Defense and Offense


Animals and plants have many ways of influencing their relationships with each other. The great game is to get what you need while avoiding being what somebody else needs.

Barrel cactus

Many plants and most animals have physical defenses to ward off the itinerant browser. Everyone knows about the spines on cacti and the thorns on roses, not to mention the claws on cats and the spikes on porcupines.

Many plants and animals also produce poisons and irritants which drop them down to second or third on everybody else's shopping lists. Even as basic a talent as running fast is a defense mechanism (or an offensive weapon, in the right circumstances).

One of the most interesting ways that animals control their interactions is through coloration. There are two basic coloration strategies: hide or advertise. Then there are the sneaky ones who take advantage of someone else's coloration defense.

Camouflage is a coloration pattern designed to hide the presence of the organism. Actually, camouflage itself (being colored to match your background) is only one of several strategies of this type, but we'll just call them all camouflage. Some organisms simply match the backgrounds of their normal habitats. For example, the overwhelming majority of wild gerbils are brown just like the dirt they hide against. Some organisms, like the chameleon, can actually adjust their body color to a certain extent. There are other coloration mechanisms which hide creatures. For instance, some animals are colored in irregular or confusing patterns which tend to make the body outline hard to distinguish, thus confusing predators.

Zebras

Zebras seem to be pretty obviously colored, until you see a herd of them all running and jumbling together. Then it becomes very difficult to tell where one zebra ends and the next one begins.

And many, many animals are countershaded. Countershading is a pattern in which the top of the animal is darker in color than the bottom. This is the opposite of the shading pattern produced by sunlight, which is always light on top and dark on the bottom. Since this shading pattern is what makes us see an object as three dimensional, countershading tends to make an animal's body look flat. If the animal stands very still, this can confuse or fool a predator. Ever hear about deer freezing in the headlights? That's their first response to danger stand still, and hope your predator doesn't want a paper thin meal.

Incidentally, though we usually discuss camouflage in prey animals, note that it is just as important for most predators to be as inconspicuous as possible. Think of the coloration of a wolf or a puma.

Tiger

Though it seems unlikely, even tigers are camouflaged. Their natural habitat is tall grassland, in tropical (thus sunny) climates. Their vertical gold and black stripes blend right into the light and shadow effects of tall grass in the sun.

The opposite strategy is to make yourself as obvious as possible. This is often called warning coloration. At first consideration, this seems to be a pretty foolish way for an animal to be colored. If you advertise your presence, then you will surely end up somebody's dinner. There is, however, a catch. Animals with warning coloration usually have some feature to warn about. For instance, one animal with this kind of coloration is the skunk. Now, the skunk has pretty significant claws and sharp teeth, but it's hardly going to be able to fight off a fox or a wolf. And running away is simply not an option they waddle. The skunk's defense is its unpleasant odor which the wolves find just as nasty as we do. The highly noticeable black and white striping of a skunk makes it easy for predators to learn what they look like so while they may try skunk once or twice, they will quickly learn to look for something else to eat. Some skunks die in the learning process, but it is overall a very successful strategy.

Coral Snake

Finally, some animals sneak by on the coat tails of others. Mimicry is the phenomenon in which one animal looks a lot like a different animal. For instance, there is a poisonous snake called the Coral snake which has brilliant warning coloration. Its body is broadly striped in red, yellow and black.

A second snake, the King snake, has a very similar coloration pattern but it isn't poisonous. The nasty experiences predators have with coral snakes also protect the King snake. This piggy back strategy is called mimicry.


Copyright © 2000 College of DuPage
Center for Independent Learning (630) 942-2185
fancher2@cdnet.cod.edu

Updated 25 September 2004