Venus Flytraps Know How to Count

Figuring out when to chomp is as easy as one, two, three, four, five

Venus Flytrap
This Venus flytrap is just biding its time to ensure the meal is worth its energy. David Aubrey/CORBIS

There’s something about Venus flytraps that has the power to chill. After all, if carnivorous plants can turn on hapless creatures, what’s to say they couldn’t some day turn on you? Now, reports James Gorman for The New York Times, the plants’ nightmarish quality has been taken to a new level with the revelation that Venus flytraps can count.

That’s the latest conclusion of a group of researchers who fooled the plants into thinking they had captured an insect. In their study, published recently in the journal Current Biology, the researchers show that when the tiny hairs that cause the plants’ trap-like jaws to close are stimulated, they cause electrical pulses within the plants. The plant then detects, or rather counts, the number of electrical pulses and uses the information to figure out when to close the trap and how much digestive enzymes it should secrete to dissolve its prey.

Gorman notes that the plants’ traps are a kind of hybrid of jaw and stomach. They’re triggered by the hairs that surround the trap and give the plant its freakily forbidding appearance. But the jaws of the plant don’t close the moment the hairs are triggered. Rather, the researchers found that the jaws seem to only snap shut when the trigger hairs have been stimulated twice within a 20-second window.

The counting isn’t evidence of the plant’s math abilities. These plants usually live in nutrient-poor environments, so the counting shows a kind of plant-based cost-benefit analysis. The plant counts the number of pulses to figure out whether it’s worthwhile to use the energy needed to chomp its food and digest it.

When the plant snaps down on its prey, the movement of the escaping animal triggers the hairs again and again. That’s where the counting kicks into high gear. “After five triggers, glands on the inner surface of the trap also produce digestive enzymes and transporters to take up nutrients,” researchers write in a release about the study. “This input also allows the plant to scale its production of costly ingredients to the size of the meal.”

Venus flytraps are one of just two types of plants that actively capture their prey, but they’re not the only non-human organism that can count. Are they alone in the plant world? It’s not yet certain. But you might not want to stay alone with one now that you know they’re counting along with every bump of their hairy jaws.

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