Garden Hunters

A fly lands on a bright-red leaf. It walks around, slurping up sweet nectar. Suddenly, the leaf snaps closed. The bug has been caught inside a Venus flytrap!

The Venus flytrap is a carnivorous plant. It eats small animals like insects and spiders. But why does this plant eat bugs?

Plants don’t usually eat animals. They get energy and nutrients through photosynthesis. This process allows plants to make their own food. They do this by using sunlight, water, and carbon dioxide gas that’s found in the air. Plants also use other nutrients from soil to make food. For a long time, scientists thought this was the only way plants survived.

But in 1875, scientist Charles Darwin found plants that had another way to eat. Wetlands and bogs have soil low in nutrients. That’s why some plants in these water-soaked places eat insects instead. “These plants developed new tricks to get nutrients they can’t get from the soil,” says Carl Procko. He’s a plant biologist who studies Venus flytraps at California’s Salk Institute for Biological Studies.

In fact, there are about 800 known species of carnivorous plants. At least one species can be found on every continent except Antarctica. One thing they all have in common is that they’re expert predators.

A Venus flytrap’s leaf is lined with hairs that look like teeth. Inside its leaf are smaller hairs sensitive to touch. Flies land on the leaf and brush against these tiny hairs. The leaf then quickly snaps shut around the insect.

“One of the coolest things about Venus flytraps is that they can sense their environment and respond very quickly,” says Procko. It takes a fraction of a second for it to react and catch its prey. This allows the plant to nab speedy insects like flies.

The flytrap’s outer teeth form a cage around its meal when its leaf closes. It then fills with digestive fluid. Chemicals in the liquid break down the fly’s insides into goo. The plant then absorbs nutrients from the fly’s body. This process takes about one to two weeks. Only the insect’s hard outer skeleton will be leftover. Finally the flytrap opens again, the insect falls out, and the plant waits for its next meal to land.

Other carnivorous plants have a wide range of tricks to catch and eat bugs (see Meat-Eating Plants!). “Nature delivers up a lot of unexpected things,” says Procko.