The relationship between fish and humans

Fish and humans have species kinship and share the same ancestor. Fish are not only edible for humans, but also delicacies for cats. Goldfish are available for viewing. Flying fish provide bionic models for the development of shipboard missiles. Fish swallow plankton and residues in the ocean, avoiding water pollution and eutrophication. , fish in the sea also provide a food source for whales.

The words "fish" and "surplus" have the same pronunciation. Chinese braised fish at the New Year's Eve banquet means having more than enough every year. Because of the existence of fish, the fishing industry, fishermen, and fishermen were born, and Hemingway's "The Old Man and the Sea" was born.

Extended information:

Fish are generally dioecious, and their gonads are usually paired. Cartilaginous fishes generally undergo internal fertilization and are ovoviviparous, viviparous, or oviparous, while most bony fishes undergo external fertilization. The eggs produced by freshwater fish are either sinking or floating, while saltwater fish are all floating. The sexual maturity of fish has a lot to do with species, nutrition, water temperature, light, etc., and is regulated by gonadotropins.

The fertilized eggs hatch after a certain period of time, and the larvae emit their membranes. The life of a fish is divided into embryonic stage, larval stage, immature stage and adult stage. Among them, the mortality rate of larval fish is the highest.

The distribution of existing fish in the world is extremely wide. They can be found in high mountain waters of nearly 4,000 meters and deep seas of more than 6,000 meters. The ratio of the number of seawater fish to freshwater fish species is 2:1.