Researchers at The University of Bristol have discovered a new mechanism that carnivorous plants use to cleverly trap their prey.
In case you’re not that into plants and therefore do not know the related terminology, a carnivorous plant is one that obtains their energy source (i.e. their vital nutrients for survival) through ‘trapping’ their prey.
You can probably picture a typical carnivorous plant without realising it. They are usually opened-bodied plants, with vivid, enticing colours, and a retractile lid, similar to the structure of a typical water pitcher. Hence their ‘slang’ name pitcher plants. You may also know the most famous of them all: the Venus flytrap. This particular plant captures its prey through its two lobes snapping shut after double stimulation of just one of the hairs (also known as ‘the trigger hair’) found upon the lobe. Although the precise mechanism is still unclear, it is believed that the stimulation works in a similar manner as the generation of an action potential in our nerves. The theory states that there is a calcium (or ion) build-up, which then propagates across the entire lobe, causing it to rapidly snap shut and cunningly trap whatever is inside. There are also many other types of carnivorous plants with similar mechanisms, including: the snap, pitfall, bladder, combination and, my personal favourite, the lobster-pot.
Until recently, the mechanism behind the action of predation trapping by the plant species Nepenthes gracilis was unknown. It is now clear, however, exactly how this clever plant traps its prey. The mechanistic method is all due to its stiff, rigid lid, and that’s it. Think of it as a diving board – although it is stiff, it still has some good bounce to it. Also like a diving board, the lid of the plant overhangs its trap; ingeniously positioned to catch any and all poor insects that happen to befall this crafty plant. Now here comes the utmost cleverness of this plant: it uses nature; the external gravitational energy of a falling rain drop to cause a spring back motion, the typical motion witnessed just after someone has jumped off a diving board. This uncontained and unexpected force (also known as oscillation) hurtles the insect directly into the plants trap, sealing its fate. They discovered this interesting mechanism through the use of laser vibrations recorded by quick motion sensor video. The research also demonstrated that this rapid movement mechanism is faster than the natural reactions of some animals (e.g. to danger), and is quicker in response than the Venus flytrap.
A new sub-category may need to be created to describe the individuality of this carnivorous plant, as it is neither ‘active’ like the Venus flytrap (meaning it generates energy to capture its prey) nor ‘passive’ like many other pitcher plants. Instead, it generates its own natural, free energy to create rapid movements in order to trap its prey. A very unique and fascinating plant feature indeed.
Devon Smith The University of Sheffield @DevonCaira