Hydration Increases Internal Pressure

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Biological Strategy

Legumes

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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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Transform Mechanical Energy

Mechanical energy is made up of kinetic energy (the energy of an object in motion) and potential energy (stored energy). Organisms use mechanical energy in a variety of ways, including capturing prey, transporting seeds, and moving around.

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Modify Pressure

For many living systems, modifying pressure provides extra strength. For others, it provides ways to move air. To use pressure effectively requires a reliable source of pressure, as well as mechanisms to create and release the pressure as needed. Often, modifications in pressure within a living system are created by water, although air can also be a source. An example of a water-facilitated pressure system is wilted leaves that use hydrostatic pressure to stiffen. They do so by bringing solutes (such as salts) into their cells, which causes them to draw in water.

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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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The seeds of legumes can generate tremendous internal pressures by absorbing large amounts of water.

“If you take some dry legume seeds and immerse them in water they swell up. If they’re put in a closed chamber into which water can pass but out of which they can’t squeeze or ooze, then their swelling will push outward on the chamber with surprising force…The affinity of many polysaccharides and proteins for water is extreme–the resulting pressures may reach thousands of atmospheres. (Salisbury and Ross [1969] give references to experiments and calculations.) Wetting of a small quantity of dry seeds accidentally left underneath can lead to the fracture of concrete pavement.” (Vogel 2003:443-444)

Vogel S. Comparative Biomechanics: Life’s Physical World. Princeton: Princeton University Press; 2003. 580 p.

Last Updated August 18, 2016

References

Book

Comparative Biomechanics: Life's Physical World, Second Edition

Princeton University Press | 17/06/2013 | Steven Vogel

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