Space alligators

An "Alien Species" of Space Alligators lives on The Moon. They dwell within the Moon's many valleys, require oxygen masks to survive and, like alligators on Earth, are very territorial. There may be gator farms on the moon, since oxygen helmets do not grow naturally. Because of the helmets, they may be normal alligators with space helmets on. They can't actually do any harm with their jaws because of the helmet.