Although these crabs have been becoming popular as pets for the last two years, scientists have finally named them and found their origins. Up until now, these crabs have mostly been mysterious creatures. They have been called vampire crabs and are quite breathtaking to look at.
A purple crab named Geosesarma dinner and a bright orange crab named Geosesarma Hagen originated in two separate river valleys on the Indonesian island of Java. These crabs have unusually bright colorings. Thought to be an evolutionary result of their amphibious nature, meaning they spend lots of time on the sand, as well as in the water. They are freshwater creatures when they are in the water, however.
These crabs caught the attention of German aquarist Christian Lukhaup when they started being sold around the world as pets. He had never seen anything quite like them. He quickly realized they didn’t even have a name and he set out to figure out where they were coming from.
He scouted out collectors in the aquarium trade to give him clues. “There were a lot of false rumors because people don’t want other collectors to go there,” he said.
He was finally able to track them down in Central Java, where he and his colleague documented their features, named them, and published their findings in the Raffles Bulletin of Zoology.
“Dealers working in Southeast Asia and other parts of the world know what their clients are looking for in terms of colors,” said study co-author Christoph Schubart of Germany’s Regensburg University’s Institute of Zoology.
“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 scientists suspect there are many more vampire crab species yet to be discovered on the islands of Indonesia. Since freshwater crabs never venture to the ocean and tend to stay put, each of the islands likely has its own unique vampire crab species, Schubart said.
While their main attraction is their wild color schemes, vampire crabs measure less than an inch wide, making them an ideal size for small fish tanks.