GOOD camouflage may require a speedy makeover, as this frogfish living on a bleached coral shows.
Warty frogfish are sedentary seafloor dwellers that can change colour over a few weeks. By seamlessly blending in with their surroundings, they keep themselves invisible to prey.
Since the warm waters off the Maldives abound in vibrantly coloured corals, the frogfish there typically sport matching orange or pinkish hues, says Gabriel Grimsditch of the International Union for Conservation of Nature Maldives in Malé. But rising ocean temperatures have led to widespread coral bleaching (Coral Reefs, doi.org/brvr).
Diving in North Ari atoll in May, Grimsditch and his team photographed an unusual white frogfish resting amid the bleached corals. Its dark protruding warts mimicked bits of brownish algae growing on dead parts of the coral skeletons. “It was fascinating, because we had never seen a frogfish that had changed colour to become white because of a bleaching event,” says Grimsditch.
Frogfish rarely change location, so this individual had probably been in that spot for a while. It probably turned white as the corals bleached in late April or early May, when ocean temperatures were unusually high.
Might it change colour again if the coral becomes overgrown with brown algae? “I would think it would – that would be my guess,” says Grimsditch.
This article appeared in print under the headline “Frogfish turns ghostly white to match a bleached coral”