Scientists Say: Predator and Prey

Ecological relationships between predators and their prey help drive the evolution of life

a green chameleon stretches out its long tongue to snag a grasshopper off the leaf of a plant

A chameleon is a predator that uses its long, sticky tongue to snag its prey, a grasshopper.

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Predator and Prey, (nouns, “PREH-duh-tor” and “PRAY”)

The words “predator” and “prey” describe the roles in a relationship between two species. In this relationship, one species eats the other. The predator is the species that does the eating. The prey is the one that gets eaten. Predator/prey relationships are important links in food webs. These links move energy and nutrients through an ecosystem.

A bear fishing salmon from a river is one example of a predator/prey relationship. The bear is the predator. The salmon is the prey. But salmon must eat too. They snack on plankton, insects and other small critters. So in those cases, the salmon plays the role of predator.

Animals aren’t the only predators and prey. A rabbit chomping on grass is a predator, while the grass is its prey. But plants can also play the role of the predator. For example, a Venus flytrap (Dionaea muscipula) snares flies in its leafy jaws and digests them.

Predators and prey drive each other’s evolution. Over time, predators adapt to better catch prey. For example, the cheetah’s powerful body can out-race its impala prey. But prey have evolved ways to avoid being eaten. The nimble impala can make a hard swerve that leaves behind the cheetah. Many plants have toxins, spines or other defenses that make eating them unpleasant. And millions of years ago, the need to escape marine predators likely helped drive some species from water to land.

In a sentence

Thanks to its predator/prey relationship with ants, the Australian ant-slayer spider (Euryopis umbilicata) evolved a cool somersault technique for capturing prey.

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Katie Grace Carpenter is a science writer and curriculum developer, with degrees in biology and biogeochemistry. She also writes science fiction and creates science videos. Katie lives in the U.S. but also spends time in Sweden with her husband, who’s a chef.

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