No, it was (apparently) not described correctly anywhere else. But what you see in the most recent game is the highest canon. You get what you see, not what you read.
Cyrodiil's fauna matched its environment. It wouldn't work to put strange monsters everywhere that didn't match the environment.
Exactly what did you want them to be? They're crabs, so Bethesda made them look like RL crabs. Only bigger.
Just by the way, if you felt the need to focus on my spot, because I sued yours above, then I wasn't attacking your statement, I was being sarcastic about the game.
However, to me, Oblivion did not represent Cyrodiil correctly, and what you see is something that has been rather selfishly compromised for the mainstream market. The highest canon, is what is written, because what is written is what goes into the games, not the games themselves.
Cyrodiil's fauna matched it;s environment in what context? It didn't because you can't define anything to suit it unless it's based on real world, and even then Land dreughs seem out of place.
And as for mud crabs, yes, I expect them to be crabs used to swampland and mangroves, (like the Imperial City was supposed to be surrounded by) not having coral growing on their shells.
I think I am only being fair in that.