As is known, a person cannot survive long without water, but how do dolphins manage this? If they do not drink seawater, as their kidneys would fail due to excess salt, then where do they get fresh water in the sea?
Despite being mammals, they still need water, which they obtain from the fish they constantly hunt. This means that to quench their thirst, they need to eat. Therefore, in aquariums during training, they are not restricted in rewards: if a dolphin does not follow a command, it is retrained rather than having its treats reduced. Otherwise, it will start to feel thirsty while in saltwater, which is a dangerous condition for its life.
However, in their natural habitat, it may theoretically happen that there is not enough fish for everyone, so nature has provided another "channel" for obtaining water: a dolphin's body can generate it by breaking down its own fat. Moreover, this happens at a very favorable "rate": one gram of fat turns into four grams of water.
Is it true that dolphins save drowning people?
In fact, this is one of the beautiful tales based on how dolphins help their kin. If one of them is sick or injured, the group tries to help it in every way, keeping it afloat so it can breathe. A wild dolphin, however, finds a human neither interesting as a "kin" nor as prey. Moreover, there is not a single officially recorded case of a dolphin saving a human, and all existing stories are based on emotions, exaggeration, and insufficient knowledge about dolphin behavior.
In general, a dolphin may swim up to a person to play (which would be a downside in the case of drowning) or ask for food – if the animal has escaped from an aquarium and associates the person with someone who has fish.
Such myths also include stories that dolphins heal people. Allegedly, their echolocation has a positive effect on the human body. However, the entire therapeutic effect boils down to the psycho-emotional state: some need to swim with dolphins, others want to feed a squirrel from their hand, some wish to treat a horse with carrots, and for some, simply petting a cat is enough to lift their spirits and feel better overall.
