Scientists solve the mystery of America's scuba-diving fly

WASHINGTON (Reuters) - A small fly that thrives at an inhospitable California lake east of Yosemite National Park long has perplexed observers who watch as it crawls into the severely salty and alkaline water, snacks on some algae or lays some eggs, then emerges dry as a desert.

Research published on Monday finally explains the secrets of this scuba-diving insect.

These quarter-inch-long alkali flies possess specialized traits that let them conquer Mono Lake, scientists found. They are covered in a large quantity of fine hairs coated with special waxes that let them encapsulate themselves in a body-hugging bubble that protects them from water that would doom an ordinary insect.

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The El Capitan monolith in the Yosemite National Park in California on June 4, 2015. It is one of America's most popular natural wonders. But even Yosemite National Park cannot escape the drought ravaging California, now in its fourth year and fueling growing concern. At first glance the spectacular beauty of the park with its soaring cliffs and picture-postcard valley floor remains unblemished, still enchanting the millions of tourists who flock the landmark every year. But on closer inspection, the drought's effects are clearly visible. AFP PHOTO/MARK RALSTON (Photo credit should read MARK RALSTON/AFP/Getty Images)
YOSEMITE NATIONAL PARK, CA - MAY 20: A view of Half Dome at sunrise on May 20, 2015 in Yosemite National Park, California. (Photo by Brendon Thorne/Getty Images)
A hiker sits on rocks as water flows down Yosemite Falls, the highest waterfall in North America in the Sierra Nevada mountain range at Yosemite National Park on March 25, 2015 in California, where the snowpack in the mountain range hit an unprecedented low this week, falling below historic lows of 2014 and 1977 for the state's driest winter in sixty-five years of record keeping. It is the melt from the Sierra Nevada and Cascade mountain range snowpacks from which California gets its water, but snowpack measurements due to be reported next week are expected to be the lowest on record leaving the parched 'Golden State' in its fourth year of drought. AFP PHOTO / FREDERIC J. BROWN (Photo credit should read FREDERIC J. BROWN/AFP/Getty Images)
Mirror Pool in Yosemite at Sunset looking at Half Dome. (Mauricio Fernandez via Getty Images)
UNITED STATES - SEPTEMBER 24: Yosemite National Park spans eastern portions of Tuolumne, Mariposa and Madera counties in California (Photo by Carol M. Highsmith/Buyenlarge/Getty Images)
UNITED STATES - SEPTEMBER 23: Yosemite National Park spans eastern portions of Tuolumne, Mariposa and Madera counties in California (Photo by Carol M. Highsmith/Buyenlarge/Getty Images)
YOSEMITE NTL PARK, CA - AUGUST 28: Two deer graze in a Yosemite Valley field on August 28, 2013 in Yosemite National Park, California. As the Rim Fire continues to burn on the western edge of Yosemite National Park, the valley floor of the park remains open. The Rim Fire has charred more than 190,000 acres of forest and is currently 30 percent contained. (Photo by Justin Sullivan/Getty Images)
YOSEMITE, CA SEP. 13, 2013. Burned trees in the foreground and the mountain top beyond in the Stanislaus National Forestnear Tuolumne, on Sep. 13, 2013. Soil Scientist Todd J. Ellsworth of US Forest Service and Manager of Forest BAER(Burned Area Emergency Response) with his team collecting data in the burned area of the Rim fire near Yosemite. US Forest Service team surveying the area to gauge environmental damage from the fire. (Photo by Lawrence K. Ho/Los Angeles Times via Getty Images)
A photographer at Olmsted Point casts her shadow against the boulders just before sunset in the high country off Tioga Road in Yosemite National Park May 21, 2013 (Photo by Mark Boster/Los Angeles Times via Getty Images)
Park Ranger Bob Roney walks across the entrance of the Wawona Tunnel in Yosemite National Park, framing the famous Tunnel View May 20, 2013. Roney has been a ranger at Yosemite for for almost 46-years and said his first visit to the park stole his heart and ever since then, his whole life has been centered on the valley (Photo by Mark Boster/Los Angeles Times via Getty Images)
The Vernal Fall, Yosemite Park. (Photo by: Godong/UIG via Getty Images)
Taken just after sunrise the Swinging Bridge over the Merced River. Fresh snow from the night before adds to the photo. (David Toussaint via Getty Images)
Merced River in Yosemite Valley, California (Photo by: Education Images/UIG via Getty Images)
A Winter sunset at The Gates of the Valley, Yosemite National Park, in the California Sierra... The water of the Merced River reflected the alpenglow striking El Capitan high above. It was cold enough that the tufts of snow were covered in perfectly formed spiky ice crystals. (Joseph Ganster via Getty Images)
A mule deer weathers Sunday's snowstorm in Yosemite Valley, California on December 23, 2012. (Elias Funez/Modesto Bee/MCT via Getty Images)
UNITED STATES - OCTOBER 01: Yosemite National Park spans eastern portions of Tuolumne, Mariposa and Madera counties in California (Photo by Carol M. Highsmith/Buyenlarge/Getty Images)
A large coyote stares straight into the camera in Yosemite National Park. Snow and pine trees out of focus in the background. It was winter and the coyote had a very thick coat which makes him look even bigger, and maybe a little wolf like. Yosemite is in the Sierra Nevada Mountains, in California. The coyote has lots of red in his coat, which comes out very nicely if the red saturation is pushed up, there is nothing else red in the photo. The coyote was out earning a living even in the stormy weather. (Jeffrey McLean via Getty Images)
YOSEMITE NATIONAL PARK, CA - JANUARY 3 2012- A couple skates across the frozen surface of Tenaya Lake in Yosemite National Park January 3 2012, with Yosemite high country in the backdrop nearly devoid of snow. The Tioga Road is open through the park, a and the lack of snow is creating new and missed opportunities for recreation in the Sierra Nevada Range. (Photo by Brian van der Brug/Los Angeles Times via Getty Images)
USA, California, Yosemite National Park, Cloudy sunset at yosemite (Photo by: JTB Photo/UIG via Getty Images)
USA, California, View of half dome at Yosemite National Park (Photo by: JTB Photo/UIG via Getty Images)
USA, California, View of half dome at Yosemite National Park (Photo by: JTB Photo/UIG via Getty Images)
UNITED STATES - AUGUST 02: Spectacular Yosemite Falls, Yosemite National Park, California (Photo by Carol M. Highsmith/Buyenlarge/Getty Images)
Yosemite National Park awakens from a long Winter nap and comes to life during Spring and Summer with wildflowers, waterfalls and tourists May 11, 2009. Hikers make their way up the Mist Trail leading to the top of Vernal Falls. (Photo by Mark Boster/Los Angeles Times via Getty Images)
UNSPECIFIED - OCTOBER 28: USA, California, Yosemite National Park, Golden-mantled Ground Squirrel (Spermophilus lateralis) (Photo by DEA / G.SIOEN/De Agostini/Getty Images)
Ryan, right, and Emily Joki, of Los Angeles, take in a partially obscured view of Yosemite Valley, with El Capitan at left and Bridalveil Falls at right from Tunnel View turnout, the spectacular view at the west end of the valley and some say one of the greatest scenic 'views' in the country. (Photo by Mark Crosse/Fresno Bee/MCT via Getty Images)
WINTER, YOSEMITE VALLEY: The orange hues of the sunset color the skies over Half Dome on a snowy ebvening in late winter March 22, 2010 (Photo by Mark Boster/Los Angeles Times via Getty Images)
Valley View in Yosemite National Park, the Merced River flowing toward El Capital and Half Dome, California, United States. (Photo by: MyLoupe/Universal Images Group via Getty Images)
Black tail deer doe with fawn, Yosemite National Park, California, United States. (Photo by: MyLoupe/UIG via Getty Images)
371021 03: A hazy summer day in Yosemite Valley may be the result of humidity, exhaust from vehicles in the valley, or polluted air blowing in from far away San Francisco Bay and the San Juaquin Valley, June 16,2000 in Yosemite National Park, California. The National Park Service hopes to reduce the number of cars within Yosemite Valley. The giant rock formations of Half Dome (center) and El Capitan (left) are visible through the haze. (Photo by David McNew /Newsmakers)
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"The flies have found a great gig -- all the food they want with few predators. They just had to solve this one tricky problem," said California Institute of Technology biologist Michael Dickinson, co-author of the study in the Proceedings of the National Academy of Sciences.

