Predator in Ecosystems: Definition & Explanation

Instructor: Jeffrey Sack

Jeff is a Biology teacher and has a Doctorate in Educational Leadership

This lesson will define what predators are, explain how they behave, and discuss their role in an ecosystem. Examples of predators will also be given.

What is a Predator?

When you hear the term, 'predator,' the first thing you might think of is the 1987 movie starring Arnold Schwarzenegger. While the premise of this film was purely science fiction, the alien in the movie did fulfill the characteristics of what a predator is - something that hunts its prey. In the wild, predators are those animals that hunt down, kill, and eat other animals. The food a predator hunts is called its prey.

Types of Predators

Large Predators

Predators come in all shapes and sizes. They all have special adaptations that allow them to hunt and kill their prey, with minimal damage to themselves. The most common traits a predator has include very large teeth, sharp claws, and great strength. Many of them are also known to have very bad attitudes (meaning they can be very aggressive) and can cause harm to people. Polar bears, killer whales, and great white sharks all fall into this category. All these animals are much larger than people and have the necessary 'weapons' for killing. Also, there aren't too many people who would want to be trapped in a room with any of them.

The polar bear is considered the largest land carnivore. It can stand over nine feet (3 m) tall on its back legs, and it eats nothing but meat, usually seals. It has very large paws, each tipped with strong claws.

Killer whales can reach a length of 30 (9.5m) feet and weigh up to six tons (5,443 kg). Each of their teeth can be four inches (10 cm) long. They eat seals, sea lions, and fish.

Great white sharks (Figure 1) are the ultimate ocean predator. They are built for nothing more than eating. They are usually 15 feet (4.6 m) feet long, weigh 5,000 pounds (2,268 kg), and have thousands of teeth. There are not too many animals on Earth that put fear into people so well as a great white shark.

Figure 1. Great White Shark
Great White Shark

Smaller Predators

Not all predators, however, are such animals of 'mass destruction.' For example, sea stars (Figure 2) living on the bottom of the ocean are predators. They have neither teeth nor sharp claws, and certainly do not cause fear in humans. Yet, sea stars are considered one of the most dangerous animals to certain types of shellfish. When on the hunt, sea stars use their tube feet to crawl across the ocean floor. When they find a clam, they will grab onto its shell from both sides using their arms. They then begin to pull as hard as they can to try to separate the valves of the shell. The clam is using all of its strength to hold the valves together, but the sea star is stronger. Once the clam tires, and the valves open just a little, the sea star throws up its stomach through its mouth and into the clam. The digestive enzymes in the sea star's stomach digest the clam from the outside.

Figure 2. Sea Star on Ocean Floor
Sea star


Another predator that does not fit the usual profile is the ladybug (Figure 3). This little insect grows to be no more than 0.4 inches (1 cm) long and weighs less than the average paper clip. However, they are known to be voracious predators, often consuming plant-eating insects called aphids. Farmers love them, because they help protect their crops. When ladybugs are first born, the larvae start eating right away. By the time their life is over, a ladybug may have eaten over 5,000 aphids.

Figure 3. Ladybug

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