Many predators are thought of as “bad” because they kill the animals below them in the food chain. A lot of these animals are also thought to pose more of a threat to us than they actually do. These animals aren’t bad because they eat other animals.

In fact, they play a very important role within their ecosystems. 


Some predators are considered keystone species, which means that they influence the proper function of their ecosystem and cause what is known as a trophic cascade.


What is a Trophic Cascade?

A trophic cascade is what happens when predators keep their prey in check. This can mean that they make sure they don’t overpopulate or they keep them moving around so they don’t overeat and destroy the vegetation around them. This allows for the prey species below their prey to survive better.1


In order to be considered a trophic cascade, the impact must reach across at least three levels of the food chain.1

For example:

     Wolves eat elk → elk eat the vegetation

     Because wolves eat the elk, the vegetation benefits.


Wolves keep the elk populations in check and stop overgrazing, which means that the vegetation can thrive and recover. When keystone species aren’t around to do their job, vegetation can disappear entirely.1


What Are Some Keystone Species?

Keystone species tend to be predators. Sometimes they’re apex predators, at the top of the food chain, but not always.


Some examples of keystone species that are also apex predators are:

  • Wolves

  • Sharks

  • Cougars

  • Tuna2


Other examples of keystone species are:

  • Sea otters

  • Blue crabs

  • Starfish

  • Prairie Dogs1&3


These animals all have the same effect on their environment. They maintain productivity and biodiversity.1 For example, sea otters prevent sea urchins from destroying kelp beds, blue crabs keep snails from destroying salt marshes, and starfish keep mussel populations in check.1&3


Why Are Trophic Cascades and Keystone Species Important?

Everything needs to work together in order to keep an ecosystem in balance. When an environment is healthy, there’s biodiversity and sustainability. When key species are removed, a breakdown of stability can occur.1


It’s not enough to just protect habitats. We need to also protect the species within those habitats, too.3 These species interactions are important for every level of the food chain to thrive. When overgrazing occurs, biodiversity is threatened and the ecosystem overall is less productive.1 Our predators are an important piece of the puzzle to make sure everything is working as it should.


Love our predators? Check out our blog post on Mountain Lions here!

All the best,
Chris & the WERC Team

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