Sharks can drown

Is it true that sharks can only breathe when they are moving?

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Is it true that sharks can only breathe when they are moving?

Many things are said about sharks that are not true. They are also said to suffocate if they do not move. Is that correct and if so, why is it so? Tom from Rostock sent us this question.

Yes, it's true, but only for the deep-sea sharks. Deep sea sharks must always keep moving so that they do not suffocate.

In principle there are two types of shark: those of the deep sea sharks and those of the sharks that live near the bottom or in reefs.

Deep sea sharks also sleep while swimming. They mainly use their drive to breathe. They swim with their mouths open. This allows the water to flow through the pharynx into the gills. The oxygen is withdrawn from the water and released into the blood. The water exits through the gill flaps. So ocean sharks don't move their mouths to breathe. If they did not swim, no fresh water with fresh oxygen would get into their bodies, they would suffocate or drown.

The sharks, on the other hand, which live near reefs or near the bottom, alternately close and open their mouths. This creates a suction. So you take care of the inflow of water yourself. Sand, nurse or carpet sharks can lie buried in the sand for hours.

First they close the gill flaps, then they suck in water when their mouths open - as if they were eating it. Then they close their mouths again, open the gill flaps and press the water out again. During this process, they extract the vital oxygen. Such reef sharks can sleep in the sand or in caves without having to swim all the time.

Ocean sharks, on the other hand, are constantly forced to swim so that enough water flows over their gills and their oxygen needs are met. This is why these sharks suffocate if they get caught in fishing nets.

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