Plants can't move very fast; or this has been the common assumption among biologists and common people alike. But now, researchers found a plant that defies all assumptions: it contains long tentacles that snap out, grab an insect and throw it into the plant's digestive system, all within a fraction of a second.
By looking at an Australian plant called the sundew, a research group from the University of Freiburg discovered how this tentacle-catapult system works, in a study that provides deeper insight into how carnivorous plants have evolved, and how plants can learn to adjust to poor environmental conditions. Dr. Thomas Speck and his team used a high-speed camera to record the tentacles of the southern Australia native sundew plant Drosera glanduligera in action. They found that the tentacles can extend outwards toward a passing by insect, and literally fling the insect into the plant's sticky tentacles, which will then digest the prey. The entire catapult action takes less than a tenth of a second, compared to the minutes to hours that sticky bulbs usually take to trap an insect.
The tentacles have no muscle tissue; the entire action appeared to occur by rapidly redistributing water inside each cell to create the whip-like motion. In addition, cells on one side of the tentacle became distorted during the catapulting event, which further enhanced the motion. Once a tentacle had grabbed an insect, it was discarded. Since the south Australian sundew grows very quickly, and has a large number of these tentacles, losing a handful of them does not represent a big problem.
"These catapulting snap tentacles could help increase the reach of a plant's leaf trap beyond the glue tentacles, and capture larger insects," said Dr. Speck.
Meat-eating plants (mostly dining on insects) are of keen interest to biologists. Charles Darwin called them "the most wonderful plants in the world." Aside from morbid curiosity (and the star of the musical "Little Shop of Horrors"), these plants show biologists how adaptations occur in reaction to poor soil, low nutrients, and the effects of agricultural and commercial development. In the case of the Australian sundew, they also are helping blur the line between plants and animals.
For a video, go to http://www.youtube.com/watch?v=Zzi3XDQs-i0
For the research report, go to http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0045735