The Venus flytrap’s trap has several mechanosensitive trigger hairs that propagate action potentials across the trap when bent with a particular force, velocity, and angle. Closure is a two-step process, in which the initial snap is caused by two action potentials (1 and 4). Subsequent contacts with trigger hairs (2) signal the plant to seal the trap and start the digestive process (3). Recent experiments found that the hairs are sensitive enough to respond to ants walking across the trap, but that smaller traps are more sensitive than larger ones (5), giving small prey the opportunity to escape from large traps (6) that might otherwise waste digestive energy on tiny meals.
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Kerry Grens is a senior editor and the news director at The Scientist. Email her at kgrens@the-scientist.com.