First of all, fish sleep with their eyes open. Many fish make up vulnerable groups in the ocean and can fall prey to predators if they are not careful. The poor little fish barely had time to sleep to save his life. Sometimes I can sleep for a few minutes, sometimes I can only sleep for a few seconds. In other words, after blinking a few times, the little fish fell asleep. Since it has no eyelids, the fish cannot close its eyes even when it sleeps.
Second, unlike dolphins, seals can sleep underwater or on shore. Interestingly, when they sleep underwater, they stick their noses out of the ice caves to breathe, and their body floats vertically in the water, resembling a vertical sculpture, which facilitates ventilation without delaying deep sleep. As the largest animal on the planet, thes whales sleep in a very interesting way. Whales generally sleep while floating on the surface of the water. While sleeping, they will form a circle around the whale's head and sleep in a radial pattern. Some whales will stand in the sea, sleeping with their heads up and tails down.
Also, when parrotfish sleep, they secrete mucus from their mouth to form a bubble sleeping bag to wrap themselves around. This is done to isolate odors and protect against olfactory predators such as eels. In accordance with the principle of frugality, they will eat the sleeping bag when they wake up and reuse it next time. The garden eel, which is commonly found diving, is a very vigilant fish. Their body length is usually 30 to 40 centimeters. Usually, they bury most of their body in the sand, leaving only about 10 centimeters expdared. When they sleep, they bury them all in the sand to protect them from predators.
What you need to know is that marine animals need long periods of rest. In a particular and open environment like the ocean, marine animals must be vigilant at all times to avoid being swept away by currents and eaten by their natural enemies. Therefore, they cannot have long periods of rest like humans, nor can they sleep in a fixed location, making the sleep activities of marine animals difficult to detect. But if you look closely, you will find that the way marine animals sleep is really interesting.