“Orange crocodile” sounds like a new cocktail with a bite (vodka, orange juice and a dahs of Tabasco?), but it’s an accurate description of the small crocodiles found in the Abanda cave system of Gabon, a nation on the Atlantic coast of Central Africa. While their bright orange hue is attractive in a lizard-y sense, its cause was a mystery until recently. A new study found that, while their main diet is bats, it’s not from something they ate.
The orange crocodiles were first discovered in 2010 by a group of scientists on an expedition to study the 50,000 bats and millions of insects in the Abanda caves. They managed to obtain some DNA samples and later determined that this was a species of dwarf crocodile (Osteolaemus tetraspis) with slight genetic differences from those that lived above ground – in addition to their orange color, broader bodies and acute blindness. From that they discerned that these orange crocs had been isolated in the caves for a few thousand years.
How did these orange crocodiles manage to survive? Expedition crocodile expert Matthew Shirley from the Rare Species Conservatory Foundation had the answer.
You walk in and there are just bats and crickets everywhere. The crocodiles are pretty good hunters anyway, but even if they didn’t have to pull bats off the walls, there are individuals falling to the floor all the time.
However, he didn’t have an explanation for their unique coloration. A new expedition was launched in 2015 and this one located more orange crocodiles, bringing the total to at least 50. They found one old croc that was 1.7 meters (5.6 feet) long, larger than the average of 1 meter (3.3 feet). The most interesting discovery was that the crocodiles aren’t trapped in the caves but leave annually for an important reason, says Shirley.
They cannot reproduce in the caves. It’s a nesting ecology thing: they need big mounds of rotting vegetation to lay their eggs in.
By following the crocs to their mounds of rotting vegetation, Shirley also discovered the cause of their orange color and it’s grosser than the mounds of rotting vegetation. The water they swim in is loaded with bat droppings, making it heavily alkaline.
The urea in bat guano makes the water very basic. Eventually that will erode away the skin and change its color.
Now that everyone knows about the existence of these orange crocodiles, will we be seeing orange leather belts and wallets until they’re extinct? Fortunately not. Shirley says the dwarf crocodiles slip through narrow passages far too small for humans. Then there’s the guano-loaded water and mounds of rotting vegetation to contend with.
Besides, everyone would know you’re a croc poacher when you suddenly start resembling an Oompa Loompa.