Gills Or Lungs: Can Sharks Breathe Underwater?

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Sharks are some of the most optimized predators in the ocean. They have an exceptional array of senses that helps them identify and hunt down prey.

One aspect of sharks that often confuses people is how they breathe, or if they breathe at all. Unlike marine mammals, sharks get their oxygen from a different source.

Can sharks breathe underwater?

Yes, sharks get their oxygen from the water, allowing them to essentially breathe underwater. Like fish, sharks have gills that allow them to extract oxygen from the water, meaning they don’t need to surface.

Do Sharks Need Oxygen?

Although sharks don’t have lungs, they do have to breathe oxygen to survive.

However, unlike us humans and marine mammals, they don’t get their oxygen from the air, instead, extract it from water.

The concentration of oxygen in water is much less than in air, so sharks have developed ways to harvest as much oxygen as possible whilst underwater.

How Do Sharks Breathe Underwater?

Now we know that sharks don’t need to surface for oxygen, like whales or dolphins, can sharks breathe underwater?

Yes, they certainly can. It was once thought that sharks had to keep swimming all of the time to keep water moving into their mouth and out through their gills so that they could breathe.

Now it’s known that this simply isn’t true. Breathing in this manner is called “Ram Ventilation“, and it’s when sharks force water through their mouth, over the gills, and extract the oxygen.

Whilst this is the most efficient way for sharks to breathe, it does involve swimming, which would make sleeping and resting difficult for sharks.

Most species of sharks are able to rest on the bottom of the ocean and move water over their gills by simply gulping.

The Nurse Shark, White-tip Reef Shark, and Lemon Shark all practice this form of breathing which is called “Buccal Pumping“.

The shark’s gills work as a filter to extract oxygen from the water, and the oxygen is then passed into the blood and transported around the body.

The excess water is then pushed back out into the ocean through the shark’s gills. it’s a pretty impressive breathing system that allows sharks to breathe underwater.

Do Sharks Drown If They Stop Swimming?

Whilst many sharks are able to breathe through this method, there are some species of sharks, roughly two dozen which are called “Obligate Ram Ventilators“.

These sharks include the Great White, Bull Shark, and Mako Shark, these guys can only breathe by swimming through the water and ramming water into their mouths.

Meaning that if they stop swimming, they will literally drown. These are the species of sharks that must keep swimming in order to survive.

This is why so little is known about the sleeping patterns of these sharks. It’s believed that they are able to take short naps when they can find a current that they can gently swim along with.

This allows the sharks to get some rest and recharge their batteries for the day ahead, but they must stay on the move whilst doing so in order to breathe.

Can Sharks Survive Out Of Water?

The length of time a shark can survive whilst be out of water largely depends on the species as well as their size.

Some sharks can survive as long as 12 hours of being out of the water, especially sharks that typically live in shallow reef areas.

Whereas most large species of shark can not survive longer than a few minutes out of the water as they suffocate due to lack of oxygen.

Sharks have evolved to extract water using their gills, and given that they don’t have lungs they rely on the water to breathe.

Do Sharks Need To Surface For Air?

Unlike marine mammals, sharks do not need to surface for air. They get everything they need from breathing underwater through their gills.

Sharks can often be seen near the surface of the water as this is where they feed, but they are not coming to the surface for air.

When you see a shark’s fin sticking out of the water, this is an indicator that they are swimming near the surface to look around for any prey that it can feed on.

Do Sharks Drink Water?

Sharks are incredibly impressive animals, they get everything they need from simply being in the water.

They don’t drink water as land animals do, and instead are able to take all the water they need for hydration through their gills through osmosis.

This means that they don’t need to drink. They have a gland in their digestive system that then allows them to secrete any excess salt from saltwater.

They also don’t lose water the way bony fish do, their bodies stay in balance with the ocean in different ways thanks to a chemical called urea.

Essentially there is as much urea inside a shark as there is salt in seawater, allowing the shark to stay balanced with the saltwater outside of its body.

Final Thoughts

Sharks are exceptional creatures that are highly adapted for life in the ocean. They are unlike mammals in the fact that they do not need to surface for air and can breathe underwater.

This allows them to stay submerged and hunt prey, with them only really coming to the surface to feed or take a look around.

Sharks have gills, similar to fish that allow them to breathe through ram ventilation and buckle pumping.

These are processes where the shark forces water over its gills and extracts oxygen from it, then releases the excess water back into the ocean.

Hopefully, this post has been helpful and you have learned a thing or two about how sharks breathe underwater.

Thanks for taking the time to read this post and feel free to stick around to learn more about sharks and marine wildlife.