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

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.

Sea otters act as keystone predators by eating up to 15 pounds of seafood a day, including urchins, which feed on kelp forests that support over 800 species by providing them with habitats and food.

During a tropic 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.

In Yellowstone National Park, grey 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.

As environmental engineers—a main type of keystone species—prairie dogs support over 150 other species through their grazing habits and burrowing of underground tunnels, which serve as habitats for owls, snakes, ferrets, insects, and other organisms.

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.

Some invasive species can provide benefits to ecosystems over time

In the 1990s, round gobies were introduced into the Great Lakes, rapidly spreading and competing with local sculpin and logperch. However, Lake Erie watersnakes, which were on the endangered species list, shifted their diet to be almost entirely made up of the plentiful round gobies, contributing to their loss of endangered status in 2011.

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.

Benign species can become invasive if introduced into predator-free habitats

Most ecosystems contain organisms that, over many generations, have evolved into a stable balance with one another and their surroundings. In a new environment, a species may no longer be restricted by the limiting factors it is used to, and the native organisms in the area may not adapt quickly enough to the invader to establish a new balance.

While invasive species typically harm ecosystems by outcompeting native organisms for resources, some provide unexpected benefits, including new shelters, nesting habitats, and reduced environmental heat stress.

Plastic debris across the ocean aids the spread of invasive species

The durable, long-lasting material can serve as a platform for living organisms to latch onto and ride over vast distances. After the 2011 earthquake and tsunami in Japan, a large dock carrying 100 tons of living organisms native to Japan washed up on Oregon's coastline, confirming the ecological threat.

Fungi have been used to restore island habitats in the central Pacific

After removing 1.5 million invasive coconut palm trees and eradicating the black rats that fed on them, as well as seabirds and crabs, conservationists working with the US Fish and Wildlife Service identified areas where fungi could be transplanted to provide nutrients to native trees. These trees serve as nesting sites for seabirds whose guano nourishes coral reefs.

Starfish are invertebrates—they lack a backbone—and while most exhibit pentametric radial symmetry due to having five arms radiating from a central disk, some can possess more than 40.

Fig trees are considered keystone species because they provide year-round habitat and fruit, which are eaten by an estimated 1,300 species of birds and mammals worldwide.

The Southern Ocean's powerful circular current isolates organisms in its environment

The spiralling current churns up nutrients across the frigid waters, leading to the evolution of fantastical organisms, including century-old starfish and colossal squid, and unique adaptations, including the icefish's clear blood and organic antifreeze, over the past 30 million years.

Synthetic pheromones may protect coral reefs by attracting their predators

Researchers in Australia and Japan have developed these nontoxic chemicals to attract crown-of-thorns starfish, which consume corals that make up the Great Barrier Reef. As of 2026, synthetic pheromones have been shown to be effective in lab trials, and future field trials will attempt to lure starfish into areas for mass removal.

Over 1 million fish, marine mammals, and invertebrate species depend on coral reefs for habitats, camouflage, and food.

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.

Microbial research suggests shifts in diverse populations may help an invasive species establish itself

In 1958, English ecologist Charles Elton suggested that diverse ecosystems should be more resistant to invasive species because gaining a foothold would be more challenging when resources are more thinly spread. However, in lab-grown microbial ecosystems with greater biodiversity, population volatility opened more ecological roles that invasive species could easily fill.

The world's largest species of marine algae is giant kelp, which can grow as much as two feet per day from depths of about 100 feet up to the ocean surface.

What revisiting a 1979 experiment reveals about ecosystem recovery after deep-sea mining

A 2023 study co-led by the National Oceanography Centre and the Natural History Museum, London, found that tracks made by the mining vehicle remained largely unchanged since 1979. Small animals, such as amoeba-like xenophyophore, were seen in the cleared areas, but sightings of larger animals known to live in the region were much rarer. (Some readers may experience a paywall.)

Forever chemicals accumulate up the food web, with recent research indicating that apex predators have higher concentrations because they're eating prey that also have accumulated the substances.

Studying the circadian clock of a tiny swimming polar creature may help forecast polar ecosystem health

A 2025 study found that Antarctic krill, a food chain staple in the Southern Ocean, have an internal biological clock that helps regulate its swimming patterns and helps the tiny shrimp-like animals adapt to daily and seasonal environmental changes. Better understanding of how the clock and light cues interact may help scientists understand how well the species will respond to pronounced climate change in the polar region.

John Steinbeck's philosophical ideas, which he often explored in his novels, wrestled with the role of the individual and the power of community.

Invasive species are the third biggest threat to Earth's biodiversity

According to the World Wildlife Fund's Living Planet Report 2020, changes in land and sea use account for about half of all recorded threats to the diversity of the planet's species. Species overexploitation is the second-largest proportional threat at 24%, while invasive species make up 13%.

Nearly all species introduced into a new environment are not invasive

Introduced by zoologist Charles Elton in 1958, the term "invasive species" refers to organisms that are not native to an environment but cause harm after their introduction. Some ecologists argue that terminology such as "native" and "non-native" may only serve to assist in extinction when legislation is limited to protecting "native" organisms.

Invasivorism is a form of ethical eating focused on eating invasive species

The culinary approach helps combat the growth of invasive species populations by increasing demand for dishes made with them, but some suggest that creating a market for these species may help prolong their presence by moderating control. Some diners have expressed reluctance toward consuming more exotic species, such as nutria—raccoon-sized rodents.

Multiple species exhibit convergent evolution by developing crab-like features

Various organisms that appear to be different types of crabs, such as porcelain crabs and coconut crabs, have been shown to belong to distinct decapod lineages whose predecessors resemble shrimp or lobsters. Environmental pressures and other factors have caused these species to develop similar characteristics, which nature has shown are beneficial to survival.

Despite being multicellular and photosynthetic, organisms such as kelp and sea moss are macroalgae, not plants, because they lack specialized roots and stems to pump water.

The deep-sea fangtooth has the largest teeth of any marine species relative to body size

From transparent fish to the heaviest worms on the planet, these seven creepy creatures lurk in the deep sea. Learn all about them and the unique traits that help them survive and hunt.

Deep sea fish rely on a molecular strengthener to prevent being crushed

Trimethylamine N-oxide (TMAO) stabilizes hydrogen bonds and prevents water and proteins within organisms from being misshapen under immense pressure. Compounds called piezolytes protect cellular membranes from being crushed in regions like the Mariana Trench, where pressures are 1,100 times greater than surface atmospheric pressure.

One NHL team tosses salmon to its fans

Detroit Red Wings fans have thrown octopuses on the ice since 1952, and fans of other teams have tried their own hand at tossing things in the rink ever since. It's now become a calling card for the Seattle Kraken, whose fans nod to the city's Pike Place Market by tossing salmon onto the ice.

The most effective method of managing invasive species is prevention education

Controlling a spread after a species has become established in an area is much more costly and time-consuming than early detection and rapid response. Control methods include the purposeful introduction of predators, the use of pesticides, herbicides, fungicides, and insecticides, and physical collection and removal.

John Steinbeck often drew a pig with wings next to his signature, a character he affectionately called 'Pigasus.'