They are known as amphibians.
Amphibians
plants and animals that live on land are called terrestrial animals plants and animals that live in water are called aquatic animals
Call the samething like a mammal. It depends if it lay eggs or give birth.
they are reptiles, reptiles can survive both water and land.
Amphibious
Beavers live on both land and water.
Amphibian
semi-aquatic
Amphibians.
I think what you are asking for is amphibian. An animal capable of living both on land and in water.
You can call it anything you want!
Amphibian