Sharks are undoubtedly the ultimate apex predator of the sea. These terrifying, albeit magnificent, creatures patrol all five of the world’s oceans, found in both shallow and deep water.
Some are even known to inhabit freshwater rivers and lakes, making virtually any area of water ideal for a shark.
However, while we know that sharks are the leaders of the ocean, can sharks breathe on land?
Surely, with over 1,000 species of sharks present in the world, there must be at least one species that has adapted to life out of the water, right?
Whether you’re a budding marine biologist or if you’re simply curious about one of nature’s best apex predators, you’ve come to the right place.
Here is everything you need to know about whether sharks can breathe on land!
So, Can Sharks Breathe On Land?
Let’s get straight into it. The answer to this question is: no, sharks cannot breathe on land.
All shark species are aquatic animals, meaning they require water (whether freshwater or saltwater depending on the species) to survive. This means that there is not a shark that can breathe out of water.
The reason why sharks differ from terrestrial animals (which are animals that possess lungs and survive on land rather than water habitats) is because sharks don’t have lungs.
You read that right – sharks don’t actually breathe like other animals, because they don’t have a pair of lungs!
How Do Sharks Breathe?
So, if sharks don’t have lungs, how do they breathe?
Sharks, as with the vast majority of aquatic animals, don’t rely on a pair of lungs to breathe. Instead, sharks get their oxygen intake from the oxygen levels in the water around them.
So, while they still technically breathe and rely on oxygen to survive, they don’t inhale and exhale like terrestrial animals.
Instead, sharks rely on their gills to breathe. The oxygen levels in the water are far lower than the oxygen levels on land, so they use their gills to take in water, extract the oxygen, and then emit the carbon dioxide.
This is known as obligate ram ventilation.
All gills are fitted with small capillaries, which work kind of like a filtration system that separates the oxygen from the water.
Here, the oxygen can be directed into the shark’s bloodstream, allowing for oxygenated blood to pump around the body. The newly oxygenated blood enters the heart and leaves at the gills, wherein carbon dioxide is released.
Sharks will typically maintain their oxygen levels by swimming through the water, allowing water (and therefore oxygen) to flow in and out of the gills.
Some sharks are able to hold water in their cheeks and pump it through their gills while they sleep on the ocean floor, such as nurse sharks.
How Long Can Sharks Survive Out Of Water?
So, if sharks don’t have lungs (and instead have a more complicated way of breathing), how long can they survive out of water?
In the same way that humans don’t immediately die when they are in water, sharks don’t immediately die without water, either.
The answer to this question depends on a variety of factors, including the size and species of the shark. Some sharks will survive only a matter of minutes, while others might survive for up to an hour out of water.
Sharks are a highly adaptable species, so it’s unclear whether some species have learned how to survive with minimal oxygen intake.
As mentioned before, some sharks are known to hold water in their cheeks to provide oxygen for their bodies, but at some point the oxygen levels in this stored water will run out.
It’s worth noting that while the oxygen levels are significantly higher on land compared to in water, sharks will still not be able to consume this oxygen.
This is because sharks “breathe” through their gills, which rely on moving water to pass oxygen through their bloodstream.
It’s also important to point out that sharks might not survive when they go back into the water after being on land.
So, if you see a stranded shark on the beach and help it get back into the water, there’s a chance that the shark might unfortunately die in the ocean.
This is down to the gills. When a shark is out of the water, the gills will flatten and stick on top of each other, which is a function designed to prevent the overwhelming passage of gas resulting in hypoxia.
The gills might not open fast enough for the sharks to oxygenate themselves when they’re in the water, which can lead to deaths.
However, it’s not just breathing that’s an issue when sharks are out of water. Sharks release stress hormones when they are threatened, which helps to raise blood sugar levels during a fight or struggle for survival.
This, matched with a lack of oxygenated blood, can result in their death when on land.
The Case Of Epaulette Sharks
When we talk about sharks not being able to survive on land, there is a slight exception to the rule.
