All of you are used to seeing flies putter around our house. We particularly see them in the summer time and when we eat outside during picnics and such. But how many times have we seen flies breathe underwater?
In Mono Lake, which is in California, there is a very bizarre hairy alkali fly. Scientists have discovered that these “diving” flies have demonstrated the ability to survive the very alkaline waters of this lake, as they creep right into it to lay their eggs and even feed. The trick is that their body helps to generate air bubbles around them that become an external lung for them.
These studies were performed by Floris van Breugel, who is postdoctoral candidate from the University of Washington. It was The National Geographic Society that funded van Breugel to examine these flies of Mono Lake. It is the very same fly species that the famous Mark Twain described in his book, Roughing It, around 150 years ago—“because they’re really just that entertaining to watch,” noted van Breugel.
The fly population at Mono Lake is pretty impressive. Their density is so vast that an areas equal to the size of a postcard could contain over 2,000 of these flies. van Breugel has estimated that at the peak of the summer season, there could be as many as 100 million of these alkali flies flying around the lake.
But when you take a close look, that is when things get very interesting, “You can start to see them actually crawling underwater in little air bubbles,” he claims.
Solving a Mystery
van Breugel and his research team had a goal of understanding the way that the alkali flies of Mono Lake have been able to crawl into the lake’s water. And this water is about three times saltier and has extremely more alkaline than the Earth’s oceans, and they do not even get wet. The only other known animal that inhabit the lake during the entire year are some photosynthetic algae and some tiny shrimp. This research was reported in Proceedings of the National Academy of Sciences.
The researchers constructed a sensor that was capable of measuring small forces and then they dunked these alkali flies into various solutions. They were shocked to discover that the more concentrated the lake water the easier it was for the flies to drown. But when the solutions contained less salt and other mineral content the opposite was true. The main culprit was discovered to be sodium carbonate. Not only is this mineral a great cleaning solution, but it was also used in history to preprocess mummies during ancient times in Egypt.
The sodium carbonate in the water makes it more difficult for the alkali flies to remain dry, since the water flows more easily into spaces between the little hairs on their body. Through evolution the bodies of these hairy alkali flies has produced more hair over time—in fact, they has grown about 36% more hair than other flies. And these hairs on the bodies of the flies are coated with a special wax that helps them stay dry. It is same as when you wax your car to make it more weather-repellent.
“Because of these tiny adaptations, the alkali flies are able to occupy a niche that very few other animals can tolerate,” van Breugel has noted.