So this soup is especially suitable for middle-aged people and teenagers. The collocation of fish head and tofu: fish head is rich in glial protein, low in fat and calories, and has the effects of invigorating spleen and benefiting qi, warming stomach, beautifying and moistening skin.
Tofu is rich in protein and calcium, and has the functions of clearing away heat, moistening dryness, promoting fluid production, detoxicating and reducing blood fat. Stewing fish head and tofu into soup can not only warm the body and strengthen the brain, but also make people's skin moist and delicate.
Fish (scientific name: Piscium): It is a general term for aquatic vertebrates with variable temperature. It is covered with bone scales, breathes through gills, swims through the tail and trunk, and feeds on the upper and lower jaws. It belongs to the vertebrate subfamily of Chordata and is the oldest vertebrate. Fish is rich in animal protein and phosphorus, which plays an important role in the development of human physical strength and intelligence.
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 don't have ventral fins, but they have a membranous exoskeleton around their bodies. 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.