![]() Instead of other animals, horses eat mainly grasses and plants. So where do horses end up on the food chain? Although people sometimes say they're “hungry enough to eat a horse," surely there aren't any animals out there brave enough - or hungry enough - to actually eat a horse… or are there?īelieve it or not, horses are prey animals. Still others, such as humans, eat both meats and plants. Some animals - called "carnivores" - eat only meat, while others - called "herbivores" - eat only plants. Of course, many animals are a source of food for other animals, too. Plants are a source of food for many animals. Sunlight allows plants to make food and grow by photosynthesis. The series of predator- prey relationships in an ecosystem is called a " food chain." Usually, all food chains start with the sun, which provides light and heat. ![]() If a cow eats grass, the cow would be the predator, and the grass would be the prey. However, the same terms can be applied to animal-plant relationships. People usually use the terms predator and prey to refer to animals. If a lizard eats the spider, though, it becomes prey. For example, a spider hunting for insects is a predator. Of course, some animals can be considered both predators and prey. Those that are eaten or hunted are called " prey." Examples of prey animals include zebras, fish and rabbits. Those that do the eating or hunting are called "predators." Examples of common predators include lions, bears and foxes. It is a simple fact of life that some species eat others. The introduction of a predator can decrease species coexistence.In every ecosystem, there is a complex set of relationships between species. These researchers tested this hypothesis and found that, on the contrary, populations of a prey species were reduced after a predator was introduced - not by getting eaten, but by shifting habitat to avoid the introduced predator. "It's so rare in ecology to be able to manipulate whole ecosystems," Pringle says.Īdds Betsy von Holle, a program director in NSF's Division of Environmental Biology, which funded the research, "classic ecological theory suggests that predators promote prey diversity by reducing populations of abundant prey species. The biologists introduced the other two lizards separately or in combination. The brown anoles were established on all 16. The researchers traveled to 16 small islands in the Bahamas, which they used as experimental ecosystems. The results appear in the journal Nature. ![]() To tackle the question, the team used three lizard species: the predatory curly-tailed lizard and two prey species, green anoles and brown anoles. "The ways in which prey change their behavior to avoid getting eaten is a hard thing to predict, but without understanding that, you can't predict anything else." ![]() "You can't understand predator-prey interactions - or how predators will affect biodiversity and ecosystems - without understanding the behavior of the prey," says Pringle. The destruction is usually blamed on the predator's eating choices, but sometimes the key is the prey animals' responses, according to a team of researchers led by ecologist Robert Pringle at Princeton University and colleagues at the University of Florida and other institutions. In fact, a leading cause of extinction is the introduction of predators into an isolated place like an island or a lake. Invading predators can devastate an ecosystem.
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