Nevada is officially known as the "Silver State" because of the importance of silver to its history and economy. It is also known as the "Battle Born State", because it achieved statehood during the Civil War (the words "Battle Born" also appear on the state flag); as the "Sagebrush State", for the native plant of the same name; and as the "Sage-hen State".
The Devils Hole pupfish, Cyprinodon diabolis, is a species of fish native to Devils Hole, a geothermal (92 °F or 33 °C), aquifer-fed pool within a limestonecavern in the Amargosa Desert of Nevada east of Death Valley. It is the smallest desert pupfish species, averaging 19 millimetres (0.75 in) in length. They lack pelvic fins and have large heads and long anal fins. Breeding males are solid deep blue and have a black band on the caudal fin. Devils Hole pupfish have been the subject of considerable attention and litigation, due to their ancient origins, unusual habitat, and precarious existence. A 22-thousand-year-old species, these pupfish depend on a shallowly submerged limestone shelf of only 2 metres (6.6 ft) by 4 metres (13 ft) in area for spawning as well as for much of their diet (primarily diatoms). Natural threats from flash floods to earthquakes have been known to disrupt this fragile ecosystem, but the major threat has been groundwater depletion due to agricultural irrigation.