There are a number of reasons why dolphins can’t live on land.

First dolphins require a steady supply of fish and other aquatic species in order to survive.

In some cases dolphins may dive up to 700 ft. or more in order to find specific food which their body is used to and can easily digest.

If dolphins lived on land they would not be able to find the types of food they need to survive and if they were able to find food there is no guarantee that their body will be able to process the food because there is a good chance that their digestive system would not be familiar with it and may not be able to digest it properly leaving the dolphin malnourished and/or starving.

Secondly, dolphins need to stay hydrated in order to survive.

Anyone who has even seen a beached dolphin or beached whale knows how important it is for them to always be in water.

Most beached dolphins can only survive for a short amount of time (a few hours) on land before becoming dehydrated, especially in warm or hot climates.

Third, dolphins do not have the limbs necessary to walk on land and thus would end up becoming immobile.

Again beached dolphins often end up stuck on the sand and are unable to return to the ocean because they are incapable of walking on land or in the case of a beached dolphin back to the ocean.

Fourth, while this may not apply to all species some dolphins such as the killer whale are extremely heavy.

After a few minutes of being on land a large dolphin may end up having difficulty breathing due to its massive size.

In water dolphins are provided with buoyancy and do not have to worry about their weight the way humans do, but once they are on land gravity has the same affect on them as it does with all land animals.

Since dolphins and whales are marine mammals and live exclusively in the ocean they have not developed the muscles that are necessary to sustain themselves on land.

Reasons why dolphins can’t live on land

Dehydration

Heat

Immobility

A lack of food

Difficulty breathing

But what about their ancestors?

Interestingly, the earliest ancestors of whales and dolphins did live, hunt and survive on land.

They also had limbs used for walking (bones can still be seen in the flipper of cetaceans) and their spine appear to have been designed for traveling on land as opposed to in the ocean, which is why dolphins arch their backs and flukes when they swim instead of moving from left to right like fish.

Then there’s the fact that whales, dolphins and porpoises are all mammal, breathe air and give birth to live young despite living exclusively in the ocean.

Again this is very different from fish that are largely cold-blooded, breathe through gills and lay eggs.

Over the course of millions of years cetaceans slowly evolved and took to the ocean in order to adapt and survive.

Their limbs became flippers and flukes, their nostrils moved to the top of their head (now they are known as blowholes) and they develop a thick layer of blubber to help them survive in the coldest climates.

All of these evolutionary changes took many millenniums to occur and eventually evolved these mammals into the ocean bearing creatures we now know today.

In order for dolphins to evolve and walk on land it would require millions of years of slow evolution and a steady habitat to ensure their survival.