Octopus The Master Deceiver

Some animals such as chameleons (and anoles, which are mistakenly called chameleons) are famous for changing their color to match the background. Anoles can change from whitish to gray, brown, or green to match the sand, branches, or foliage where they rest. Some fish can go one better, creating complex disruptive color patterns to match different kinds of blotchy sand, rock, or coral backgrounds. The master of deception, however, is the octopus. No vertebrate can match the octopus in terms of the speed with which it changes color, the number of patterns it can create, or the variety of shapes and textures that it can take on.

Octopuses communicate with one another using complex and rapid changes in color, shape, and skin texture. They can also change color, shape, and texture to threaten, to bluff, or to hide from their enemies. Because they can transform themselves so quickly, octopuses are hard to follow and then hard to find again once lost from sight. They can squeeze into tiny crevices or, in a fraction of a second, turn into what looks like a piece of coral or seaweed or rotting wood—in fact, into virtually anything they might encounter in their environment.

Octopuses are also famous for another trick. When all else fails, they squirt a batch of jet-black ink into the surrounding water. By the time the ink has dissipated and the predator can see again, the octopus is long gone.

so many kinds of animals because no matter where one lives—a desert, a forest, a meadow, or an ocean—the sun shines from above. When looking up toward the sun and sky, dark things stand out and light colors blend in; when looking down toward the ground or the ocean floor, light colors stand out and dark colors blend in. Predators that are countershaded can thus approach their prey with equal stealth from either above or below; likewise, prey species that are countershaded will be equally hard to find whether a predator is searching from on high or from underneath. Countershading and other forms of disruptive coloration can occur in the same organism, so that dark spots, blotches or stripes appear on top while paler ones appear below.

Another way of remaining undetected in a complex scene is by using protective mimicry, that is, to mimic an inanimate object in both color and form. Some insects look like thorns on plant stems; others look like leaves or twigs or flowers. Some insects, frogs, and fishes look like rocks, lichens, or corals. Sea lions, sea dragons, and even eels can look like floating kelp or other forms of seaweed.

Some animals may not look much like the objects around them, but will disguise themselves by attaching pieces of plants or sand or other de-

bris to their body. Some caterpillars use silk to tie bits of flowers and leaves to their body; others use saliva as a glue. Some crabs glue broken bits of shell and coral to their own exoskeleton. By using bits of local materials to camouflage itself, an animal can ensure that it matches the background. It can even change its disguise as it moves from one area into another.

Being transparent is another way to match whatever background happens to be present. Many marine invertebrates such as worms, jellyfish, and shrimp, are completely transparent. Complete transparency is less common among land animals, but some land invertebrates have transparent body parts, such as their wings, allowing them to break up the outline of their body and blend into whatever happens to be in the immediate background.

The Behavior and Ecology of Crypsis

Behavior is an important factor in the success or lack of success of any form of crypsis. For example, not even disruptive camouflage can hide something that is moving quickly with respect to its background. Because of this basic fact, predatory species that rely on speed or stamina to outrun, outswim, or outfly their prey generally have little use for camouflage. On the other hand, so-called sit-and-wait predators (such as boa constrictors or praying mantises), must be virtually perfectly camouflaged in order to remain undetected while their prey approach to within grabbing distance. In between are the stealth hunters that sneak up on their prey before making a final high speed attack; such animals must be camouflaged and slow moving when out of attack range, but do not have to be camouflaged or slow when at close range.

As with predators, prey species that rely on rapid escape maneuvers do not often bother with camouflage coloration, while prey species that cannot rely on efficient escape tactics must, instead, rely on not being seen in the first place. Prey species that can move quickly but not as quickly as their predators must detect their predators before their predators detect them, and then they must remain absolutely still until the danger has passed.

Some species use different strategies as they go through different stages in life. In many altricial species (species with dependent young that re quire extended parental care of the offspring), the eggs and/or young are camouflaged, even though the adults are not; the temporary spots on deer fawns and mountain lion cubs are examples. In other species, nesting or brooding females may be camouflaged while the adult males retain their gaudy plumage or attention-getting behaviors; the changing seasonal patterns of color and behavior of ducks and songbirds provide examples here. Some species may be toxic and gaudy during one stage of life, yet tasty and cryptic during another.

Finally, although camouflage is usually thought of as a visual phenomenon, crypsis is important in every sensory modality. If a prey animal is virtually invisible to its predators, but puts out a sound, a scent, or a vibration that makes it easy to locate, visual crypsis alone would be useless. For successful protection, prey species must be cryptic in whatever sensory modalities their predators use for hunting. Likewise, for successful hunting, predatory species must be cryptic in whatever sensory modalities their prey use to detect danger. For most species of both predator and prey, this

Zebras Predators And Prey

Zebras'stripes not only help them blend into their grassland habitat but also make it difficult for predators topickout a single individual for attack. (Digital Stock)

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