Researchers have finally traced the newly described freshwater crabs, Geosesarma dennerle and Geosesarma hagen, back to their roots in southeast Asia, according to National Geographic.

"These crabs are kind of special because they've been around in the pet trade for 10 years, but no one knew where they come from," study co-author and professional aquarist Christian Lukhaup of Waiblingen, Germany told National Geographic.

"Dealers working in southeast Asia and other parts of the world know what their clients are looking for in terms of colors," study co-author Christoph Schubart of Germany's Regensburg University's Institute of Zoology told National Geographic. "They start collecting in areas where scientists may not have made any expeditions so far, and suddenly the market is formed with some animals that no one has ever given a name."

The study appeared in the January issue of Raffles Bulletin of Zoology.

Lukhaup was born in Transylvania, so he was able to use his contacts to search for vampire crab collectors. "There were a lot of false rumors because people don't want other collectors to go there," he told National Geographic.

There might be more vampire crab species still unknown to scientists as these freshwater crabs don't use the ocean as part of their life cycles. Indonesia's islands could each have their own species of vampire crab.

The eye-catching colors of the vampire crabs could be a result of their amphibious lifestyle, Schubart said. On land, versus in water, "visual communication becomes much more important," he told National Geographic. "There's much more emphasis on color and visual cues rather than chemical cues, as used in the water."

Because of their vibrant colors, the vampire crab is susceptible to human predation. "For the local collectors, it's their living," Schubart told National Geographic. "They just catch what they can get and export it."

Commercialized breeding could potentially prevent wild populations from dwindling, but despite efforts by private breeders of vampire crabs, most of the exports are still coming from Indonesia.