In 2010, a group of scientists went on an expedition into the Abanda caves in the rainforest of Gabon. Among the many creatures they found there—bats, snakes, moths, spiders, crickets, scorpions and other insects and arachnids—there was a surprise. While making his way through a narrow passage, one of the scientists caught the reflection of two big eyes in the light of his headlamp. He was face-to-face with a crocodile. As he stood frozen wondering what he should do, the croc disappeared down the tunnel.
Crocs in caves are rare, but not unheard of. The reptiles are known to shelter in caves and caverns in Madagascar and Mauritania, but when the scientists tracked down and captured a few of the Abanda crocs, they found they were strange in ways besides their choice of home.
They were orange.
Some of the animals were clearly trapped in their underground home, and found in parts of cave system that were only accessible through a 7-meter-deep pit. While the rest of the crocs had more freedom to move around, the genetic and physical differences (broader heads, poorer eyesight and that strange orange skin) between them and crocodiles living on the surface suggested that the cave population had been isolated for a few thousand years.
The researchers think that the caves may have been more accessible in the past and a few crocs found shelter there, but over time the entrances they used filled in with sediment that kept them from coming and going on their own and cut them off from the outside world.
The group of cave crocs, which was 20 strong when the researchers made their expedition, live in complete darkness and are almost blind. Their diet consists of their underground neighbors—mostly bats, insects and a good amount of algae. Their unique color could be caused by any number of things: a physiological change linked to a life in darkness, their diet, or even a chemical reaction to algae or something else in the water or on the caves’ rock surfaces.
There are no hard answers yet, as the research is still ongoing, but you can get a peek at the scientists in action. A film crew accompanied the scientists on expedition and released a documentary about it last year for French television. You can watch a trailer here.