The ability to count helps Venus flytraps – possibly the most iconic plants that hunt – to be skilful carnivores, according to a new study.
Venus flytrap’s sensitive trigger hairs send signals to the plant whenever bugs move around the plant’s traps. Researchers have now found that Venus flytraps (Dionaea muscipula) are in fact able to count how many times the bugs brush up against the trigger hairs, before they close the tap.
Despite its name, the plant usually consumes spiders, grasshoppers, ants, beetles, and not so much flying insects. In search for food, bugs go on Venus flytrap’s open trap to collect juicy nectar. Electrochemical impulses are sent through the plant as soon as the bug touches one of the trigger hairs, which signals the presence of prey.
To be certain that the prey is indeed present and it is not just a false alarm – like a raindrop – and to sense more movement, the plant waits for about twenty seconds. When the bug brushed against a sensitive trigger hair for the second time, it sets off the snap of the plant’s trap.
When the prey is caught, the Venus flytrap produces jasmonate – a lipid-based hormone signal that gets the plant ready for the digestion process. Jasmonate acts as a touch hormone in non-carnivore plants.
The plants starts releasing digestive enzymes the fifth time the bug touches the sensitive trigger hairs. Researchers said that the enzymes activate the plant’s stomach. Then, each touch to the sensors stimulates the production of more digestive enzymes and jasmonate.
Venus flytrap is a carnivorous plant native to the East Coast of the United States in North Carolina and South Carolina. The plant is carnivorous because it often lives in areas where the soil lacks vital nutrients.
The counting process helps Venus flytrap be more efficient. Based on what it learns about its prey – through the bug’s movements – the hunter plant produces a specific cocktail of digestive enzymes. For instance, a bigger insect will tell the plant to generate more such digestive enzymes.
Rainer Hedrich, lead author of the study and a biophysicist at the Julius Maximilian University of Würzburg in Germany (also referred to as the University of Würzburg), said that the Venus flytrap is thus able to balance the benefit and cost of hunting.
The study was published Thursday (Jan. 21) in the journal Current Biology.
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