How sharks sleep

According to experts, sharks (or sharks, as they are also called) have been around for more than 450 million years. There are many curious and interesting facts about sharks, such as that the whale shark is the largest fish in the ocean, that sharks replace their teeth throughout their lives or that they have very strange sleeping habits.

If you like animals or you are simply a very curious person, do not miss the following article, because below we explain how sharks sleep and we reveal everything you need to know about this fish.

How sharks sleep

The truth is that, in reality, sharks do not sleep, at least not as we understand the being’s human. What sharks do is rest, so that only part of their brain is unconscious when they perform such an action. In fact, and closely linked to this, we must mention that most species of shark’s rest moving, because sharks have to be in constant movement to be able to breathe.

On the other hand, there are species of sharks such as the nurse and catfish (remember that there are approximately 465 species of shark) that can stay still and continue breathing, something that is due to their ability to absorb water by mouth pumping. But this does not mean that they can sleep soundly as we humans do, because they need a certain degree of consciousness to be able to breathe.

In turn, it should be noted that the white shark has been seen sleeping or resting in a relaxed and calm way, but without stopping moving and with its eyes open. This is because the white shark, also called the “king of sharks” or the “great shark” has certain special characteristics:

• On the one hand, this shark has a highly developed sense of smell and is able to detect blood residues and other elements several kilometers away, so you should always be vigilant.
• The same goes for movement, as the king of sharks can perceive any movement in the water several meters away.
• In addition, we are talking about a fish with very sharp scales that allow it to move extraordinarily quickly through the water. In fact, it can reach up to 50 km per hour when it comes time to hunt.

Why sharks sleep swimming

Most sharks, when resting, must keep moving. But why do they take these rest periods in constant motion? The easiest explanation is that sharks do not possess a swim bladder like many other fish, a buoyant organ that allows them not to sink.

In addition, in order to breathe, sharks must have their mouths open and thus absorb the necessary oxygen that passes through their whites. These gills only absorb oxygen when the shark is in motion, something that also explains why these fish sleep swimming.

On the other hand, it is worth mentioning that there are species of shark that have spiracles. These are openings behind each eye that cause water to move through the shark’s gills, allowing the fish in question to rest and not move on the ocean floor.

Why sharks sleep with their eyes open

To begin with, you should know that there are sharks that do not even have eyelids, because the sea water is responsible for washing their eyes at all times. However, there are sharks that have a tans lucid membrane (or Nictitating membrane) that allows them to keep their sight protected when swimming at high speed, when they attack or when they are attacked.

However, we can also say that if sharks sleep with their eyes open it is because, remember, they are not really asleep, but a part of their brain is still conscious to continue with the cycle of taking air and resting at the same time.