[Alberta's Child]

Excellent points. It's worth noting, though, that every action of these animals (as far as we can tell, and we'll assume this to be the case unless proven otherwise) is directly focused on eating or mating (in other words, survival). Humans are the only species that will do something simply for the hell of it.

[spqrzilla9]

Humans are the only species that will do something simply for the hell of it.

Another false claim, many species do something "for the hell of it". Just as an accessible example, cats will toy with prey they have no intention of eating.

[Junior]

Humans are the only species that will do something simply for the hell of it.

Cats (including tigers) have been known to hunt and kill simply for the joy of it (not consuming the kill afterward). I often catch my cats and dogs playing with balls, pieces of string, or various small items that have fallen to the floor. My cats set ambushes for each other -- not to kill each other, but for the shear joy of giving the other cat a thorough scare.