20.08.2026 – Thirsty in the Ocean?

“How do they drink if they are surrounded by seawater all the time?”

This was a question I was asked on todays tour and it’s actually more interesting than it might seem at first.

Whales and dolphins live in the ocean, but they can’t simply drink unlimited amounts of seawater. Their bodies have to deal with the high salt content of the ocean. Instead, a large part of the water they need comes from their food.

Fish and squid contain a lot of water. So when a dolphin or whale eats the prey, it is also taking in a considerable amount of water. During digestion, the body also produces what is known as metabolic water, which can be used by the animal as well.

But what happens to all the salt? The kidneys of marine mammals are specially adapted to remove excess salt from their bodies. This allows them to maintain the right balance of water and salt, even while living in a salty environment.

So, although whales and dolphins are surrounded by water every second of their lives, they don’t simply drink seawater whenever they are thirsty. Much of the water they need comes from the food they eat, together with the water produced by their own metabolism.

Sometimes, a simple question on a tour can lead to a fascinating insight into how these animals are perfectly adapted to life in the ocean.

by Malina Labowsky

Sightings of the day

Ribeira Brava 

09:00 Bottlenose dolphin, Short-finned pilot whale

13:00 Bottlenose dolphin, Atlantic spotted dolphin, Blainville’s beaked whale

16:30 Atlantic spotted dolphin

Steno 

09:30 Bottlenose dolphin, Short-finned pilot whale

13:30 Bottlenose dolphin, Short-finned pilot whale, Atlantic spotted dolphin

16:30 Bottlenose dolphin, Short-finned pilot whale, Atlantic spotted dolphin