Aquatic carnivorous plants with ultra-fast traps studied

Feb 16, 2011
Utricularia (here Utricularia vulgaris) are aquatic carnivorous plants equipped with a suction trap for capturing small aquatic animals. Credit Carmen Weißkopf

How do Utricularia, aquatic carnivorous plants commonly found in marshes, manage to capture their preys in less than a millisecond? A team of French physicists from the Laboratoire Interdisciplinaire de Physique has identified the ingenious mechanical process that enables the plant to ensnare any small, a little too curious aquatic animals that venture too closely. It is the reversal of its curvature and the release of the associated elastic energy that make it the fastest known aquatic trap in the world. These results are published on 16 February 2011 on the website of the journal Proceedings of the Royal Society of London B.

Utricularia are that capture small prey with remarkable suction . Utricularia are rootless plants formed of very thin, forked leaves on which wineskin-shaped traps, just a few millimeters in size, are attached. Only the flowers, standing on long stems, stick out of the water. The traps are underwater. When an aquatic animal (water fleas, cyclops, daphnia or small ) touches its sensitive hairs, the trap sucks it in, in a fraction of a second, along with water, which is then drained through its walls.

Longitudinal section of a trap (known as an utricle) of the Utricularia (Utricularia vulgaris) seen here with a scanning electron microscope (SEM). Aquatic carnivorous Utricularia use these suction traps to ensnare aquatic animals. Credit: Carmen Weißkopf

In order to understand the mechanical process involved, the researchers observed and recorded the extremely rapid movements of the capture phase with a . The scientists show that the trap door buckles, which reverses its curvature and allows it to open and close very rapidly, thus entrapping its prey. The suction time (less than a millisecond) is much shorter than was previously assumed.

How exactly does this implacable trap operate mechanically? In the first stage, which lasts several hours, the plant slowly pumps out the liquid it contains, thus placing the trap under negative pressure. During this arming phase, elastic energy is stored in the trap walls. The trap is ready to close on its prey. The slightest touch on a sensitive hair attached to the trap door triggers its opening. This begins with the "buckling" of the trap door, in other words a sudden change in shape. The trap door thus acts like an elastic valve: initially bulging outwards, it turns inwards, reversing its curvature.

The release of the elastic energy stored in the trap walls then create a suction vortex, with accelerations up to 600 g, leaving the prey that has set off the mechanism little chance of escape. Then, very rapidly, the trap door reverses again and returns to its initial shape. The trap is then hermetically closed around its prey, which will be dissolved by the plant's digestive enzymes, providing it with precious nutrients. Until its next capture...

Numerical simulation of the elastic door of the trap during opening. Since the trap is under negative pressure, only a small perturbation is needed to suddenly reverse the curvature of the trap door inwards. This phenomenon, known as buckling instability, occurs in everyday life when a bulging wall (for example a balloon or a plastic bottle) is put under negative pressure. The curvature reversal results in the opening of the trap door, as soon as the free edge is no longer pressing on the threshold (in blue). Credit: Marc Joyeux

These results, observed with a high-speed camera, have also been confirmed by the researchers' numerical simulations, which will be published in a second article in Physical Review E.

Explore further: Research of plain wren duets could help further understand fundamentals of conversation

More information: This work will be published in Proceedings of the Royal Society of London B (Biological sciences), in the press (2011), "Ultra-fast underwater suction traps" O. Vincent, C. et al. The numerical model of the trap will be published in Physical Review E, in the press (2011) "Mechanical model of the ultra-fast underwater trap of Utricularia" by M. Joyeux, et al.

add to favorites email to friend print save as pdf

Related Stories

No such thing as a free lunch for Venus flytraps

Aug 03, 2010

Charles Darwin described the Venus Flytrap as 'one of the most wonderful plants in the world.' It's also one of the fastest as many an unfortunate insect taking a stroll across a leaf has discovered. But what powers this ...

Snaring bigger bugs gave flytraps evolutionary edge

Aug 26, 2009

(PhysOrg.com) -- Carnivorous plants defy our expectations of how plants should behave, with Venus flytraps employing nerve-like reflexes and powerful digestive enzymes to capture and consume fresh meat.

For carnivorous plants, slow but steady wins the race

Sep 14, 2009

Like the man-eating plant in Little Shop of Horrors, carnivorous plants rely on animal prey for sustenance. Fortunately for humans, carnivorous plants found in nature are not dependent on a diet of human blood but rather ...

Anti-adhesive layers leave no hope for insects

Jan 13, 2006

Plants are able, using organic substances, to achieve effects that we otherwise mostly know only from technical materials. One example of this is the carnivorous pitcher plant, as researchers from the Max Planck ...

Recommended for you

A molecular compass for bird navigation

14 hours ago

Each year, the Arctic Tern travels over 40,000 miles, migrating nearly from pole to pole and back again. Other birds make similar (though shorter) journeys in search of warmer climes. How do these birds manage ...

100,000 bird samples online

16 hours ago

The Natural History Museum (NHM) in Oslo has a bird collection of international size. It is now available online.

New genetic technologies offer hope for white rhino

17 hours ago

With support from the Seaver Institute, geneticists at San Diego Zoo Institute for Conservation Research are taking the initial steps in an effort to use cryopreserved cells to bring back the northern white rhino from the ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.