Why do people die, why do fish swim?

It's a natural phenomenon!! Everyone experiences birth, old age, sickness, and death!! It's a natural cycle!!

Fish have the characteristics of being suitable for living in water: the color of the body of the fish is the protective color of the fish. The body is streamlined, large in the middle and small at the end.

The surface of the body is covered with scales, which protect the body; There is a layer of mucus on the surface of the scales, which reduces the resistance of the water when swimming. There is a lateral line on both sides of the body, which is connected to the nerve, which is mainly used to determine the direction and sense the flow of water. The body of a fish has pectoral fins, dorsal fins, pelvic fins, and caudal fins, which are the locomotor organs of the fish in the water.

Fish breathe with gills. There is a swim bladder in the body, the main role is to regulate the specific gravity of the body, the swim bladder in the coordination of the fins, can make the fish stay in different water layers. Fish belong to the lower animals of vertebrates because they cannot live without water all their lives, breathe with gills, heart-atrium-ventricles, a circulatory route, and arterial and venous blood are mixed; In particular, the reproduction of fish is naturally hatched by in vitro fertilization, and the body temperature is not constant.

The role of the fin: The dorsal and anal fins mainly play a stabilizing and balancing role when moving. The tail fin works with the muscles on the side of the body to propel the fish and control the direction.

The main function of pectoral and pelvic fins is to maintain the balance of the fish, cooperate with the body of the fish, and adjust the lifting of the fish. However, pectoral fins are more versatile than pelvic fins, and they can be used like oars to move the fish forward slowly. Because the gills of a fish are only adapted to absorb oxygen from the water and cannot absorb oxygen from the air, it can only live in the water.

It is normal to be born, old, sick and die Fish do not have nails, only scales and gills, so they can swim in the water.

When you die of old age, fish live in the water, just like people live on the shore.

It's not just people who die, but everyone who gets old dies because he won't go.

Sharks have to swim all the time to stay aliveThe shark must constantly swim forward or it will suffocate. There are no fish bubbles.

Sharks can only keep their bodies from sinking to the bottom by swimming constantly in the water.

If you stop, the shark will sink to the bottom, although the shark also breathes with gills, but if you stop in one place for a long time, you can't get enough oxygen, so the shark needs to swim all the time, only then can it get more oxygen from the water for it to consume.

Conservation status

The shark is an ancient fish, and its fossils appear hundreds of millions of years before the dinosaurs, judging from the fragments of shark teeth and spines that have been excavated. In this long history, sharks have disappeared through natural selection, and some species have disappeared, but there are still some vulnerabilities of species in the more than 300 species that are still alive today, such as slow growth and sexual maturity.

Late, the reproduction is also once every two years, and the reproduction rate is also extremely low.

The indiscriminate fishing and killing of sharks by humans is the most important reason for the decline of shark populations. Human hunting is mainly used for both edible and medicinal purposes, and it is a symbol of wealth and status, and it is also extremely expensive.

The reason why a fish's internal organs are still moving after they have been dug out is because the fish's nervous system is still working.

There are two types of death:

1. Cardiac arrest.

2. Brain death.

After the internal organs of the fish are removed, the spine is not severed, and the peripheral nerves of the body are still responsive and not controlled by the brain, and some movement instructions are transmitted and reflexed through the nervous system in the spine, so it can still move in a short time.