Sharks are fish, the other three are mammals.
I'm not entirely sure(I used to have a heifer who liked to eat everything she wasn't supposed to) but I think cows are herbivores while the others are not.
The "killer whale"(which is an Orca, and closer to a large Dolphin than a whale) is the only one that has echolocation.
The rat is the only scavenger on the list.
Probably not helpful, but it's all true.