A food chain allows a small amount of the sun's energy to be passed along through each animal. When an animal dies, it decomposes, or breaks down, and provides the soil with nutrients that help plants to transform the sun's energy into food once again.
When a food web is diagrammed, it looks like a pyramid with the apex predator at the top and the plants eaters at the bottom. Plant eaters are the most abundant part of the web.
It is said that the predators in a particular area control the populations of prey species. In this way, the prey species won't overpopulate and destroy the habitat. This seems logical enough, but it is too simple to fully explain what goes on in nature. One thing to remember is that populations of predators and prey do not remain constant. There are many factors which cause the numbers to rise and fall.
Balance of Nature
Nature does have a degree of balance; the number of plants and animals tend to remain within a certain limit, which is not too great or not too small. Predators, however, are not the only factor of population control. A variety of things cause the abundance of a species, including predators, food availability, competition with other species, disease and even the weather.
Hawks are among the many predators that catch their prey by chasing it. Chasing takes both time and effort to make a successful capture. To be successful, predators that chase their prey must concentrate on species that will provide enough nutrition to offset the energy burned while chasing. This is one reason why the hawk tends to eat more rodents and birds than grasshoppers. Grasshoppers just don't provide enough food value to justify the effort it takes to catch them.
Herons use a different technique, the stalk. Standing motionless in shallow water or wading slowly along the shore, the heron patiently searches for prey. When a heron sees its prey it captures it with a quick lunge of its long, sharp beak. This method does not require much energy. The downfall is the amount of time it takes to search for food. A stalking predator can afford to choose smaller prey and still meet its energy requirements.
The alligator prefers to lie still and wait. This method of hunting requires little effort, but chances of getting food are low. The cold-blooded alligator has minimal energy requirements. It can get by with infrequent meals. Most ambush hunters are fairly small because a successful ambush depends on the predator avoiding detection until it strikes.
Some animals hunt in teams. Wolves, lions, hyenas, coyotes and killer whales will usually live and hunt in family teams. Not only can they pursue larger and sometimes faster prey, but family groups can protect their little ones from other large predators. There's even a tropical insect that hunts as part of a team. South American army ants travel in the tens of thousands and devour every living thing in their path; insects, snakes, livestock, rats and mice. There aren't many creatures that can withstand marching army ants!
Vision is often the most important sense for a predator. A predator's eyes are usually located in front of its head. The forward location of the eyes gives binocular-type vision. The area that each eye sees overlaps so the brain receives two slightly different messages about the same scene. This will help a predator determine how far away prey is. It also tells the predator how fast its prey is moving.
Birds and insects must have the ability to catch prey in the air. A bird of prey's telescope-like vision can be eight times stronger than ours. Some predators rely on more sets of eyes than just one! Spiders and scorpions have clusters of six to eight eyes. Some of the eyes form the image. Others estimate distance, and still others detect motion. It's amazing though, even with eight eyes, a spider can only see about 1 foot in front of its face.
Predators which hunt at night (nocturnal predators) have special mirror-like structures in the back of their eyes. These structures help the animal to see in the dark. Deep sea animals have the same structures.
Most predators have a very good sense of hearing. In mammals, external ear flaps can be swiveled forward or backward in order to pinpoint the direction of a sound. The ears of bats are often highly specialized, with strange shapes that help catch the echoes of the calls they make as they fly. Birds can hear very well, too. Owls are thought to have the most outstanding hearing of any animal. Their ears are offset, which means one is higher than the other.
This is another way to pinpoint the source of the sound. Some animals don't need ears to hear. Instead, they rely on vibrations they feel in their bodies. Ground vibrations from moving prey animals are transmitted through the bones of salamanders and snakes to the nerves near their ears. Sharks can monitor vibrations in the water with a lateral-line system. Fluid-filled canals lie just beneath the shark's skin along the sides of its head and body. The canals are filled with small pores open to the water. Underwater noises or motion cause a vibration that strikes these open pores. A shark tunes into the vibration and looks for its next meal.
