Killer Plants

Most plants probably seem harmless enough. They just sit, unmoving, soaking up the sun. But don’t be fooled: Some are actually secret killers. They lie in wait for small bugs, fish, and even mammals to fall into their traps. Then—CHOMP—gobble them up!

Worldwide, there are more than 800 species of carnivorous plants—ones that trap and eat animals. They’re found on every continent except Antarctica. Like all plants, they can make their own food using photosynthesis. Their leaves harness the sun’s energy to turn water and carbon dioxide gas into sugar the plants use as food.

So why eat animals? Plants can’t complete photosynthesis without important minerals like nitrogen (N) and phosphorus (P). Most plants use their roots to suck up these nutrients from the soil. But carnivorous plants grow in waterlogged wetlands and swamps where these minerals are scarce. To survive, they’ve developed adaptations so they can feed on other organisms. “It’s a way to get nutrients the soil can’t provide,” says Liane Cochran-Stafira, an ecologist at Saint Xavier University in Illinois. Read about four clever ways carnivorous plants capture their prey.

Most plants probably seem harmless. They just sit in one spot and soak up the sun. But don’t be fooled. Some are secret killers. They wait for small bugs, fish, and even mammals to fall into their traps. Then the plants gobble them up. CHOMP!

More than 800 species of carnivorous plants are found worldwide. These plants trap and eat animals. They live on every continent except Antarctica. Like all plants, they can use photosynthesis to make food. Their leaves take in the sun’s energy. They use it to turn water and carbon dioxide gas into sugar. Then the plants use the sugar as food.

So why eat animals? Plants need important minerals to complete photosynthesis. These include nitrogen (N) and phosphorus (P). Most plants suck up these nutrients from the soil with their roots. But carnivorous plants grow in waterlogged wetlands and swamps. These minerals are in short supply there. To survive, the plants developed adaptations so they can feed on other organisms. “It’s a way to get nutrients the soil can’t provide,” says Liane Cochran-Stafira. She’s an ecologist at Saint Xavier University in Illinois. Carnivorous plants have clever ways to capture prey. Read about four of them.

A Venus flytrap’s leaf looks like a gaping mouth surrounded by spiky teeth. Flies and other insects land on the leaf, attracted by its bright-red color and sweet nectar. But if a bug brushes against the tiny hairs inside the leaf, it snaps shut. “One of the coolest things about Venus flytraps is that they can sense their environment and respond very quickly,” says Carl Procko. He’s a biologist at the Salk Institute for Biological Studies in California.

Once the bug is trapped, the leaf fills with digestive fluids. They break down the bug’s body into a liquid the plant can soak up. The whole process takes about two weeks. Then the leaf reopens—ready to nab its next meal.

Sometimes a falling leaf brushes against the flytrap, tricking it into closing. But it won’t be fooled for long. If the “food” doesn’t move, the trap opens back up.

A Venus flytrap’s leaf looks like a wide mouth with spiky teeth. Its bright-red color and sweet nectar attract flies and other insects. So they land on the leaf. But tiny hairs are inside the leaf. If a bug brushes against them, the leaf snaps shut. “One of the coolest things about Venus flytraps is that they can sense their environment and respond very quickly,” says Carl Procko. He’s a biologist at the Salk Institute for Biological Studies in California.

After the bug is trapped, the leaf fills with digestive fluids. They break down the bug’s body into a liquid. Then the plant absorbs it. The whole process takes about two weeks. Then the leaf reopens. It’s ready to grab its next meal.

Sometimes a falling leaf brushes against the flytrap. That tricks it into closing. But it won’t be fooled for long. If the “food” doesn’t move, the trap opens again.

This sundew plant has caught an azure damselfly in its sticky grip. The plant’s leaves are lined with long, flexible tentacles. The tip of each tentacle oozes nectar mixed with a super-gooey, snot-like substance. It’s hard for an insect to resist landing on the leaf for a sip of the sweet treat. But it will quickly find itself glued in place.

The plant reacts to the struggling insect. It wraps its tentacles around the wriggling prey. Then the entire leaf slowly curls around the helpless victim, smothering it in about 15 minutes. The tips of the sundew’s tentacles also release digestive enzymes. They turn the insect’s body into goo so the plant can extract its nutrients. Sundews eat flies, gnats, and mosquitoes found in the swampy areas where the plants live.

