Background Essay: Animal Defenses

To the hunted, the world must seem filled with predators. Antelope sentries on the African savanna stand guard while other members of the herd graze. Fish form large groups, called schools, as a defense against larger species who would eat them. Many creatures, though, live solitary lives. Without the protection of a group, these creatures seem highly vulnerable to attack. Indeed, they would be if it weren't for the remarkable defense strategies they employ when confronted by a predator.

Prey animals have several strategies to defend against predators. The first is probably the most obvious. It's a strategy most of us have seen used by animals in the wild (you might even have used it a time or two yourself): It's called flight. The strategy is to get away from the predator as quickly as possible, in any way possible, including running, hopping, swimming, or flying. After all, a predator can't eat what it can't catch.

Unfortunately, the flight strategy is effective only for those animals that are faster or more agile than their predators. Even then, it is often used only as a last resort. Sometimes, a more effective strategy is to hide. A well-camouflaged animal, after all, will often go undetected by a passing predator, thus saving the energy it would otherwise have expended in fleeing. Most wild animals benefit at least to some degree from camouflage.

Trickery can also be an effective defense against predators. This method is often used by those creatures unlucky enough to be discovered by a predator and with no way of outrunning or outmaneuvering their chaser. The puffer fish featured in the video segment uses this strategy. Just when the otter is about to grab its victim, the puffer fish expands its body with air or water, making it appear larger and more intimidating than the typical otter meal. When the otter leaves the area, the puffer fish deflates and swims away. Other animals employ the trickery technique by ruffling their feathers or fur to make themselves look larger or by flashing spots that look like large, menacing eyes to frighten away predators.

As a last line of defense, some animals rely on chemicals and/or physical structures to keep predators at bay. The snake depicted in the video segment, for example, at last dissuades the kitten from further attacks by emitting a foul-smelling and foul-tasting chemical and playing dead. Porcupines rely on their quills for protection. These stiff, sharp modified hairs that cover the porcupine's back guarantee to puncture the flesh of any predator that dares to take a bite, and barbs ensure that the quills will stay where they're embedded.