When we imagine drama playing out between predators and prey, most of us picture stealthy lions and restless gazelle, or a sharp-taloned hawk latched on to an unlucky squirrel. But Ben Baiser, a post-doctoral fellow at the Harvard Forest and lead author of a new study in Oikos, thinks on a more local scale. His inter-species drama plays out in the humble bogs and fens of eastern North America, home to the carnivorous pitcher plant, Sarracenia purpurea. "It's shocking, the complex world you can find inside one little pitcher plant," says Baiser.
A pitcher plant's work seems simple: their tube-shaped leaves catch and hold rainwater, which drowns the ants, beetles, and flies that stumble in.
But the rainwater inside a pitcher plant is not just a malevolent dunking pool. It also hosts a complex system of aquatic life, including wriggling mosquito, flesh fly, and midge larvae; mites; rotifers; copepods; nematodes; and multicellular algae. These tiny organisms are crucial to the pitcher plant's ability to process food. They create what scientists call a 'processing chain': when a bug drowns in the pitcher's rainwater, midge larvae swim up and shred it to smaller pieces, bacteria eat the shredded pieces, rotifers eat the bacteria, and the pitcher plant absorbs the rotifers' waste.
But that's not the whole story. Fly larvae are also eating the rotifers, midge larvae, and each other, and everybody eats bacteria. It's a complex food web that shifts on the order of seconds.
Aaron Ellison, a co-author on the new study and senior ecologist at the Harvard Forest, says the pitcher plant food web is an ideal model for understanding larger food webswith top predators like wolvesthat change over a longer period of time. He points out, "With pitcher plants, you can hold the whole food web in your hand. The vast number of pitcher plants in one bog provide endless opportunities for detailed experiments on how food webs work, not onl
|Contact: Clarisse Hart|