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.
ScienceNOW, the daily online news service of the journal Science
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Cape Sundew Plant
By employing a "flypaper trap" through the sticky glands found on its leaves, this cape sundew plant is able to capture two dragonflies. After prey land on the plant, the other tentacles move to further trap the prey. The plant is then able to digest its prey through enzymes also found on the glands. Photo credit: Flickr/josef.stuefer
As insects enter the cobra-like pitcher of the plant, they get trapped after getting tired-out from being unable to find an exit. From there, a community of bacteria (rather than digestive enzymes) break down the captured insects. Photo credit: Flickr/Swamibu
The Venus flytrap is know for it's snap trap mechanism, which is triggered by the tiny hairs found inside the trap. After the trap is closed, it acts as a "stomach," where digestive enzymes are released by the lobes. Photo credit: Flickr/Webbaliah
These plants trap their prey by using their underground root-like tubes. Known as the lobster-pot trap, prey easily enter the tubes, but are unable to exit. From there, the captured prey is moved upward where it is digested. Photo credit: Flick/radmegan
Seychelles Pitcher Plant
First, insects are seduced by its colorful lid. They are then tempted to move inside the pitcher by its nectar-producing glands. The bad news for the prey is that the waxy inner lining of the pitcher causes insects to slip and fall into the acidic, digestive fluid found at the bottom of the pitcher.
Fork-leaved Sundew Plant
This lovely sundew plant attracts its prey through the flypaper trap mechanism. Photo credit: Flickr/kaibara87
As a rootless aquatic plant, the waterwheel is able to trap its prey similarly to the Venus flytrap. Through rapidly closing its traps, it's able to capture small aquatic prey.
Growing in nutrient poor soil, the dewy pine, unlike the sundew, is unable to move its tentacles to further trap prey. However, its sweet aroma, coupled with its sticky glands, attract and trap insects. Photo credit: Flickr/alexlomas
The Purple Pitcher plant is able to attract insects that then fall into its pitcher base and drown in the pooled rainwater. After that, enzymes digest the dead prey. Photo credit: Flickr/Sandy Richard
Found in both terrestrial and aquatic settings, the bladderwort plant traps its prey through a "bladder trap" mechanism. Simply put, after a partial vacuum is formed in the "bladder" of the plant, its able to suck its prey up to be digested. Photo credit: Flickr/Chris_Moody
Pinguicula Mundi (type of Butterworts)
Butterworts use their large, sticky, glandular leaves to trap their prey. However, its pretty flowers are held far from the sticky leaves so that it doesn't end up trapping potential pollinators. Photo credit: Flickr/E-Infantes