Keystone Species

The concept of keystone species—organisms that have disproportionately large impacts on their ecosystems—was discovered through studies of purple starfish in Pacific tidepools.

During a trophic cascade, the disappearance of a keystone species, which plays an indispensable role in ecosystems, triggers a domino effect within food webs that disrupts the populations of many more species.

Although ecologists have struggled to identify a species as a keystone—one of outsized importance to its ecosystem—an analysis of 50 years of data and 157 studies identified 230 such species.

In Yellowstone National Park, gray wolves act as keystone predators by controlling elk and deer populations, which had previously overgrazed and disrupted river systems that supported many more mammal, fish, and avian species.

By targeting a diverse range of sick and injured marine life, sharks—a type of predatory keystone species—help keep ocean gene pools healthy and promote biodiversity by keeping prey species in check.

Able to hold their breath for up to 15 minutes, beavers are considered keystone species via their construction of dams and formation of wetlands, which serve as homes and food sources for fish, birds, insects, and other animals.

Possessing trunks that contain about 40,000 individual muscles, African elephants act as keystone species by trampling and clearing trees, making pathways in forests, digging water holes, and spreading seeds.

As part of the up to 15 pounds of seafood they consume daily, sea otters eat urchins that feed on kelp forests—sources of shelter and food to over 800 species—thereby making the marine mammal a keystone species.

The jaguar is the largest feline in the Americas and serves as a keystone species by acting as an apex predator with a diverse diet across multiple environments, thereby regulating the populations of dozens of species.

Contributing to one in every three bites of food consumed by humans, bees are a keystone species because of their essential role as pollinators of about 80% of all flowering plants worldwide.