I was born (出生) in a small river. When I was young, the river was my home. I did not know my father or mother, but I had many brothers and sisters. We always swam and played together with each other.
At that time I didn't look like my parents. I had no legs, but I had a long tail. So I looked like a fish.
Then my tail became shorter and shorter. And now I have four legs and a very short tail.
I know I'm going to have no tail at all soon. I'm going to be like my parents. Then I'm going to jump out of the water. After that, I can live both on the land and in the water. Who am I?