Speckles, Style And Blending In

Many can also respond rapidly to their environment, shifting from one shade to another as they move place to place. Flounders are masters of such speedy camouflage and can change from being pale, speckled entities to disappearing into the dark in just a matter of seconds.

They are able to change colour due to the presence of pigment-containing cells called chromatophores. One type of chromatophore contains a very dark brown pigment called melanin, the same pigment that gives us our tans and freckles, which can be released to make the animal appear much darker.

On light backgrounds the pigment is concentrated into a tiny spec in the centre of the cell, so most of it appears white. On darker backgrounds, this pigment is dispersed throughout the cell to create an even tone. It's much like when you spill an otherwise unnoticeable spec of bolognese sauce on your white shirt, try to rub it out with a napkin and the nearest water source and blend it into a prominent, glaringly obvious orange stain - with the exception that the ‘stain' in a chromatophore is much darker, reversible and entirely intended.

Fish don't only go from black to white and back again either. They are also capable of creating a speckled spectrum to suit their substrate and if they're lucky enough to join a few scientists in a game of underwater chess, they could even blend in with the board!

Reference

Ramachandran, V. S., Tyler, C. W., Gregory, R. L., Rogers-Ramachandran, D., Duensing, S., Pillsbury, C., & Ramachandran, C. Rapid adaptive camouflage in tropical flounders. Nature 379 815-818 (1996).

Images and videos

1) Flounder camouflage at its best. Credit: Moondigger via Wikimedia Commons

2) An intermediate flounder styling out the substrate. Credit: Nick Hobgood via Wikimedia Commons

3) Chromatophores in action - a close up of melanin-containing cells in a tilapia fish. Credit: Zephyris via Wikimedia Commons

4) The kings of camouflage. Credit: FantasticAnimal via YouTube