Africa: Bizarre Orange Crocodile Mutating Into New Species After Thousands of Years Stuck in Pitch-Black Caves

The cave-dwelling 'Osteolaemus tetraspis.' Abanda Expedition

A cave-dwelling population of dwarf crocodile in Gabon is already notable for being orange. New research indicates that it has so heavily adapted to its extreme environment that it's splitting off to become its own species. After thousands of years in the soggy darkness of Gabon's Abanda caves, the crocs' DNA is evolving into something new, according to the Guardian. They're the only crocodiles in the world known to be undergoing such changes.

"We could say that we have a mutating species," archaeologist Richard Oslisly, who first discovered the crocodile population in 2008, told the Guardian. "Its diet is different and it is a species that has adapted to the underground world."

The dwarf crocodiles are officially known as Osteolaemus tetraspis, according to the website of exploration group Abanda Expedition. Oslisly told the Guardian he was initially exploring Gabon's Abanda caves in 2008 for archaeological remnants like rock art, only to be greeted by a "great room" filled with ancient reptiles.

Yet he didn't discover that some of the crocs were orange until two years later, when he returned to capture a specimen and brought it outside for the first time. In the light, it was a lot more obvious that the croc wasn't the color researchers would expect it to be. Oslisly and his colleagues have found roughly 30 or 40 crocs to date; 10 are orange. There might be as many as 200 scattered throughout the caves, according to National Geographic.

By sequencing the DNA of different croc populations, the researchers discovered that the Abanda cave crocs were inheriting their own unique haplotypes, the term for a group of genes that one parent passes to its offspring, according to National Geographic. In other words, they are becoming their own species.

The crocs' march toward classification as a distinct genetic group has to do with the fact they spend so much time isolated in complete darkness. While they're still young and not yet full-sized, they appear able to move in and out of the caves through different small crevices in the rock, according to the Abanda Expedition website. But when they get too big, they become stuck—remaining inside the pitch-black caves for the rest of their lives.

"They are somehow in their own prison," Oslisly told the Guardian. "They eat bats that live in these caves by the tens of thousands, and also crickets that swarm the walls."

Adapting to those extreme conditions is changing their DNA, and those distinct genetics are further set apart by the fact that the crocodiles aren't mixing with external populations. As a result, they're evolving in a manner sufficiently different from other crocodiles as to warrant their own category.

(Don't worry, this croc is fine.) Abanda Expedition

Their unique lifestyle is probably the reason some of the crocs are orange. The color change is a characteristic of the older specimens, possibly because once they can no longer leave the cave, they spend all their time sitting in a mix of water and bat poop, which has a bleaching effect on the skin, according to the Guardian.

"It looks like liquid mud," cave scientist Olivier Testa told National Geographic, "but it's not mud."