According to foreign media reports, it is difficult to determine whether an animal is extinct or extremely good at hiding, especially for animals that are already elusive like frogs. But now, researchers have shown a new way to track lost species by looking for their loose DNA in the environment. < / P > < p > however cunning a creature may be, it cannot prevent DNA from being released into the environment through skin, fur, hair, scales, feathers, urine, feces, and other wastes. This environmental DNA (Edna) can be tracked and analyzed, and it can let people know which organisms live in a certain area – even without directly seeing or capturing them. < / P > < p > in recent years, Edna has been used to track fish migration, monitor great white sharks, invasive clams and starfish, study ancient human species living in some caves, and even discover that the Loch Ness monster may be just a giant eel. < / P > < p > now researchers at Cornell University are using the technique to track frog species that have been forgotten by science for decades. The team began searching for 30 amphibians in six areas of the Atlantic coast forest and the Brazilian selado prairie, where they were previously known to live. < / P > < p > first, researchers enter the Brazilian jungle, take samples from streams and ponds, pump it into a filter to capture DNA, and then seal the DNA for research. Back in the lab, the team extracted the DNA and sequenced it, then filtered the DNA from other animals until only frog DNA was left. < / P > < p > in the end, the team found Edna evidence for seven particularly interesting frog species. One of the top stars is megaelosia bocainensis, which has so far been found only in a single specimen collected in 1968. < / P > < p > the team also found evidence for four species of frogs that were once common in the area but are now rare, and two species found elsewhere – they are thought to have disappeared completely from these areas. < / P > < p > “a small amount of DNA in the environment can’t tell us how many individuals there are or whether they are healthy, but it can tell us that the species still exists,” said Kelly, lead author of the study “This is another kind of survey data, and for species that are declining or partially disappearing, it doesn’t just mean they’re still there, but it’s possible to study them in more detail now,” Zamudio said More Samsung devices can now run Android applications on PC through your phone