Answer:
A mysterious, fantastic creature, It has one defining feature, And for humans at their worst, In their eyes it's just a horse
They swim around in schools or pods and they are related to whales
They're actually great swimmers now, but later they will become excellent hoppers.
I have a powerful bite and live in rivers and swamps. People are often afraid of my big jaws. What am I?
What has a horn but does not work?
You use it between your head and your toes, the more it works the thinner it grows.