What are characteristics that allow frogs to live on land?

Frog's are alot like wizards, some are of pure blood, some mudbloods and some are muggle born. It is only pure bloods that can truly live on land, as mudbloods die after a day out of water, and a muggle born frog cannot even get out of water. This is were the saying 'like a fish out of water' comes from.