Question 1: Why do fish always choose to go upstream? The movement of fish in water can generally be divided into two types: one is irregular, such as temporarily avoiding enemy attacks, chasing prey, or other accidental movements. Sometimes this movement happens continuously, and sometimes it doesn't appear for a long time. The distance or duration of movement is generally short, and there is no certain direction and periodicity, so it is called "unidirectional movement". The other is the opposite. Its movement has a purpose, a long time and distance, a certain route and direction. Under certain environmental conditions, it repeats periodically at some time in a year or several years, thus forming the so-called "directional movement", which is also commonly known as migration. Fish migration is a very interesting phenomenon in nature. Salmon and eels are typical examples. Salmon that spend their adolescence in the ocean swim to the estuary in groups when they are sexually mature, and swim upstream at a speed of 40 to 50 kilometers day and night, laying eggs in the upper reaches of rivers hundreds of kilometers away from the ocean. During the migration, they don't want to eat or drink, just look forward, and they don't flinch when they encounter shallow canyons and rapids. Sometimes in order to jump over obstacles, I hit a stone wall and died. After arriving at the destination, I was exhausted from body fat and gaunt because of the long journey. Most salmon die after spawning and cannot take care of their offspring. After the fertilized egg develops into a small fish in the river, it goes down the river, returns to the sea after four or five years, and then returns to the upper reaches of the river to lay eggs along the route passed by parents.

Eels living in rivers are the opposite of salmon. They will lay eggs in the sea when they grow up. Eels also have the spirit of going forward in the breeding season. When they are blocked by the river and can't move forward, they will leave the water regardless of their lives, climb over many obstacles along the wet grassland and rush to the sea. After completing the mission of breeding offspring, some eels are exhausted, and some return home with their children.

In many cases, migratory fish are in groups. For example, fish in the Black Sea is a famous example. Flocks of seagulls are often unable to fly because of the crowded fish on the sea surface, and sometimes a large number of fish swim in, which actually silts up the bay. One hundred years ago, the port of Balaclava was crowded with a large number of fish, and a large number of fish suffocated and rotted, which caused a disaster and became an anecdote in the world.

What causes fish to migrate like this? We say that this song is first influenced by external conditions. Like other animals, fish are affected by temperature. Because fish live in water, except temperature, current and salinity, it has an impact on fish migration. Ocean current plays an important role in the migration of fish, especially the migration of juvenile fish. Because for young fish, they lack the necessary sports ability and can't fight against the strong current, so they can only be completely "held" by the current and drift with the flow. The migration of many adult fish is also greatly affected by ocean currents. Because there are many sensory organs called "lateral lines" on both sides of their bodies, they are particularly sensitive to water flow, which can help fish determine the speed and identify the direction of water flow. Different kinds of fish have different reactions to the action of current. Some go upstream and some go downstream. It can be said that the long-distance migration of fish is mostly due to the action of ocean currents. Water temperature also plays an inestimable role in fish migration. Most fish are as sensitive to temperature as migratory birds. They can only survive at a certain water temperature. When the water temperature changes, fish will look for an environment suitable for survival, which will lead to migration. For example, Pseudosciaena crocea and Pseudosciaena crocea along the coast of China leave the coast in late autumn and early winter and swim to the deep sea to spend the cold winter. This migration is called "wintering migration". Fish migration is also related to the salinity of water. The change of salt in water will cause the physiological changes of fish, such as reducing or increasing the salt in fish blood, which can make the nervous system of fish in an excited state. Different kinds of fish or the same kind of fish have different adaptability to salinity in water at different stages of life. For some fish, the boundary of different salinity waters seems to be an insurmountable gap, but for another fish, it is also a "signpost" on their migration path.

It is reported that the migration of fish is also related to the activity of sunspots. The intensity of sunspot activity affects the amount of heat and particles emitted by the sun. This change will cause the change of atmospheric circulation, which will affect the water temperature. With the change of ocean current, the migration of fish also changes. It is observed that when sunspot activity is strong, atmospheric temperature and seawater ... & gt

Question 2: Why do fish like going upstream? The respiratory organ of fish is gill, which is covered with capillaries and absorbs oxygen dissolved in water. When fish swim upstream, the water flow is faster, which can increase the gap between gill filaments and absorb oxygen better. Coupled with the fast water flow, it can also replenish the fish's demand for oxygen in time, so fish like to go upstream!

Question 3: Why do fish like going upstream? Fish have the characteristics of top-flow swimming, which is convenient for fish to orient and feed. Top-flow swimming has a critical water velocity. When the flow velocity is less than the critical flow velocity, the fish does not respond to the current. When the current reaches a certain level, the fish's activity will be enhanced and they will swim against the current actively. When the speed exceeds the limit swimming speed, the fish will remain in the top flow state and be washed away by the current.

Question 4: Why do fish always go upstream? Fish go upstream, which means they have to go far away to lay eggs, such as salmon. This is a process of life, just like having a baby. For the sake of future generations, they have to go upstream.

Question 5: Why do fish always go upstream? Live fish swim against the current, while dead fish drift with the current. Well, I found the answer online. But strictly speaking, there are fish that go upstream, such as salmon, which is a kind of salmon. Many fish spawn upstream every year.

Question 6: Why do goldfish swim against the current? If you put an iron ball in the water tank, the water will rotate when it is still. It seems that it is facing a downstream countercurrent with respect to water. I don't know if the relativity of motion gives you the illusion. Of course, it may also be because goldfish are timid and dare not move, and they will collide left and right along the current too quickly to control.

Satisfied, please adopt.

Question 7: What's the name of the fish swimming against the current? What the landlord is talking about is not a fish that flows against the current, but a fish that migrates. Migratory fish swim back to their birthplace to lay eggs and reproduce the next generation in order to breed. For example, salmon is a migratory fish.

Question 8: My system is windows me. When installing the download software of Baidu Xiaba, there is always a 5-point error.