There are Bull sharks in Lake Nicaragua which have been there for generations. I don’t know of any Snapping Turtle or Muskie that can remove someone’s leg, it had to be a Bull.
“There are Bull sharks in Lake Nicaragua which have been there for generations. I dont know of any Snapping Turtle or Muskie that can remove someones leg, it had to be a Bull.”
I don’t know this first-hand, but the evidence is that Lake Nicaragua is open to the sea. According to the Wikipedia entry for Bull Sharks there have been specimens tagged in the lake that were later found in the ocean and visa versa. Also, on the discussion of their evolved ability to tolerate freshwater there seems to be a definite limit when it comes to adult sharks. That they will eventually die, if only by starvation. But there may also be limits on toleration place on them via the functioning of key internal organs (ie. kidney & liver) that would kick-in long before starvation.
The theory is that Bull Sharks evolved to tolerate freshwater as a breeding-survival strategy. They go up into brackish water to have their pups, then move back into the estuary/sea. The pups grow up in freshwater, away from predators, and eventually move down to saltwater as they mature.