I've seen a bunch of crabs in a bucket before and it does look like they experience selfishness. They love to grab at anything they can to get to the top before anyone else, but it almost always works against them. I think I read one time that this is called crab mentality.
This is interesting, indeed. However, to be fair to our crabby friends, I do not think that crabs behave like this out of selfishness; in fact, I do not believe that they have the ability to have such a pattern of behavior stemming from a mental thought process, in the first place.