Lamprey is a typical migratory fish that lives in the sea for a period of time. Enter the river from the sea in autumn and spend the winter in the lower reaches of the river. In May and June of the following year, when the water temperature reaches about 65438 05℃, it will return to the upstream for breeding. Lamprey chooses shallow water, fast-flowing water and gravel-bottomed waters to dig holes and nest and lay eggs. The male fish sucks the female fish's head with a sucker and ovulates and inseminates at the same time. Eggs are extremely small, with 8,000-65,438+10,000 eggs each time, and the eggs stick to the gravel in the nest. All the parent fish died after spawning. Eggs become young eels soon after hatching. Young eels live in mud and sand, bury under mud and sand during the day and come out for food at night. The larval fish at this stage is very different from the adult fish, and the mouth sucker is underdeveloped and triangular, which is called Shayin juvenile fish and lives a free life. The life span of lamprey is about 7 years. After living in the river for 4 years, the young fish metamorphosed into the sea in the fifth year, lived in the sea for 2 years, and then migrated back to the river to lay eggs.

Fortunately for its host, less than half of lamprey's life is in dangerous adulthood, which is about three years in the seven years of "fish life". Most of the rest of the time, it spends its leisurely larval stage at the bottom of the river, burying its body in small rubble and only showing its head. In this way, although they can't see, there are also plankton or algae microorganisms falling into their U-shaped mouths. But magically, they are actually a small investigation team of adult eels. Once a good spawning site is found, it will secrete pheromones and spread in the water, and those adult lampreys who want to spawn will smell it and find it. This process looks like these larvae say to their future parents, "This is a good place to lay eggs. Look, this is where we thrive. " This method is good and can effectively improve the survival rate of reproduction.