The Devils Hole pupfish is one of the world's rarest fishes, spending most of its life in the top few meters of very warm waters of a cavern located in the middle of the Mojave Desert. Devils Hole, a geologic pool, is the only naturally occurring habitat for the endangered Devils Hole pupfish. This fish's habitat is one of the smallest natural ranges known for any vertebrate. Devils Hole is an
extreme environment, with water temperatures and dissolved oxygen concentrations near the lethal limits for most fish species.
Which of the following statements best explains why the Devils Hole pupfish are able to live in this environment?