a dolphin is a creature that lives in the water and is an aquatic mammal. They have been living in water for a long time. Although ancient dolphins may have had four limbs, they could walk and live on land. But after the environmental changes, the body structure of dolphins has changed greatly, their limbs have been degraded, and evolved pectoral fin, tail fin, dorsal fin and other body structures. In addition, their skin is kept away from water. These body structures make them suitable for living in water. Although dolphins can leave the water for a period of time, they can not leave the water for a long time.
In addition, not only can dolphins not leave the water, they can not leave the sea. If dolphins live in fresh water, their bodies may swell and their organs may be damaged to a certain extent. If you go on like this for a long time, you may die.
Although dolphins live in water, they are different from other mammals because they are a kind of mammal. Generally speaking, dolphins can not live on land for a long time. First of all, dolphins have no limbs, so it is very inconvenient to walk on land. Over the course of evolution, their body structure has made them suitable for living in water all the time. In addition to having no limbs, their skin structure also makes them unable to live on land because their skin has no way to leave water. It is not a problem to live on land for a short time, but it will adversely affect their health and even their life span for a long time.
Although we say dolphins can't live on land. However, as a mammal, dolphins need lungs to breathe. Therefore, they can not stay in the water all the time, but need to come out of the water regularly to breathe, just like whales.
