Ant Evolves Flashy Way to Beat Desert Heat

A desert ant survives temperatures that can kill other insects and animals with a unique system that is effective, and chic.

Life in the scorching hot Sahara Desert is no problem for an ant that has evolved an effective and stylish heat-repellant system, new research finds.

Saharan silver ants grow flashy body hairs that cause total internal reflection of light, which is a technique also used in manmade fiber optics. New findings about the cool system, published in the journal PLOS ONE, also report a scientific first.

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This is "the first time that total internal reflection is shown to determine the color of an organism," Serge Aron of the Free University of Brussels said in a press release. As the name of the ants suggest, that color is glittery silver.

Aron and his team used a Scanning Electron Microscope to investigate the ant's hairs, watching what happens when incoming light hits them. They also compared normal hairy ants with some that had been shaved with a tiny scalpel blade to measure how light was reflected and how fast the ants heated up under simulated sunlight.

They found that the hairy ants were almost 10 times more reflective than the shaved ones, and were able to stay up to 35 degrees Fahrenheit cooler under simulated sunlight.

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The high-powered microscope revealed that each of the ant's hairs has a corrugated surface and a triangular cross-section. Like a prism, the hairs can then reflect light, such that the light rays entering each hair undergo total internal reflection, bouncing back off the bottom plane of the hair instead of transmitting through it.

The mirror effect gives the ant its bright silver sheen, likely provides some camouflage, aids in ant communications, and reduces heat absorption from sunlight. The latter prevents the ant from overheating.

While many Sahara Desert insects and animals come out at night to avoid daytime temperatures, the Saharan silver ant has no such fears.

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Aron, lead author Quentin Willot and their colleagues wrote: "Workers come out from the nest during the hottest midday period, when temperatures exceed 50°C (122 degrees Fahrenheit), to scavenge corpses of heat-stricken animals."

"By restricting foraging activity to the hottest period of the day," the researchers continued, "the ants minimize the chances of encountering their most frequent predator - a lizard that ceases all activities when the temperature becomes unbearable."

In addition to their silvery hairs, the ants are equipped with legs that are much longer than those of other ants. The long limbs keep their bodies away from the hot surface. They also allow the ants to run very fast, which helps them stay cool by convection.

Saharan silver ant soldiers (larger) with Saharan silver ant workers.

Phrases like “busy bee” and “workhorse” reveal how much insects and animals toil away, but even bees and horses didn't make a newly released list of the top 10 hardest working animals. The

Wildlife Conservation Society

(WCS) compiled the list just before Labor Day to honor the world’s most dedicated workers.


Topping the list is the naked mole rat. Liz Bennett, WCS vice president of species conservation told Discovery News that naked mole rats never take a holiday. “What they lack in good looks, they make up for with their handsome work ethic,” she said. Bennett explained that these subterranean rodents form ant-like colonies and construct intricate underground chambers and tunnels, complete with a queen and workers.


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Although they are relatively small in size, weaverbirds are incredibly industrious. “These diminutive birds construct intricate ‘cities’ from grasses, small twigs and leaf fibers,” Bennett said. “Some of these woven condos can house up to 300 pairs of birds.”


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Each Alpine swift weighs less than a quarter of a pound, but they pack a lot of muscle into their tiny frames. Felix Liechti and colleagues from the

Swiss Ornithological Institute

attached small electronic tags on several of the birds to monitor their movements. The researchers were shocked to find that the birds stayed aloft over West Africa for more than 200 days straight. “Boy are their arms tired, I mean their wings,” joked Bennett. “Who can blame them, flying six months at a clip without ever stopping.”


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Adult American eels make heroic migrations from rivers to the middle of the Atlantic Ocean. It is hardly a pleasure trip.They spawn once and die. As for the newly hatched American eel young, Bennett said, “They must ride the currents on their own across half an ocean to coastal rivers where they will grow up over the next 20 to 30 years.”


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Ants are strong, tenacious workers that contribute to tightly structured communities. Leafcutter ants, however, take the already impressive ant work ethic to a whole new level. Bennett explained that, in addition to the usual ant duties (marching, guarding their turf, taking care of young and more), leafcutter ants “harvest bits of leaves and then grow nutritious fungus from them in underground gardens.” While they are prevalent in Central and South America, leafcutter ants are also found in parts of the southern United States. Those with homes in eastern and south central Texas, for example, probably live over vast leafcutter ant underground “fungus farms.”


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Monarch butterflies are the only insects that make a two-way migration, just as migrating birds do, according to Bennett. “They do it multi-generationally,” she continued, “meaning that their birthright is to keep flying north, or south, as the case may be. Royally impressive.”


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Arctic terns are four-ounce winged wonders. They log an amazing 44,000 miles each year as they fly between their respective winter and summer grounds in Antarctica and Greenland.


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“Chipi chipi” means “smallest” in the


language of Bolivia, where these one-inch-long fish live. Bennett indicated that the fish are world record breakers, completing the longest migration for a fish of their size. “The tiny chipi chipi catfish swims more than 200 miles upstream to the foothills of the Andes in Bolivia,” she said. “No one is exactly sure why, but scientists believe it has something to do with breeding.”


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Humpback whales made the list because of their annual 8,000-mile round trip migration. But as the human population and our presence in oceans grows, so too do the threats to whales. Howard Rosenbaum, director of

WCS’s Ocean Giants Program

explained, “Throughout numerous coastal and offshore areas, important whale habitats and migration routes are increasingly overlapping with industrial development.” Rosenbaum added that hydrocarbon exploration and production, shipping and other forms of coastal and offshore activities pose some of the greatest threats to whales as they travel along their long migration routes.


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No list of hard-working animals could be complete without mentioning busy, industrious beavers. Bennett said, “They are able to change the course of mighty streams with stick-and-mud engineering marvels. Dam(n).” Other animals that could be on this list are herbivores because, as Bennett said, “they can never take a day off. They have to move and find food for much of the day, every single day, unless they are in high latitudes and can hibernate.” As for the laziest animals, some pampered humans and their pets could be contenders. In terms of wildlife, however, snakes probably top the lazy animal list. “After a good meal,” Bennett said, “they can just hang about for even up to a month without moving much until they need to start looking for their next meal.”


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