Do Whales Drink Water?

Whales live in water, and like all mammals must take in water to survive.  This got me wondering if they drink seawater, and if so, how they manage to survive drinking seawater.

Whales get most of their water intake from their diet of fish.  They do also drink seawater, as their kidneys have adapted to be able to filter out a lot of the salt.

I wanted to find out some more information, and I am sure you will be interested in what I found out.

Do Whales Drink Water?

In most cases, marine mammals such as whales do not directly drink water from the sea. Water is supplied through the metabolism of protein from the prey, and from the oxidation of fat. 

This means that marine animals do not drink water as a land animal would. Marine mammals get their intake of water through their food. Marine mammals prefer to eat fish.

The amount of water they intake depends on what species of fish they feed on. Some species of fish have more water in them than other species.

A female whale when pregnant feeds typically on different species of fish than a non-pregnant whale would. A pregnant whale would feed on fish that have a high amount of protein and fat for the calf growing inside of them. 

After the calf is born, the female whale tends to change their diet to a fish with higher water content. This food allows the whale to be able to produce milk for the calf. All species of fish will provide some water as part of the whale’s diet.

Whales live and spend all their time in seawater. The whale’s bodies need water to survive, and scientists assume that whales do drink some seawater.

The blue whale takes up to 10,000 gallons of water into the mouth while eating in the sea. However, they do not drink all of that water, but it will drink small amounts of it. 

The mouth of a baleen whale filters the food through the baleen and then pushes the water out, but it will still take some seawater through. 


Whales need less water than other mammals needs. Whales live in an environment surrounded by water. Because of this, they lose less water to their surrounding compared to land mammals. Whales do not sweat like a human, or other mammals on land do. Thus they will lose less water from their bodies. 

If you have ever wondered how whales eat, I have written an article which you may find interesting here.

Do Whales Drink Sea Water?

Whether whales drink seawater is one of the questions that scientists have tried to tackle over the years.

There is one conclusion that whales do take in seawater but only in small quantities. This conclusion is anchored to tests on whales urine concentration.

Whales produce urine with an osmolality higher than of seawater. Osmolality tests how much substances such as sea salt have dissolved in urine.

It is believed that marine mammals such as whales drink seawater because their urine contains more salt than seawater. It is assumed that the urine of a whale is primarily composed of sodium. 

Harbor seals also take in seawater, although this is due to feeding underwater.

Gray whale

If you have ever wondered why whales migrate, I have written an article, which you can find here.

How Do Whales Filter Salt out of Seawater?

Whales take in seawater, and this means they have a high sodium concentration. When you take saltwater in, it means you are receiving high levels of sodium into the body.  

This is not healthy and will lead to severe hydration and can result in death. Due to the massive size of the whale’s kidneys, their efficiency allows the whale to filter out the salt without sacrificing the water their bodies require. 


Scientists believe that whales filter salt water from their bodies. They do this by reabsorbing more water into the kidneys.

The studies on salt urine concentration tell us that whales filter seawater after taking it into the body. Whales are said to use their large kidneys to process and excrete the extra amount of salt while retaining the maximum amount of salt needed. 

It is not easy to measure the amount of salt excreted, but their urine gives the answer. It has been found that whale urine has a higher amount of salt than the water they drink. The urine is ten times as salty as their blood. 

How Does the Kidney Function of a Whale?

The kidney of a whale is built to regulate the salt they take in through the seawater. Marine mammals such as whales are well adapted to their environments. They live in salty water and have no other option but to take the saltwater in when feeding.  

Whales can succeed in this environment as their kidney structure is unique. Some differences exist between the kidneys of a marine and terrestrial mammal.  

These differences are an indication that their specialized kidney allows them to occupy habitats with a broad range of salinity. The kidney is the principal organ of water and electrolyte regulation.  

The kidney of a whale has increased thickness necessary to produce highly concentrated urine. This is important for mammals living in a hyperosmotic environment. 

gray whale

Whales have a multi-lobed kidney. The kidney has an increased surface area for removing toxins from the body more efficiently than a non-lobed kidney.  

Whales typically regulate their water balance by metabolism and only drink seawater occasionally to maintain the balance of salt in their bodies.

Ever wondered why whales come so close to shore. You can find out here in an article I have written.

How Do Whales Ingest Water?

Water is essential to any living thing and is just as important to whales. They acquire water from the food they ear after metabolism takes place. Whales chose what to eat to ensure they get enough water from their food. 

Whales also drink seawater but only occasionally. They have a large kidney to remove the salt from the water, without losing the amount of water. 

Researchers can measure the amount of seawater ingested by organisms using isotopic tracers. These tracers are atoms that are introduced or already present in water. These atoms can be differentiated and detected due to their mass. 

Researchers add the amount of water ingested by food intake and metabolism to make a comparison of the amount of total water passed into the body. The difference between the two quantities gives them a good idea of the amount of seawater that a whale has ingested. 

Sperm whale

Whales breathe through the blowhole while they eat through the mouth. The separation helps whales not to consume water, which can accidentally enter into their lungs when consuming prey. 

In conclusion, whales need water to survive. Therefore it can drink seawater. Their large kidney can filter salt after taking in the water. The filtration system is more advanced in whales than land mammals.  

Whales also get their water from the prey it eats. Whales have adapted to know which fish give them the water they require at certain times. Whales also do not require as much water as other humans beings do, due to their lack of sweating. 

If you would like to know what the ten biggest whales are in North America, I have an article you may like. You can find it here.


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Bryan Harding

Bryan has spent his whole life around animals. While loving all animals, Bryan is especially fond of mammals and has studied and worked with them around the world. Not only does Bryan share his knowledge and experience with our readers, but he also serves as owner, editor, and publisher of North American Mammals.

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