Find That Flounder

The chameleon has long been considered nature’s expert at hiding from its enemies, but it may have to cede its title to the lowly tropical flounder, according to recent research from UC San Diego.

In its natural environment, the flounder can change its coloring within eight seconds to blend in almost perfectly with an ocean bottom of sand and gravel, according to neurologist Vilayanur Ramachandran.

More remarkable, Ramachandran’s team recently reported in the journal Nature, the flounder makes a valiant attempt to blend in with a pattern of white dots on a black background and even with a checkerboard pattern. Such ability at mimicry is unprecedented in nature, Ramachandran said.

When exposed to the patterns a second or third time, the fish were able to respond in as little as two seconds.

The key to the fish’s ability to camouflage themselves lies in at least six types of skin marking on their surface, including H-shaped blotches, small dark rings and small spots.

Through a mechanism that is unknown, the flounder is able to adjust the darkness of these markings independently to blend into its background.

Ramachandran hopes to understand the neural mechanisms by which the fish control this behavior. He speculates that the flounders may have a separate facet of their visual system to control each of the markings.

The team also observed another interesting behavior of the fish when they sensed predators approaching. In an attempt to distract the predator, they would stir up gravel and dust at one location to make it look like they had buried themselves there. Then they would slip off and, more carefully, bury themselves at another site.