Although it is difficult to believe, there are fish living in the desert. Several important expeditions have gone to the Sahara to uncover the mystery of these fish which are sometimes found scores of meters down.

The most famous is the lungfish which lives in the larger African rivers. When these overflow their waters can spread out to desert regions to form small lakes or ponds. When the lake dries up the lungfish buries itself in wet mud where it can live for months on end, especially if it goes deep enough to find an underground layer of water.

Lungfish are among the most ancient bony fishes and are very like those which lived 200 million years ago, at the beginning of the Mesozoic Era.