Apex predator

An apex predator, also known as a top predator or superpredator, sits at the very top of a food chain.

This means they have no natural predators of their own in their environment. Scientists define these animals using trophic dynamics. This concept refers to the different levels an organism occupies within a food web. On land, food chains are often quite short. For example, wolves act as secondary consumers by preying on large herbivores. These herbivores are primary consumers that eat plants, known as primary producers.

Because they occupy the highest trophic levels, apex predators are vital to wildlife management and conservation.

These predators influence entire ecosystems through a process called top-down control. They affect the population dynamics of prey species and other predators. This can happen in both aquatic and terrestrial environments. For example, a study on lakes showed that removing the non-native smallmouth bass allowed the native lake trout to thrive. Once the bass were gone, the trout could diversify their prey selection. In land environments, the badger acts as an apex predator that competes with the hedgehog. The hedgehog is a mesopredator, which is a mid-level predator. When badgers were removed in a trial, hedgehog densities more than doubled.

Predators that exert this kind of control are often called keystone species.

The impact of a top predator can trigger a trophic cascade. A trophic cascade is a series of powerful changes that ripple down through every level of an ecosystem. For instance, when Arctic foxes were introduced to subarctic islands, their hunting of seabirds turned grasslands into tundra. When apex predators are removed, it can cause mesopredator release. This occurs when mid-level predator populations grow rapidly because their competition is gone. In North America, the ranges of all apex carnivores have contracted over the last two centuries. Meanwhile, the ranges of 60% of mesopredators have actually grown.

Even in the ocean, the loss of sperm whales, which have a trophic level of 4.7, caused an increase in large squid populations.

Apex predators have a massive evolutionary history dating back millions of years. They have existed since at least the Cambrian period, roughly 500 million years ago.

While we cannot observe extinct animals, we use indirect evidence to identify them. We look for things like the absence of other predators or specific bite marks on fossils. Anomalocaris was an aquatic apex predator during the Cambrian period. Later, carnivorous theropod dinosaurs like Allosaurus and Tyrannosaurus are theorized to have been top predators. A Permian shark named Triodus sessilis was also found to be high in the food chain. It contained amphibians, one of which had already eaten a fish. This shows the shark lived at a trophic level of at least 4.

Conservation efforts often focus on the importance of these animals. Humans have hunted many apex predators close to extinction, but some are returning. In 1995, gray wolves were reintroduced to Yellowstone National Park. This move caused dramatic changes in the Greater Yellowstone Ecosystem. The wolves preyed on elk, which changed how the elk moved and grazed. This allowed plants like willow and aspen to grow back in riparian zones. These plants created new habitats for beavers and moose. Even grizzly bears benefited by scavenging wolf kills during the autumn. This extra food helps bears prepare for hibernation and may increase the number of cubs born.

There is an ongoing scientific debate about whether humans are apex predators. Some ecologists calculate a fractional human trophic level (HTL) based on diet. In 2013, researchers found an average HTL of 2.21 globally. This value is similar to non-apex animals like pigs or anchovies. This low number comes from terrestrial farming where humans eat many plants and herbivores. However, other scientists argue that humans are apex predators in marine systems. In Caribbean coral reefs, humans have a trophic level of 4.65. In the Benguela system near South Africa, the level is 4.5.

These higher numbers suggest that when humans eat predatory fish, they act as top predators.

Humans have also interacted with apex predators for thousands of years. For 40,000 years, humans have hunted alongside wolves and used domestic dogs. This collaboration may have helped modern humans compete with Neanderthals. Other cultures used birds of prey, like eagles and falcons, for hunting through falconry. People have even used cormorants to catch fish. Today, we interact with these animals through ecotourism. People travel to see tiger sharks or big cats in the wild. However, some tour operators provide food to attract predators to specific areas. This practice is controversial because it may change the natural behavior of the animals and their ecosystems.