Sea creatures are something that fascinate almost all of us from an early age — take any child to an aquarium and they will let you know. The knowledge that we have on these creatures, however, can be shockingly limited. Studying whales and other animals that have migratory patterns that cover huge stretches of water and difficult seas can make it almost impossible to get real in-depth information.
This leaves many questions for us, but a pretty common one is: do whales drink water?
While we don’t know the answer to this question for most marine mammals, we do know that whales, in fact, drink water directly from the ocean. Considering that we are both mammals, you may be wondering why it is that whales can do this, but we can’t. One factor that plays into this is our kidney. The kidneys act as a filtration system for our body: All the water in our body passes through these kidneys where waste and excess water is filtered out into our urine.
The Process to Filter out Sodium
A driving factor in how much water is released out of our blood system is salt (which is one of the reasons a high sodium diet can be bad for you). Therefore, if you drink salt water the high levels of sodium will drive water out of your system when you need it to stay, causing you to become severely dehydrated. Our kidneys are not equipped to drink salt water, but whales’ kidneys are. The massive size of the whale’s kidney and its efficiency allow it to filter out the salt without sacrificing the water their bodies need.
One way scientists think this is happening is by having either more efficiency in preventing excess water from being secreted through the glomerulus and/or that there is more water being reabsorbed in the loops of henle. A glomerulus is a part of the kidney’s filtration system that has slits that allow small molecules and fluid to pass through while keeping some fluid and blood cells in the circulatory system. The loops of henle are another part in which right before the fluid is carried to the bladder the body has a chance to reabsorb some water.
Humans rely on salt to do this, so it is still somewhat of a mystery as to how whales do this without reabsorbing massive amounts of salt. Humans also lose water in lots of ways that whales do not such as sweat and even breathing. Whales have the advantage of living in water and therefore do not have the need to sweat and they obviously do not breath in the same way we do so they lose less water. Another advantage is that the foods that they eat, unlike the ones humans are drawn to, have virtually no salt in them which prevents them from putting any additional strain on their kidneys.
A more passive way that whales (and other animals who don’t have amazing kidneys) are thought to get water is through their prey. During digestion one of the by-products is water so when eating their prey their bodies are able to absorb the water content from the breakdown process. This is called a metabolic breakdown and humans do this too!
Sea lions and other similar mammals are thought to use the same super kidney process to excrete extra salt while retaining the maximum amount of water. Now while it’s essentially impossible to measure in whales, when looking at the amount of salt excreted in their urine it was higher than the amount of salt in the water that they drank and almost ten times the amount of salt as their blood!
As resources grow, the public can continue to learn more about whales and other sea creatures. The interest has always been there, but technology is just now starting to catch up. Hopefully, this will lead to a plethora of new knowledge on these amazing creatures.
To learn more about whales, visit our other posts. There, you can learn how to identify different types of whales, what a blowhole is and how it works, and so much more!