Masters of Disguise
Published April 09, 2015
Under the water, things aren’t always as they seem.
By: Elizabeth Bastos
The scientific definition of camouflage is “the use of any combination of materials, coloration or illumination for concealment, either by making animals hard to see or by disguising them as something else.”
The colors, shapes and patterns of camouflage can be gorgeous wild beauty, but camouflage is an evolutionary tool, an edge up in the game of survival. Prey animals need to conceal themselves and avoid being eaten, and predators need to hide their true intentions.
The decorator crab, for example, does its best to resemble a rock. It chooses bits of seaweed and other adornments—even small sponges and anemones—and attaches them to the Velcro-like surface of its back to become a living landscape, to fool its predators into believing there’s “nothing to see here” but another rock among rocks.
Some species possess the unique ability to change color, brightness, hue and even the texture of their skin. They can match any background instantly and exactly, from bumpy red coral to the wavy pattern of sun on sand. Certain cephalopods—squids, octopuses and cuttlefish, for example—exhibit some of the most flamboyant visual camouflage in the animal kingdom.
These color-change magicians have thousands of specialized cells in their skin called chromatophores that engineers and materials scientists are studying for human use in buildings and even clothes as cloaking devices.
Flounder also have chromatophores. But unlike the cephalopods, most flounder have only the brown pigment melanin, which we also have in our skin. All we can do with it is tan; a flounder can match a checkerboard.
Dapples. Speckles. Patchy spots and lines. Disruptive coloration is a type of camouflage designed to confuse the eye and muddle the outline of an animal’s body.
Possibly the most extreme example of camouflage is mimicry, whereby an animal resembles another creature. Incredible mimicry is exhibited by the inch-long brightly colored pygmy seahorse, which lives its entire adult life attached to a tropical coral called a Gorgonian sea fan.
The knobby bumps on the seahorse’s body look exactly like the coral’s polyps. Who can say where coral ends and inch-long fish begins? It blends into its home so well, it’s almost invisible.
Countershading is common among animals that live in the sea. It is a useful type of camouflage because it mimics the effects of sunlight in seawater. In counter-shaded animals like the great white shark, the dorsal side of the body is dark and the ventral, or belly, side is light.
Image via WikiCommons
When seen from above, the shark appears murky and blends in with the deep shade of the water. When seen from below, the lighter-shaded belly of the shark dangerously slides into the brighter, sunny surface water.
In the race to become ever more finely adapted to their environments, to lurk unseen and to hide, predator and prey animals continue the evolution of camouflage in beautiful patterns, stripes, dots and stunning skin morphs.