In general, carnivorous plants and the Venus's Flytrap capture our attention: they reverse conventional ideas about who eats whom.
Charles Darwin himself was fascinated by these plants and did experiments to prove that prey trigger rapid plant movements via nerve-like signals and gain nutrients by secreting digestive enzymes.
Darwin further hypothesized that the snap-trap we see in Venus's Flytrap evolved from sticky traps in a sundew-like ancestor. A few years ago, using modern molecular methods, UW Botany Professor Ken Cameron proved Darwin right: fly-traps indeed evolved from sundew relatives.
Now, UW Botany Professor Don Waller and colleague Tom Gibson have taken the story a step further in a paper published in a special issue of New Phytologist commemorating the Darwin bicentennial.
Waller and Gibson explored the relative success of sticky- and snap-traps in capturing smaller and larger prey in bogs dotting the Southeastern U.S. coastal plain. Fly-paper traps like those in sundews efficiently capture tiny insects but larger insects regularly escape. In contrast, snap-traps quickly capture and efficiently digest larger insects but let smaller ones escape.
They concluded that the greater rewards associated with larger insects drove the evolution of snap-traps. Despite this advantage, snap-traps only evolved once (about 65 million years ago) suggesting that their complexity and competition with simpler pitfall traps (as in pitcher plants) limited the chances for repeated origins of these remarkable animal-eating structures.
Waller and Gibson's work was also featured online in the BBC Earth News.