All insects are hairy and water repellant to some degree. These alkali flies, whose scientific name is Ephydra hians, have magnified both traits to overcome the extreme conditions of Mono Lake, considered among the "wettest" water on Earth with a slippery, nearly oily feel. The water tends to attach to any surface due to exorbitant amounts of sodium carbonate, a chemical used in laundry detergent.

"The study provides a clear example of evolution in action," added co-author Floris van Breugel, a former Caltech postdoctoral scholar now at the University of Washington.

"The flies have evolved to crawl under water so they can feed on the abundant food, alga, that grows there. The lake has no fish because the fish cannot live in the harsh chemicals of the lake. Thus, the flies have no major predators in the lake. Fish are why most insects would be crazy to crawl under water."

American author Mark Twain was among those who remarked about these flies at the 12-mile-wide (19-km) Mono Lake, which is three times saltier than the Pacific Ocean. They also live at Oregon's Lake Abert and Utah's Great Salt Lake, also salty and alkaline.

The flies use sharp foot claws to crawl into the water from rocky outcroppings. Their hairy bodies trap a layer of air that envelops them in a protective bubble, except for the eyes to permit good underwater vision. After eating or laying eggs, they let go and float to the surface, where the bubble pops, leaving them safe and dry.

(Reporting by Will DunhamEditing by Sandra Maler)

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