It鈥檚 as easy as one, two three鈥� Before they really chow down, Venus flytraps count to five.
When an insect wanders on to one of these carnivorous plants, every misstep is tallied and converted into chemical signals. This helps the plant to catch its prey and then work out how to go about digesting it.
We knew that some plants overnight. The new research now shows that the Venus flytrap (Dionaea muscipula) counts external signals in real time, recording the number of times it is touched and translating that information into chemical signals that do different things.
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Brushing just one of the sensitive trigger hairs on a flytrap once isn鈥檛 enough to spring it shut. But if a second touch follows, the . That鈥檚 because the first touch causes molecules to build up in the trap鈥檚 sensory hairs and the second pushes their concentration across a threshold, resulting in an electrical impulse that activates the trap.
This previous finding led of the University of W眉rzburg in Germany and his team to feed crickets to flytraps and test the plants鈥� impulses to investigate what happened next.
From the cricket鈥檚 perspective, it鈥檚 not a pretty picture. 鈥淚f you don鈥檛 panic, the trap will open,鈥� Hedrich says. 鈥淏ut like everybody, once you are trapped you panic, so you will try to escape 鈥� and once you are struggling, you touch the other hairs.鈥�
Touchy subject
After the second touch seals the insect inside, the flytrap starts to make a hormone called jasmonic acid, a chemical the plants release when fed upon by herbivores to trigger defence compounds. Carnivorous plants have 鈥渢urned the sword around鈥� and use jasmonic acid to capture animals, Hedrich says.
With a third touch by the cricket, now from inside the trap, the plant begins to make digestive enzymes. And after five touches, it kicks off digestion in earnest, releasing enzymes and turning on pumps that suck sodium into the plant as its meal turns to liquid.
The number of touches after five 鈥� with the crickets averaging 63 within an hour of capture 鈥� leads to a proportional response. 鈥淚t measures the touches to see what type of visitor it is,鈥� Hedrich says. Bigger insects take longer to subdue, and their struggling summons enough enzymes to do the trick.
At the same time, the plant avoids spending rare nutrients like nitrogen or wasting energy by releasing more digestive juices than it needs to.
It鈥檚 not quite plant arithmetic, but it鈥檚 impressive nonetheless, says of the University of Washington in Seattle. 鈥淭he Venus flytrap is hardwired to respond in the way that鈥檚 now being described,鈥� she says.
at the University of New Hampshire in Durham agrees. 鈥淥bviously it doesn鈥檛 have a brain to go 鈥榦ne, two, three, four鈥�,鈥� he says. 鈥淓ffectively, it鈥檚 counting. It鈥檚 just not thinking about it.鈥�
Journal reference: Current Biology, DOI:
Read more: Intelligent life: Why don鈥檛 we consider plants to be smart?;
Root intelligence: Plants can think, feel and learn
Image credit: Chris Mattison/naturepl.com
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