Different animals have different ways of acquiring the food they need to survive. Animals that consume only plants are called herbivores. This way of life, followed by deer, giraffes, elephants, squirrels, and many other creatures, generally requires relatively little time searching for food (plants are often plentiful) and a lot of time eating (plant tissue contains less energy and is often more difficult to digest than animal tissue, so more of it must be eaten). In contrast, carnivores feed only on other animals, and thus generally spend more time searching for food and less time actually eating. Fortunately, meat is energy-rich, so relatively less of it needs to be consumed.

Animals whose diets consist of other animals generally work much harder to obtain food than do animals whose diets consist of plants. After all, plants and seeds cannot run away or resist, while prey animals must first be captured and subdued before they can be eaten -- and most fight tooth and nail to prevent that from happening. In many cases, prey animals have evolved a heightened sense of awareness, speed and agility, or disguises, all of which help them to avoid predators. Keeping pace, many predators have evolved similar traits that make them more effective at catching their food.

In general, carnivores use one of two different predatory strategies in their search for food. The more common of the two is called "active searching." As the name implies, a predator using this strategy goes looking for food. Kingfishers, for example, make dive after dive into lakes, ponds, and streams in an effort to catch fish. Leopards stalk their prey tirelessly, often under cover of darkness. The odds of catching anything are low, but the payoffs, if successful, are high. Many other species of carnivorous mammals, including cats and wolves, also go in active pursuit of prey. Typically, animals that use this strategy have physical or behavioral adaptations that make them more efficient pursuit predators, including speed, endurance, cunning, and highly specialized sense organs or physical features for finding and capturing their prey.

The less common of the two predatory strategies is called "sit and wait." Despite the apparent simplicity of this relatively lazy strategy, some of the animals that use it possess traits that are just as fantastic as the leopard's keen sense of smell or the kingfisher's aerobatic dives. Mantis shrimp, for example, dig tunnels in the ocean floor from which they emerge with lightning speed to capture passing prey. But mostly, sit-and-wait predators rely on very good camouflage to fool their prey into believing that no danger is near. Flounder and chameleons are good examples. They can change the color and pattern of their skin to perfectly match and blend in with their environment.