As the team headed further into the caves, they made an unexpected discovery: in the deeper recesses, the older, dark-coloured males had become paler, turning a bright orange. Were they losing unnecessary pigment in a similar way to other cave-dwelling animals, such as Mexican blind cavefish?
Shirley doesn’t think so. Cave crocs must maintain contact with the outside world for one simple reason. “They cannot reproduce in the caves,” he says. “It’s a nesting ecology thing: they need big mounds of rotting vegetation to lay their eggs in.”
So while the crocodiles appear to spend the entire dry season in the caves, they emerge during the wet season – at least to breed. Instead of the colour change marking an early stage of subterranean adaptation, Shirley has a more disgusting explanation.
The water these crocodiles swim through is essentially an alkaline slurry formed from bat droppings. “The urea in bat guano makes the water very basic,” he says. “Eventually that will erode away the skin and change its colour.”
From: Weird orange crocodiles found gorging on bats in Gabon’s caves | New Scientist
Photos by Oliver Testa, www.abanda-expedition.org