Some predators can smell a meal from a mile away! Foxes are even able to smell food which is buried under two feet of soil. Some use their sense of smell to follow the footsteps or tracks of an animal.
A shark has outstanding smelling ability, but it works a bit differently. Their nostrils are not for breathing, but are used for sensing odor. Water flows in and out of the nostrils. A shark is able to identify the different smells found in the water. Amazingly, a shark can smell its prey from 2 miles away!
Snakes use their tongues to smell. You might see a snake flicking its tongue around. The snake is not getting ready to bite, it is smelling the air by picking up dust particles. These particles are carried to taste detectors in the snake's mouth. The taste tells snakes what animals are near.
These are used to help kill the prey and are used for "knives and forks" while eating the prey. Most animals have three kinds of teeth. In the front, you'll find incisors. These are used to cut food. On the sides, you'll see longer teeth which are used for tearing chunks of flesh off of the prey. Canine teeth can also be used to kill the prey by piercing the neck or throat. Molars are found towards the back of the mouth. They are flat and strong and used to chew or grind. Some animals, such as crocodiles and sharks, have long, cone shaped teeth. These are used for grasping the prey and pulling it underwater. When underwater, the prey will drown enabling the predator to eat it.
Jaws, as well as teeth are important adaptations to seize and subdue their prey. Powerful muscles provide leverage and gripping power at the front part of the jaws. Some snakes are able to unhinge their jaws. This allows them to swallow a meal which is much larger than the snake's own head!
In some cases, beaks take the place of teeth. Each beak tells a story about its owner. Long beaks are used for probing, hooked beaks for tearing, thick ones for crunching seeds, thin ones for picking insects. Beaks provide birds with a lightweight alternative to a mouthful of teeth - like hollow bones, they are an adaptation for flying.
Sharp claws are also powerful weapons. Birds of prey have powerful claws, called talons which help the raptor to grab its prey. Most big cats have claws that they use to grip and tear. They are able to pull in these claws when walking or running. This keeps them sharp. Moles and hedgehogs use their claws to dig up insects. In the same manner, grizzly bears dig up roots and burrowing rodents. Of course, on the grizzly, the claws are on the "tip of the weapon." A grizzly's powerful paw can bring an animal down with one swipe.
Some predators use their tongue as an effective weapon. A chameleon has one of the fastest tongues. It shoots its sticky tongue out towards the prey, which is coated with a glue-like substance which captures and swallows the prey. Did you know anteaters have tongues as long as a person's arm? This adaptation helps an anteater to reach areas where he or she needs to reach.
Another hunting weapon is poison. Snakes use their poison, which comes from their fangs, to paralyze or kill their prey. A spider releases strong digestive enzymes that turn the prey's insides to liquid. A straw-like mouth enables the spider to suck up the liquid. Wasps and scorpions paralyze their prey by using powerful stingers. A jellyfish uses its deadly tentacles.
3. Disruptive Coloration
Nature provides three types of camouflage.
A third type of camouflage is called disruptive coloration. A zebra has disruptive coloration. Its stripes help it to hide when it is grazing near trees and bushes. Does a tiger have disruptive coloration, as well? Why?
Some animals change color with the season. This helps them to blend in with their surroundings when their surroundings change. Imitation is another form of camouflage. Some animals look like other animals. For the most part, this helps prey species. Bright coloration which seems opposite of camouflage, is it actually is used to warn animals to stay away. Brightly colored animals may be poisonous or have an unpleasant taste.
Many thanks to Idaho Fish and Game and Project WILD for their partnership and assistance in this project. Information for this site is copyrighted by Idaho Department of Fish and Game and Idaho Project WILD. Permission has been obtained and granted to use this material for educational purposes. Photographic images were provided by the Department of Fish and Game and various other sources.