Most are nocturnal and avoid heat and intense sunlight. Those that remain active during the day retreat to rocky burrows in the lava or other shady locations during the hottest hours. Some creatures have more sophisticated mechanisms for reducing body temperature. Jackrabbits, for example, radiate heat from their ears when air temperature climbs higher than body temperature. Blood flow through the large surface area of the ears dissipates body heat.
Marmots take more extreme measures.
When conditions become too hot and dry, they go into a state of deep stupor called estivation, during which their metabolism and other body functions drop for weeks at a time. Animals living on the lava flows have essentially no access to water and must get their moisture directly from their food. This is true regardless of whether they are consuming plants, insects, or larger animals. Two animals at Craters of the Moon have developed distinct subspecies which are darker in color than their relatives elsewhere, the pika and pocket mouse. This adaptation protects them from predators, since it makes them more difficult to see against the dark surface of the lava.