A species of long-tailed carpet sharks, known as epaulette sharks, are famous for their ability to walk on land in order to get to another area of water.
Epaulette sharks are nocturnal hunters that reside in shallow waters, such as tidal pools and coral reefs.
These sharks have learned to deal with hypoxia (severe oxygen depletion) by shutting down their non-essential neural functions and increasing the blood supply to their brains.
This means that these sharks are capable of surviving in anoxic waters for up to 2 hours with no negative effects.
Not only this, but epaulette sharks have utilized this unique skill by moving on land between tidal pools and shallow coral reefs.
Of course, epaulette sharks don’t exactly “walk” like humans. Instead, they will wriggle their way with their pectoral and pelvic fins between tidal pools without risking their lives.
Matched with slowing down their heart rate to preserve their oxygen levels, and you’ve got yourself a shark that can technically walk on land!
It is safe to assume that one of the reasons why epaulette sharks have this unique ability is partly because of their size. Epaulette sharks don’t typically exceed 35.5” in length, meaning they are often seen as prey for larger sharks.
So, with a smaller body to account for, these sharks don’t need to oxygenate their bloodstream nearly as much as larger sharks, such as hammerheads or great whites.
The reason why epaulette sharks often need to get out of the water is purely down to natural causes. As they hunt at night in shallow waters, they need to find shallow tide pools that appear as a result of a low tide.
This is because tide pools trap a range of marine wildlife, limiting their oxygen levels by 80% and resulting in the death of multiple fish.
So, epaulette sharks work alongside this natural cause by crawling into the tide pools, eating their prey, and then crawling out to find another tide pool.
As they’re so used to existing in anoxic habitats, they do not suffer in the low oxygenated tide pools, unlike the trapped marine wildlife.
Do Sharks Need Oxygen To Survive?
As with most animals on the planet, sharks need oxygen to survive – but this doesn’t mean they need air to survive.
There are lower oxygen levels in the sea compared to on land, but the oxygen in water is enough for sharks and other species to survive.
The only difference between how sharks and terrestrial animals breathe is that sharks don’t have lungs. So, with a lack of lungs, they don’t need the oxygen in the air to survive.
Instead, they rely on their gills to sift through water for oxygen, which then is pumped around the bloodstream.
Without oxygen, sharks will ultimately die. Lack of oxygen is known as hypoxia, which can lead to brain damage and the death of a shark.
Why Can Dolphins Breathe Air But Not Sharks?
Sharks and dolphins are often compared when it comes to their breathing processes. It’s important to remember that sharks and dolphins are completely separate species, meaning they have different ways of breathing.
Unlike sharks, dolphins actually have lungs that they use to breathe, just like humans and other terrestrial animals.
This is why they characteristically leap out of the water before submerging back into the water for 8 to 10 minutes at a time.
Sharks, however, don’t breathe in the same way as dolphins do. So, if you ever see a shark launch itself out of the water, this is likely for another reason – such as catching prey like birds or seals.
What Happens If A Shark Stops Swimming?
Sharks rely on their gills to breathe, and the gills rely on moving water to pump oxygen through the bloodstream.
So, if a shark stops swimming, they cannot receive the oxygen to survive, meaning they will ultimately die.
However, this doesn’t count for every shark species. Some shark species that are bottom dwellers, such as nurse sharks, have the ability to store large amounts of water in their cheeks while they sleep on the ocean floor.
They will then slow down their heart rate and turn off non-essential neural functions to survive on the limited oxygen levels in this stored water.
So, while some sharks have to constantly swim in order to survive, others have adapted to a non-swimming lifestyle between hunting periods.
If you’re wondering how other shark species sleep if they rely on moving water to breathe, this is because those shark species will slowly swim through water while they sleep.
So, there you have it! Sharks cannot breathe on land due to their lack of lungs. As they rely on the oxygen in moving water, they cannot survive on land for longer than several minutes to an hour.
Of course, there is a slight exception with the epaulette shark, which has adapted to low-oxygenated habitats to survive and hunt.
While these sharks can technically “walk” on land, this cannot be said for every other shark species.