By John Upton
When animals evolved from plants, well over a billion years ago, they flourished by feasting on their vegetative cousins. Then some plants growing in nutrient-poor soil turned that trick back around on animals: Carnivorous plants evolved and began to feast on some of the animals that feasted on plants.
Perhaps the most famous carnivorous plant is the Venus fly trap. The snapping ‘mouth’ of this plant puts it in ecologists’ ‘active’ trap category. Pitcher plants, by comparison, use ‘passive’ traps – an insect tumbles into a sticky vase-like leaf and is digested.
Sundews are one of the largest groups of carnivorous plants, relying on passive traps to capture their prey. But German scientists studied unusual specimens native to southern Australia and reported that they use active tentacles to catapult passing insects into their otherwise passive traps.
“Prey animals walking near the edge of the sundew trigger a touch-sensitive snap-tentacle, which swiftly catapults them onto adjacent sticky glue-tentacles,” the researchers, from University of Freiburg, reported in the online journal PLoS ONE. “The insects are then slowly drawn within the concave trap leaf by sticky tentacles.”