Senior Editor
Staff

The Inertia

A lot of people think that sharks don’t sleep. And while that’s partially true, it’s only true because they don’t sleep in the same way that we do. Many types of sharks, as you likely know, need to keep moving to stay alive. They require the movement of water over their gills to get oxygen. There are a few ways they do it.

“These kinds of sharks are known as obligate ram ventilators because they draw water in through their mouths and force it out through their gills,” Don Vaughan wrote for Britannica. “Many sharks use a method called buccal pumping, in which water is pulled in through the mouth and forced out through the gills by the cheek muscles. Other types of sharks are able to remain stationary because they possess special structures called spiracles, which force water through their gills. Some sharks use both spiracles and buccal pumping.”

If any of these types of sharks stop swimming — if, say, they were caught in a net — they would end up suffocating. According to Britannica, some sharks, like the whitetip reef shark, the Caribbean reef shark, the nurse shark, the wobbegong, and the lemon shark, can rest while remaining stationary. But whatever method they use to get that oxygen, sharks do “sleep”, at least in a sharky sense of the word. While they don’t lie down in bed and stop moving like we do, they have periods of deep rest. Since sharks don’t have eyelids, they can still keep an eye out while they’re in that state of deep rest.

It’s hard to tell, though, whether a shark is “sleeping” or whether it’s just swimming lazily around in circles. But Carlos Gauna, the drone operator/amateur shark expert who shot the video you see above, thinks that he might’ve caught a great white shark snoozing— and if he did, it looks as though it had a rude awakening when two stand-up paddleboarders interrupted its nap.

 
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