only speed boats and humans if not careful
Boats
Mainly motorboats.
it has no natrual enemies
No. Manatees live in tropical and sub tropical regions, not in the Arctic.
Boats - propellers kill more manatees than any other predator.
humans
They don't react to their enemies. They remain in shallow waters to avoid danger.
humans
yes they do, they are fish,and sharks,or whales.
they don't need to because they have no natural enemies
There are no natural enemies of the manatee for they do not share waters with sharks. One of the unnatural enemies are motor boats!