California’s aboriginal Yokut people, who used some of these caverns for ceremonies, may have been the first to glimpse the Sierra troglobites; they left pictographs of scorpions and spiders at entrances. Starting in the 1970s, scientists spotted a few, including a blind harvestman (daddy longlegs) with gigantic jaws for seeking out prey in the dark. In 2002, after years of growing awareness of species diversity in the region, the parks commissioned a survey led by Jean Krejca, an Austin biologist, and the parks’ cave specialist, geologist Joel Despain.
One summer day last year, Krejca and Despain threaded their way down a remote, brush-choked canyon through poison oak and heaps of giant boulders toward Sequoia’s Hurricane Crawl Cave. Tucked into a cliff was a black, funnel-shaped hole, fringed with thimbleberry shrub. On an otherwise still morning, the shrub’s broad leaves were dancing: A breeze from the hole signaled it as an entry to another world, one with its own weather system. Krejca and Despain drew a deep breath, thrust their arms forward, and wriggled through 60 feet (18 meters) of twisting tube that pressed like a tight suit. They emerged in a tall, chill, shoulder-wide corridor floored with rubble.
Cut off from the fruits of photosynthesis, most caves are places of hunger. Yet, most depend indirectly on the sun. In some caves, like Hurricane Crawl, rootlets from trees far above dangle through cracks in ceilings, providing bug food. Leaves and twigs wash in on spring floods from nearby connected creeks. Rodents penetrate surprisingly far, bringing seeds and nesting material. Bats also come and go, leaving behind guano, and their dead. Occasional “accidentals”—big animals like raccoons or snakes—wander in but don’t wander out, providing banquets that may stoke the food chain for centuries (in one Sequoia cave, debris and bones are piled a hundred feet deep in a pit trap). Hurricane Crawl is named for 30-mile-an-hour (48-kilometer-an-hour) gusts that roar in through blowholes, driven by temperature fluctuations outside; these gusts may bear organic dust.
At least a dozen known caves from Romania to Wyoming have no ecological connection to the surface; they run on purely geologic substances such as sulfur compounds, methane, iron, and hydrogen eaten by specialized microbes, which in turn feed higher organisms. Israel’s Ayalon Cave, uncovered accidentally in May 2006 by excavation in a rock quarry near Tel Aviv, was probably sealed for millions of years. Warm groundwater laced with sulfur appears to be feeding microbes and, ultimately, at least ten previously unknown crustaceans and other creatures. The fact that Ayalon was found in an area inhabited by people since ancient times suggests that the world holds many more such caves.