Opposite of predator, you have prey — the animals predators hunt and eat. Prey animals can be anything from the smallest insect to a 1400 pound bull moose. Some prey animals are herbivores, meaning they eat plants. Other prey species are omnivores, which means they will eat plants or animals.

Most times, the word predator brings to mind an image of snarling teeth and slashing claws. While many predators fit this image, many others do not. Predators come in many sizes and shapes. They can be as tiny as a bug or as large as a polar bear. What does a ladybug eat? You're right, other animals! What about that beautiful American robin that we welcome spring with? Yes, another predator! Are you getting the idea? Predators are animals that eat other animals. They're not bad guys. They're just creatures trying to feed themselves; they get hungry just like you and me. “Making a living” to them is finding enough food to eat. They don't have the option of going to the grocery store or the drive-in.

The Role of Predators

Predators are part of a food chain, the process of passing energy from one organism to the next. Plants are the first link in the food chain; they use the sun's energy to make food. Plants are called the producers.

Plant eaters, also called herbivores, enter the picture next. Predators such as birds and foxes join the food chain by eating the plant eaters and are known as primary consumers. These predators may become food for the next animal up the chain.

Predators that eat primary consumers are known as secondary consumers, which are also eaten by tertiary consumers or quaternary consumers. All of these are just layers of animals that eat from the lower layers. Finally you have your apex predator. This is the predator at the top of the food chain.

Most natural communities have several food chains that interconnect. This is called a food web. When a food web is drawn, 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.

A food chain or a food web 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.

Balance of Nature

The relationship between predators and prey is often described as the balance of nature. A natural ecosystem does have a degree of balance — the number of plants and animals in an ecosystem tends to remain within a certain limit, which is not too great or not too small.

Predators, however, are not the only factor that affects a population. A variety of things cause the abundance of a species, including predators, food availability, the competition with other species, disease, and even the weather.

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 their respective numbers to rise and fall.

Where Do Predators Live?

Predators can be found on any continent of the world. Hot desert climates, icy cold polar climates, rainforests, jungles, mountain tops, valleys, oceans, and lakes. Predators are found in nearly every habitat known to us.

Vertebrate Predators

Animals with an internal skeleton made of bone are called vertebrates. Vertebrates include mammals, amphibians, reptiles, birds, and fish.

Although vertebrates represent only a very small percentage of all animals, their size and mobility often allow them to dominate their environment.

Invertebrate Predators

Animals that do not have a back bone are called invertebrates. Invertebrates are cold-blooded — this means their body temperature depends on the temperature of their environment.

Some major groups of invertebrates include amoebas, sponges, jellyfish, corals, tapeworms, flukes, insects, arachnids, crustaceans, mollusks, and echinoderms. There are more species of invertebrates than any other group on the earth. Learn more about invertebrates and find out about the kinds of animals that fall into this category by visiting The National Wildlife Federation.

Carnivorous Plants

Did you know there are even plants that are “meat-eaters”? The Venus fly trap is one you've probably heard of. They are small plants found in North and South Carolina. They grow in nutrient poor soil, so they need insects to provide what they need to survive.

In Idaho, we have two carnivorous plants, sundews and bladderworts. They can be found in bogs near wetlands. Each plant has unique ways to catch and eat food. To learn more about carnivorous plants, visit botany.org.

Hunting Strategies

The way a predator hunts, catches and kills food is determined by many factors such as the adaptations of the predator and the prey, and the type of habitat they live in. The strategies commonly used by predators are:

The Chase

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.

The Stalk

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 Ambush

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 ambushhunters are fairly small because a successful ambush depends on the predator avoiding detection until it strikes.

Teamwork

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!

Prey animals need to be eaten to maintain a balanced and healthy ecosystem. Without these animals being consumed, predators would starve or have to compete for plant food. Without being preyed upon, overpopulation would occur, and prey would most likely eat all available food, ultimately starving themselves to death. 

Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centres that contain green chlorophyll pigments. In plants, these proteins are held inside organelles called chloroplasts, which are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane. In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. The hydrogen freed by the splitting of water is used in the creation of two further compounds that serve as short-term stores of energy, enabling its transfer to drive other reactions: these compounds are reduced nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP), the "energy currency" of cells.

In plants, algae and cyanobacteria, long-term energy storage in the form of sugars is produced by a subsequent sequence of light-independent reactions called the Calvin cycle; some bacteria use different mechanisms, such as the reverse Krebs cycle, to achieve the same end. In the Calvin cycle, atmospheric carbon dioxide is incorporated into already existing organic carbon compounds, such as ribulose bisphosphate (RuBP).^[5] Using the ATP and NADPH produced by the light-dependent reactions, the resulting compounds are then reducedand removed to form further carbohydrates, such as glucose.

The first photosynthetic organisms probably evolved early in the evolutionary history of life and most likely used reducing agents such as hydrogen or hydrogen sulfide, rather than water, as sources of electrons.^[6]Cyanobacteria appeared later; the excess oxygen they produced contributed directly to the oxygenation of the Earth,^[7] which rendered the evolution of complex life possible. Today, the average rate of energy capture by photosynthesis globally is approximately 130 terawatts,^[8][9][10] which is about three times the current power consumption of human civilization.^[11] Photosynthetic organisms also convert around 100–115 thousand million metric tonnes of carbon into biomass per year.^[12][13]

Charles Elton pioneered the concept of food cycles, food chains, and food size in his classical 1927 book "Animal Ecology"; Elton's 'food cycle' was replaced by 'food web' in a subsequent ecological text. Elton organized species into functional groups, which was the basis for Raymond Lindeman's classic and landmark paper in 1942 on trophic dynamics. Lindeman emphasized the important role of decomposer organisms in a trophic system of classification. The notion of a food web has a historical foothold in the writings of Charles Darwin and his terminology, including an "entangled bank", "web of life", "web of complex relations", and in reference to the decomposition actions of earthworms he talked about "the continued movement of the particles of earth". Even earlier, in 1768 John Bruckner described nature as "one continued web of life".

Food webs are limited representations of real ecosystems as they necessarily aggregate many species into trophic species, which are functional groups of species that have the same predators and prey in a food web. Ecologists use these simplifications in quantitative (or mathematical) models of trophic or consumer-resource systems dynamics. Using these models they can measure and test for generalized patterns in the structure of real food web networks. Ecologists have identified non-random properties in the topographicstructure of food webs. Published examples that are used in meta analysis are of variable quality with omissions. However, the number of empirical studies on community webs is on the rise and the mathematical treatment of food webs using network theory had identified patterns that are common to all. Scaling laws, for example, predict a relationship between the topology of food web predator-prey linkages and levels of species richness.