jaws, but also lateral fins. So it is possible to take the initiative to feed. Shield fish are usually divided into Class A and Class B, both of which are covered with armor and most prosperous in the late Devonian. The former can be represented by tail fish, and the latter can be represented by channel scale fish.

Some people think that the shield fish may be related to modern sharks, but others think that it may be closer to bony fish.