Is a seal a mammal Seals live in the water and are aquatic animals, but they can sometimes come to shore and stay for a long time. Some people mistake seals for fish because they live in water like fish, and for amphibians because they can live on land as well as in water. In fact, seals are mammals, a higher level than fish and amphibians. Seals lived on land a long time ago, and then they lived in the water because of changes in their living environment, but this does not change their nature as mammals.
As a mammal, seals have some outstanding characteristics, which are different from those of fish that also live in the water. For example, seals use viviparous reproduction, and there is a lactation period after production, which is very different from fish. For example, seals use lungs to breathe, which is one of their outstanding characteristics, which makes them stay on land for a long time.
In addition, from the point of view of body structure, since they can live in water, there are naturally some special structures that can be regarded as their outstanding characteristics. For example, their bodies are streamlined, and their limbs have become more and more like fish fins over the long course of evolution, allowing them to swim freely in the water. Also, under their skin is a thick layer of fat, which not only keeps them warm, but also gives them enough buoyancy in the water so that seals don't have to work so hard when they swim.
