The lungfish, also known as salamanderfish, is a type of freshwater fish best known for its ability to live on land, without water, for months on end, and sometimes even years. As its name suggest, the lungfish have a highly evolved respiratory system that can take oxygen straight from the air, just like land animals do. In fact, some species of lungfish are so used to breathing air that they slowly lose the function of their gills as the fish approach adulthood. While they still live in water, they need to regularly come up to the surface for air. These fish can even drown if they are held underwater for a long time.

A lung fish in its cocoon lying outside its burrow. Photo credit: Scrubhiker (USCdyer)/Flickr