Can fish sleep? How can I know if the fish is sleeping?

Of course, fish need to sleep. They will not only take time to rest, but also take a nap like us, and find opportunities to catch up on sleep when they don't get enough sleep. So the focus of the problem becomes, how can we judge that the fish is asleep?

Unusual sleep patterns Usually, we can give a simple definition of sleep: closed eyelids and specific brain wave patterns in the neocortex of the brain, which is why it is easy for us to judge whether mammals and birds have fallen asleep. However, this judgment method does not apply to fish.

Fish have neither eyelids nor neocortex, and their sleep can only be determined by behavior observation. When a fish sleeps, it has the following three characteristics:

(1) For a long time.

② Tail drooping

③ The sensitivity to the environment is decreased.

These three characteristics are suitable for most fish, but different kinds of fish sleep in slightly different ways. Tilapia will sink to the bottom when sleeping; Catfish keep an angle of 10 to 30 degrees with the bottom of the water, and sleep with flat tail and extended fins; Perch will sleep around logs; Coral fish will hide in the ravines of coral reefs to rest.

No matter which way you sleep, after fish fall asleep, their heartbeat and breathing frequency will decrease, and their mouths, cheeks and eyes will also reduce their movements. Fish researchers have done research, and there is a shark whose sensitivity to the environment has dropped to a very low level when sleeping, even if they hold themselves to the water, they don't notice anything.

Fish also have night owls, daydreams and sleep supplements. Although all fish need sleep, there are always some other types of fish that lack sleep. They sleep, but rarely. Who are mackerel and herring? Fish that swim all day? Although delegates swim less at night than during the day, they are on high alert 24 hours a day. There is also a horned shark, which is an out-and-out night owl. Night is more active than day, but it is also in full swing 24 hours a day. In fact, their sleep is like daydreaming, between dreaming and waking.

Some fish show no signs of sleep when they are young, but they will form sleep patterns when they are adults; Some crested fish suspend all sleep during migration and spawning.

Researchers usually observe the water surface of fish through tank experiments. In a previous study, researchers interfered with the sleep of fish by constantly tapping on the water tank and playing noise, which lasted all night. The next day, all the fish began to catch up on sleep. The frequency of their mouths and gills is nearly half less than normal, and they basically have no response to the stimulation of the external environment.

It's not just fish. So far, scientists haven't found any animals that can't sleep at all. They may sleep little, but they can't help sleeping.