Why don't ocean going mammals need to drink fresh water like other air breathing warm blooded animals?

Answer 1

Water Equilibrium of the Body: Despite the fact that marine mammals live in sea water, they rely on fresh water to survive. They can not satisfy their water requirement with salty ocean water. Although there is not a very clear idea about the fresh water resources of marine mammals, it is assumed that these animals feed on other marine mammals which carry only 1/3 of the salt the ocean has in their metabolisms. As it is seen, the sources of fresh water for marine mammals are scarce.

That is why it is compulsory for the marine mammals to use the water resources very carefully. It is interesting that marine mammals have an advanced mechanism of saving fresh water which is very similar to the mechanism typical of camels living in deserts. Just like camels, marine mammals do not perspire. Furthermore, for maximum water preservation, their kidneys produce very concentrated urine, much concentrated than the one produced by human kidneys. This is a very effective way of saving water in the body.

Water preservation is the utmost issue that reveals itself in every aspect of whale’s life. For instance, mother whale feeds its infant with a type of milk as dense as cheese. This milk contains ten times more fat than human milk and no sugar at all. There are some chemical reasons regarding why this milk is so fatty: during digestion of the fatty milk in the infants’ body, water is produced as a by-product. In the meantime, mother whale milks its baby with the minimum water loss.

Answer 2

There are special system in the ocean going mammals that processes the sea water to separate the the water and salt. Their liver filters their blood to get rid of the extra salt ( sodium chloride) better than the human lives. Furthermore their kidneys are able to produce very concentrated urine.

This is because the ocean going mammals are well adapted to their environment. Adaption can also mean changes in behaviour, diet and habitat to suit its environment.

Answer 3

These large ocean mammals use their food to get fresh water. However they also can absorb water as we do. We cannot absorb salt water because water is drawn to a more salty area. This is why when using water colors, if you put salt on the picture, it will absorb the water and color leaving the area lighter or white again. This is also why we need to have salt in our diet. When we eat salt on food we are able to put that salt into our cells which will help to draw more water into them the next time we drink. However, if we drink salt water it will be more salty outside of the cells, and therefore the cells will dry out. Large mammals like whales and seals are able to deal with this higher salt content in their water because they themselves have a high salt content. It is not a matter of salt or no salt, it is a matter of which has MORE salt. Since their bodies have more salt within the cells, they are able to absorb water from the salty sea.

Answer 4

Marine mammals aren't the only ones that do not drink - kangaroo rats are another example. All of these animals attain their water through their food and by retaining water produced through metabolism with kidneys that produce very concentrated urine. The link has a complete (but very detailed) description:

Answer 5

Their bodies process the water and salt differently then our bodies do. Most creatures adapt to their environment.

Answer 6

'cause they would die if they had to find fresh water!