Flexible Walls Allow for Ultra-fast Passive Suction

close up of a yellow flower with a blurry dark background

Biological Strategy

Swollen bladderwort

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Capture, Absorb, or Filter Organisms

Many living systems must secure organisms for food. But just as one living system must capture its prey to survive, its prey must escape to survive. This results in capture and avoidance strategies that include trickery, speed, poisons, constructed traps, and more. For example, a carnivorous plant called the pitcher plant has leaves formed into a tube that collect water. Long, slippery hairs within the tube face downward. When insects enter the tube seeking nectar, they lose their footing and slide inside, unable to climb out and escape being eaten and digested by the plant.

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Capture, Absorb, or Filter Liquids

The most common liquid used by living systems is water, which they require to survive. But there are many other liquids that provide nourishment, play a role in defense mechanisms, or serve other purposes. Water varies in its availability; it is sometimes plentiful and sometimes very scarce or only available as fog or mist. To minimize the energy required to capture, absorb, or filter liquids, living systems have strategies that take advantage of the unique properties of the given liquid. For example, water moves from a gaseous to liquid state when it encounters a surface colder than the air. Plants in forests that experience fog and clouds more than rain have strategies that condense liquid water from moist air.

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Store Energy

Once a living system captures energy or transforms one energy form into another, it must frequently save that energy for future use. But energy is difficult to store in some forms. So living systems need strategies to either use energy quickly, or to convert it from forms that are difficult to store (such as electrical or kinetic) to more storable forms. For example, grasshoppers store energy as potential energy in an elastic material in their tendons. When they need to jump, that energy converts into kinetic energy, providing the force needed to escape predators.

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Flowering Plants

Clade Angiosperms (“receptacle seed”): Dandelions, oaks, grasses, cacti, apples

With 416 families containing some 300,000 known species, angiosperms are the most diverse group of plants, and they can be found around the globe in a wide variety of habitats. They are characterized by seeds that grow enclosed in ovaries, which are enclosed in flowers. The floral organs then develop into fruits of myriad kinds and dimensions, from simple seed casings on maples to elaborate fleshy growths like papayas. The oldest flower known from fossils, Montsechia vidalii, appeared during the Jurassic Period 130 million years ago. They are the primary food source for herbivorous animals, which in turn makes them the indirect food source for carnivores as well.

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Flexible trap walls of the bladderwort allow for ultra-fast passive suction by relying on the release of stored elastic energy.

“Carnivorous aquatic Utricularia species catch small prey animals using millimetre-sized underwater suction traps…Suction takes place after mechanical triggering and is owing to a release of stored elastic energy in the trap body accompanied by a very fast opening and closing of a trapdoor, which otherwise closes the trap entrance watertight…We found that this unique trapping mechanism conducts suction in less than a millisecond and therefore ranks among the fastest plant movements known. Fluid acceleration reaches very high values, leaving little chance for prey animals to escape. We discovered that the door deformation is morphologically predetermined, and actually performs a buckling/unbuckling process, including a complete trapdoor curvature inversion. This process…is highly reproducible: the traps are autonomously repetitive as they fire spontaneously after 5–20 h and reset actively to their ready-to-catch condition.” (Vincent et al. 2011: 2909)

“The lenticular Utricularia trap…works with a two-phase mechanism. During the first slow phase…internal glands actively pump water out of the trap interior, so that elastic energy is stored in the trap body owing to a lower internal hydrostatic pressure…A flexible door with protruding trigger hairs closes the entrance watertight. Prey animals can stimulate these hairs and thereby launch the second, ultra-fast phase, which runs passively because of a mechanical conversion of elastic energy into kinetic energy. The triggering results in door opening, trap wall relaxation and water (and thereby prey) influx due to the sudden increase of the trap volume (figure 1c). After the door is closed, the prey is dissolved by digestive enzymes secreted by quadrifid glands, and nutrients are absorbed by the plant. Both phases together form a repeatable ‘active slow deflation–passive fast suction’ sequence.” (Vincent et al. 2011:2909)

Last Updated August 18, 2016

References

Journal article

Ultra-fast underwater suction traps

Proceedings of the Royal Society B: Biological Sciences | 16/02/2011 | O. Vincent, C. Weisskopf, S. Poppinga, T. Masselter, T. Speck, M. Joyeux, C. Quilliet, P. Marmottant

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