National Geographic : 2010 Aug
• from speleothems will shed light on today's rapid warming and the associated rise of sea level. " e better we understand how the natural climate sys- tem works," Swart says, "the better we can under- stand the nature and degree of our own impact." ' , I tie o our safety reel to the line at the entrance of South Passage and follow him inside. In the play of our lights, the natural geometry of the corridor is breathtak- ing. Above soars a vaulted, triangular ceiling; below, a oor of impenetrable darkness. ere is an eerie quality of intention---the vaulted cor- ridor seems more designed than randomly oc- curring---and I'm reminded simultaneously of the outer walls of Mycenae and the gallery in Khufu's Great Pyramid. Covering my light with my palm, I hover and watch Kakuk's single lamp move steadily forward as the walls' steep angles come into view. I had expected a measure of anxiety in such an alien environment, but for all its unearthly surrealism, this motionless, lightless place is profoundly calming. For a mo- ment I relax completely, releasing an attenuated breath and swinging my light upward through the swarm of ascending bubbles. Two hundred lateral feet into South Passage, Kakuk collects a water sample for Macalady in a plastic tube. He points out a sh with a shim- mering, translucent tail that ickers like a candle ame---a Lucifuga, about ve inches long. Like most life-forms in these lightless depths, the sh is blind. en Kakuk directs my attention to a Barbouria shrimp, a reddish, two-inch crustacean with long, bowed antennae for sensing prey in the darkness. Minutes later, he pauses and shines his headlamp on his ngertip---his signal for the presence of the tiniest creatures. It's an ostracod, a crustacean no bigger than a sesame seed, its brilliant pink interior sheathed in a transparent, clamlike shell. High on its round body, a pair of antennae utter like fairy wings, propelling the animal through the water. Kakuk is known for his ability to spot things most other divers---including trained scien- tists---never see. During his 21-year career div- ing in blue holes, he has discovered more than a dozen new animal species, four of which expedi- tion scientist Tom Ili e, himself an expert cave explorer and a professor of marine biology at Texas A&M University, has named a er Kakuk. In recent decades Ili e and other scientists have discovered an astonishing abundance of previ- ously unknown organisms in these and other ooded caves around the world: more than 300 new species, 75 new genera, nine new families, three new orders, and a new class, Remipedia, rst documented in 1981 in the Bahamas. Most cave-adapted species are crustaceans, and many, like the remipedes, are "living fossils"---live species closely resembling those preserved in the fossil record. Ili e says that the greatest percent- age of saltwater cave species come from blue holes in the Bahamas, including 18 of the 24 known species of remipedes. Remipedes emerged 300 million years ago and give scientists a rare look at life in the Carboniferous period---tens of millions of years before dinosaurs appeared. With slen- der, segmented bodies less than two inches long and usually colorless and blind, remipedes are, nonetheless, at the top of the food chain in their habitats, using hollow, venom-injecting fangs to kill shrimp and other crustaceans. into South Passage, the only sound is the rhythmic hiss of our regulators and the rumble of our exhaled breaths. Kakuk oc- casionally traces a broad circle with his light on the passage wall, signaling the question, "OK?" I return the signal as an a rmative response. I've known Kakuk less than two months, but my life depends on his judgment, and his, to some degree, on mine. In cave diving, redundancy is critical. If one of my lights goes out, I have three in reserve. Our gas supplies---in this case oxygen-enriched nitrox, a combination of oxygen and nitrogen--- are backed up with two independent tanks and regulator systems. As long as we follow the rule of thirds (one-third of your total gas going in, one-third coming out, and one-third in reserve n Society Grant This project was funded in part by your National Geographic Society membership.