This sundew plant has a sticky grip. It just caught an azure damselfly. The plant’s leaves are lined with long, flexible tentacles. Nectar oozes from the tip of each tentacle. The nectar is mixed with a super-gooey, snot-like substance. An insect lands on the leaf for a sip of this sweet treat. But it quickly becomes glued in place.

The insect struggles, and the plant reacts. It wraps its tentacles around the wriggling prey. Then the entire leaf slowly curls around the helpless victim. It smothers the insect in about 15 minutes. The tips of the sundew’s tentacles also release digestive enzymes. They turn the insect’s body into goo. Then the plant can absorb its nutrients. Sundews eat flies, gnats, and mosquitoes. These insects live in swampy areas with the plants.

Bladderworts are aquatic plants that grow in fresh water all over the world. The plants’ long stems are covered in water-filled pouches, called bladders. Each pouch is about the size of a human fingernail. Bladderworts use these pouches to suck up tiny critters like larvae—immature forms of some insects—and tiny fish.

Bladderworts are aquatic plants. They grow in fresh water around the world. The plants’ long stems are covered in water-filled pouches, called bladders. Each pouch is about the size of a human fingernail. Bladderworts use these pouches to suck up tiny fish and tiny critters like larvae. These are immature forms of some insects.

To set its traps, the plant pumps all the water out of its bladders. Like squeezing the bulb of an eyedropper, this creates suction inside the pouches. When small prey swim by, they disturb tiny hairs that extend from the mouth of each bladder. This triggers the bladders to open. SLURP! Water rushes inside, along with the prey. The bladderwort’s pouches close, trapping the animals inside. The bladders fill with digestive fluids, allowing the plant to consume the snagged snacks.

The plant pumps the water out of its bladders to set its traps. This works like squeezing the bulb of an eyedropper. It creates suction inside the pouches. Tiny hairs extend from the mouth of each bladder. When small prey swim by, they disturb the hairs. This makes the bladders open. SLURP! Water rushes inside, along with the prey. The bladderwort’s pouches close. The animals are trapped inside. The bladders fill with digestive fluids so the plant can consume its catch.

An ant walks along the rim of a pitcher plant. The plant’s pitcher—or bell-shaped leaves—are coated in sweet-smelling nectar that attracted the hungry insect. The pitcher is also extremely slippery. Suddenly, the ant loses its footing and falls inside. The inner walls of the plant’s pitcher are covered in stiff, downward-pointing hairs. This makes it nearly impossible for the doomed ant to climb out.

The insect has fallen into what’s known as a pitfall trap. It’s the most common way carnivorous plants capture prey. The ant quickly drowns in a liquid that fills the pitcher. The liquid contains enzymes. These molecules break down the animal’s soft body parts over several days so the plant can absorb its nutrients.

Some species of large pitcher plants can catch prey the size of tiny mice. There’s even one big enough for certain rodents to sit on. They can eat the plant’s nectar without falling into the trap. The animal repays the plant for the meal by pooping into it, providing it with nutrients (see “Plant Potty,” Science World, December 18, 2023).

An ant walks along the rim of a pitcher plant. The plant’s bell-shaped leaves form the pitcher. They’re coated in sweet-smelling nectar. This attracted the hungry insect. The pitcher is also extremely slippery. Suddenly, the ant slips and falls inside. The inner walls of the plant’s pitcher are covered in stiff hairs. They point downward, so the doomed ant can’t climb out.

The insect has fallen into a pitfall trap. This is the most common way for carnivorous plants to capture prey. The pitcher is full of liquid, and the ant quickly drowns. The liquid contains enzymes. These molecules break down the animal’s soft body parts over several days. Then the plant can absorb its nutrients.

Some species of pitcher plants are larger. They can catch prey the size of tiny mice. One is even big enough for certain rodents to sit on. They can eat the plant’s nectar without falling into the trap. The animal poops into the plant to repay it for the meal. This gives the plant nutrients (see “Plant Potty,” Science World, December 18, 2023).