Let's come up with an amphibian race!

Regarding crocodiles, let's say there's a 20% chance they'll attack. This will work if the number of crocodiles is equal to or greater than the number of units they are attacking, but not if it's less. Maybe that would work... Also, what will be the name of this unit? If it's "crocodile," it doesn't sound very good; it's better to come up with something else.