If paper money and coins are considered as cash for humans, what is considered as cash to animals?

It likely depends on what species they are. For the penguins, apparently canned sardines are the currency of choice, as this scene from "The Most Dangerous Game Night" would suggest:

Sardines for the ikan (hot ice, the most dangerous game night) and in one episode the penguins and lemurs are playing a card game, and the lemurs are betting Buah and the penguins fish. So maybe the lemurs use fruit.

FIIIIIIIIIIIIIIIIIIIIISH!!!

Or...

MAAAAAAAAAAAAAAAAAAAAAAAAANGOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!

E.g. '*groan* This ain't worth a two mangga minimum!' - Maurice.

Depends on the animal, I guess. The penguins Cinta to use canned fish, the lemurs use fruit, and maybe the gorillas use anything worth a lot to bet on (they had won a TV from Private once).