Living at the margins

As habitats go, Devils Hole is not very hospitable.

The water in the cavern 90 miles west of Las Vegas is thermally heated to a constant 93 degrees and carries barely enough dissolved oxygen to support life.

At the surface, Devils Hole is only about 8 feet wide and 60 feet long. The steep cavern walls shield the water from the sun for much of the year, which limits the growth of algae the native pupfish feed on and hide in to avoid predators.

Though the fish rarely descend below 100 feet, the water-filled cave goes down at least 430 feet into the ground.

“It’s not really known how deep the water system goes,” said Jeffrey Goldstein, fisheries biologist and chief dive officer for Death Valley National Park.