This desert rodent can live its entire life without ever taking a drink

Kangaroo rats survive in North American deserts on the water contained in dry seeds alone, produced internally when their bodies metabolize food. Kidneys far more efficient than a human's concentrate urine to a fraction of the water loss, and they shelter in cool burrows by day to avoid sweating it away. Physiologist Knut Schmidt-Nielsen's studies made them a textbook case of extreme desert adaptation.

— Knut Schmidt-Nielsen, Desert Animals: Physiological Problems of Heat and Water — 1964