National Geographic : 2010 Mar
Trigger hair Tentacle Gel- secreting gland Teeth Nectar- secreting glands Digestive glands to a foot deep and can consume a whole frog or even a rat unlucky enough to fall into them. Sophisticated chemistry helps make the pitcher a death trap. Nepenthes rafflesiana, a pitcher plant that grows in jungles on Borneo, produces nectar that both lures insects and forms a slick surface on which they can't get a grip. Insects that land on the rim of the pitcher hydroplane on the liquid and tumble in. e digestive uid in which they fall has very di erent properties. Rather than being slippery, it's gooey. If a y tries to li its leg up into the air to escape, the uid holds on tenaciously, like a rubber band. Many carnivorous plants have special glands that secrete enzymes powerful enough to pen- etrate the hard exoskeleton of insects so they can absorb nutrients from inside their prey. But the purple pitcher plant, which lives in bogs and infertile sandy soils in much of North America, enlists other organisms to digest its food. It is home to an intricate food web of mosquito lar- vae, midges, protozoans, and bacteria, many of which can survive only in this unique habitat. The animals shred the prey that fall into the pitcher, and the smaller organisms feed on the debris. Finally, the pitcher plant absorbs the nutrients released by the feeding frenzy. "Hav- ing the animals creates a processing chain that speeds up all the reactions," says Nicholas Gotelli of the University of Vermont. "And then the plant dumps oxygen back into the pitcher for the insects. It's a tight feedback loop." by the thousands in the bogs at the Harvard Forest in central Mas- sachusetts. One late spring day Aaron Ellison took me on a tour, stopping from time to time to watch patiently as I pulled a sinking leg out of the muck. "You haven't had a real bog experi- ence till you're up to your crotch in it," said Elli- son, a senior ecologist at the forest. Little orange ags uttered across the bogs. Each one marked a pitcher plant impressed into the service of sci- ence. In the distance a student was feeding ies to the agged plants. e researchers raise these insects on food spiked with unusual forms of carbon and nitrogen so they can later harvest the pitcher plants and measure how much of Sticky Traps Sundew (Drosera) Tentacles sparkling with sticky gel arm more than 180 sundew species. The struggle of stuck prey stimulates other tentacles to bend toward the captive, coating it with enzymes that digest it. Snap Traps Venus flytrap (Dionaea) The trap closes in a tenth of a second when prey hit at least two trigger hairs---or one hair twice. Teeth form a cage to block escape. The trap slowly tightens, releases digestive fluids, then reopens in about ten days.