by Elizabeth Pennisi
Many carnivorous plants snag prey by luring them onto sticky surfaces from which there is no escape. But a common sundew (Drosera glanduligera) from southern Australia packs a one-two punch. The edges of its spoon-shaped leaves are ringed with up to 18 6-millimeter-long "tentacles" that can move four times faster than the blink of an eye; when an ant or other small insect touches a tentacle, it flicks the unsuspecting insect into the center of the leaf. There, another set of tentacles covered with glue draws the ant deep into the fold of the leaf where it is digested, researchers report today online in PLoS ONE. Just one researcher had observed this catapulting motion in the wild, and only now has it been demonstrated in the lab. The team raised sundews in a greenhouse, feeding the young plants fish flakes and, once the plants got big enough, dead fruit flies. When the plants were mature, the researchers filmed the plant's reactions to live insect visitors. They also tripped isolated tentacles with nylon thread while filming them under a microscope to see close-up how they worked. When activated, the tentacle bends at a hinge near its base; in as few as 75 milliseconds (an eye blink takes about 350 milliseconds) it catapults toward the leaf's center. It's not clear what drives this motion, but once flung, the tentacle can't unwind and be used again, the researchers report. Fortunately, sundews produce new leaves every few days, so there's always a fresh set of traps for unsuspecting prey.
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