Cold knowledge, how do fish sleep, close their eyes?
Vertebrates have to sleep, fish are vertebrates, also need to sleep to eliminate nervous system and limb fatigue, however, fish do not have eyelids (eyelids) so it sleeps, can not close its eyes. We often see the fish standing still in the water, the gills moving in a flash, which is exactly what the fish is sleeping, and if you wake it up, it will swim in the water again
The way the fish sleep
Scenario 1: Sleep in the dark
A closer look at the goldfish we raise will reveal that they have arrived
Fish sleeping at night
At night, you will hide in the shadows such as small rockeries and aquatic plants in the fish tank and stay motionless. This is the state in which the goldfish sleeps.
Scenario two: Drilling in the sand
Some fish are like the pig fish of the flower sea; the slender longhead fish and the golden fish live at the bottom of the ocean, and when the night comes, they will burrow into the sand and sleep motionlessly, which is both quiet and effective to prevent the damage of natural enemies.
Condition three: Secretion of bubbles
Some fish such as split-billed fish, South Sea parrotfish, its body will secrete a special gelatinous substance, when they want to sleep they blow a large bubble like a child, the gelatinous bubbles meet the water hardening, and then they drill into the bubble, leaving only a small hole in the mouth, just like in the sleeping bag.
Most of the fish living in freshwater sleep behind rocks and in the shadows of aquatic grass. Carp and crucian carp burrow into aquatic weeds, while mullet and snapper sleep behind rocks.
Scenario four: swim while sleeping
Fish with migratory habits sleep while swimming. They swim non-stop because they have to constantly spit out water to keep breathing, such as sharks, tuna, mackerel, and chickadee, swimming back and forth day and night, making it difficult to figure out when they are sleeping and when they are awake.