Why are Keystone Species Important? 3 Roles They Play

Why are keystone species important?

Any arrangement or community’s “keystone” is regarded as one of its most important components in that ecosystem. A keystone species is an animal that keeps the fabric of an ecosystem—marine or otherwise—together.

Ecosystems would seem extremely different without their keystone species. If a keystone species vanished, some ecosystems might not be able to adjust to environmental changes.

That might lead to the ecosystem’s demise or might let an invading species take control and drastically change the ecosystem’s course.

Since the term “keystone species” is not formally defined, experts may disagree about whether plants or animals in a specific environment are deserving of the honor. Some wildlife biologists claim the idea oversimplifies the role of one species or plant in complex ecosystems.

However, referring to a certain plant or animal as a keystone species can assist the general public appreciate how crucial one species can be to the existence of many others.

Why are Keystone Species Important? 3 Roles They Play

Many scientists mention three categories of keystone species:

  • Predators
  • Ecosystem Engineers
  • Mutualists


Predators aid in the management of prey species’ numbers, which has an impact on the number of plants and animals farther up the food chain. For instance, sharks frequently eat sick or old fish, allowing healthier species to flourish.

Sharks can prevent smaller creatures from overgrazing and eradicating seagrass beds only by being present near those areas. Research on the impact of a marine predator on its habitat served as the basis for the entire keystone species concept.

The removal of a single species, the Pisaster ochraceus sea star, from a tidal plain on Tatoosh Island in the U.S. state of Washington has a profound impact on the ecology, according to research by American zoology professor Robert T. Paine.

On Tatoosh Island, purple sea stars, also known as Pisaster ochraceus, are significant barnacle and mussel predators. After the sea stars disappeared, mussels moved in and displaced other species, such as the benthic algae that supported populations of sea snails, limpets, and bivalves. The tidal plain’s biodiversity was reduced in half within a year due to the lack of a keystone species.

Ecosystem Engineers

An organism that alters, destroys, or creates new habitats is known as an ecosystem engineer. The beaver is likely the best illustration of a keystone engineer. Beavers cut down old or dead trees along riverbanks to utilize building their dams, which is essential to the health of river ecosystems.

This enables an abundance of new, healthier trees to sprout. River water is diverted by the dams, resulting in wetlands where a variety of animals and plants can flourish.

Beavers, African savanna elephants, and other ecosystem engineers build, alter, or maintain the environment around them instead of affecting the food source. They affect the presence and behavior of other creatures and contribute to the habitat’s overall biodiversity.


Mutualists are two or more organisms that cooperate for the benefit of the environment as a whole. One of the best examples of this is bees. In addition to collecting nectar from flowers, bees also transport pollen from one flower to the next, increasing the likelihood of fertilization and promoting more flower growth. The main food sources for bees themselves are nectar and pollen.

Other keystone species groups are recognized by some scientists. Predators, herbivores, and mutualists are on one additional list. Another lists resource competitors, mutualists, and predators.

Plants can be considered keystone species. For example, mangrove trees play a crucial function in stabilizing shorelines and preventing erosion along numerous coastlines. Their roots, which extend down through the shallow water, also offer a shelter and a feeding location for little fish.

Often, it takes the extinction of a keystone species for the importance of that species in an ecosystem to be fully understood. Robert Paine, an ecologist who popularized the phrase “keystone species” in the 1960s, discovered the significance of such species while researching starfish along Washington state’s rugged Pacific coast.

Because the starfish consumed mussels, the population of mussels was kept under check, allowing many other species to flourish. As part of an experiment, the starfish were taken out of the area, which caused the mussel population to explode and drive out other species.

The ecosystem’s biodiversity was severely diminished. According to Payne’s research, finding and safeguarding keystone species can assist in maintaining the population of numerous other species.

An indigenous plant species and a species of hummingbird work together as keystone mutualists in the wooded grasslands of Patagonia (near the southernmost point of South America). Local trees, shrubs, and flowering plants have developed to rely only on the green-backed firecrown hummingbird Sephanoides sephanoides for pollination.

20% of the area plant species are pollinated by green-backed firecrowns. The sugary nectar that makes up the majority of the hummingbird’s diet is then produced by these plants.

Without green-backed fire crowns, portions of the current Patagonian ecosystem would vanish since no other pollinator has developed the ability to pollinate these plants, reducing their functional redundancy to almost zero.


Keystone species influence the variety and abundance of other species in a habitat, helping to preserve the local biodiversity of an ecosystem. They almost always play a key role in the local food chain.

The fact that a keystone species performs a crucial ecological function that no other species can is one of its defining traits. A whole ecosystem would drastically change—or vanish altogether—without its keystone species.

It’s crucial to remember that a species’ function might vary from one ecosystem to the next, and a species that is valued as a keystone in one place might not be in another.


Editor at EnvironmentGo! | providenceamaechi0@gmail.com | + posts

A passion-driven environmentalist by heart. Lead content writer at EnvironmentGo.
I strive to educate the public about the environment and its problems.
It has always been about nature, we ought to protect not destroy.

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