The animal kingdom is fascinating, and in it we find fish , which are home to a multitude of curiosities. Although many species of fish are well known to us, such as sharks, they have some characteristics that continue to surprise us. Something that has always drawn a lot of attention to fish has to do with how they sleep and their sleep cycle.
Do fish sleep? Most curious features
Surely on some occasion you have wondered if fish sleep, or on the contrary, they spend their entire lives swimming in the deep sea, without resting for a single second. Well, just like humans, they need to reduce their physical activity for a few hours a day. Now, fish do not have eyelids, so when they sleep they do so with their eyes open. This is the main reason why some people think they don’t sleep, but they really don’t. Fish have a membrane that covers their eyes, which prevents the dim light at night from disturbing their rest in any way.
Scientists estimate that there are 28,000 species of fish in the world , and each one has specific characteristics when it comes to sleeping. Some sleep putting their lower or rear fin on the seabed as an anchor so that the sea current does not drag them away. Others, on the contrary, make a series of strange noises so that predators do not approach them.
One of the most surprising techniques is the one used by some fish. It consists of dropping to the bottom of the seas and oceans and, thanks to its swim bladder, rising to the surface to breathe , and then going back down to the bottom. All without waking up!
Another resting technique that some fish use is to drop to the seabed and thanks to their swim bladder they can go up to breathe and go back down to the bottom without waking up (yes, although it sounds incredible).
What whales and dolphins, which are mammals, do is stay completely still if they are alone. On the other hand, if they are accompanied, one is in charge of acting as a guide, while the rest swim very slowly beside them.
What about sharks ? They don’t have a swim bladder, so they can’t go up to breathe. Therefore, they have to be constantly moving in order to breathe, even when they sleep. If a shark stops, the risk of going to the seabed and dying is very high.
In short, fish do sleep , although they do so in a very different way from ours.
