Vessels Resist Bubble Formation

a 100x magnification of a cross section of tilia shows varying shapes and patterns of cells with a green-blue dye

Biological Strategy

AskNature Team

Image: Berkshire Community College Bioscience Image Library / Flickr / Public Domain - No restrictions

Distribute Liquids

Liquids include water, as well as body fluids such as blood, gastric juices, nutrient-laden liquids, and more. To survive, many living systems must move such liquids within themselves or between locations. Because of their properties, liquids tend to disperse unless they are confined in some way. To address this, living systems have strategies to confine fluids for transport, and to overcome barriers such as gravity, friction, and other forces. Some of these same barriers also provide opportunities. Trees and giraffes face the same challenge: how to move fluids (water and blood, respectively) upward against gravity. But their strategies are quite different. The tree moves water using capillary action and evaporation, possibly due to water’s properties of polarity and adhesion. The giraffe’s tight skin provides pressure to assist in blood circulation. and keep blood from pooling in the legs.

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Protect From Gases

Gases are part of most living systems’ environments, especially those exposed to the earth’s atmosphere. Two gases that can act as threats to living systems are oxygen and carbon dioxide; both, paradoxically, are also necessary to life. Thus, living systems must obtain a balance in gas concentrations, selectively protecting from too much gas in some situations and not enough in others. For example, mound-building termites protect themselves by building ventilation shafts to remove excess carbon dioxide from their fungal gardens.

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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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Xylem vessels running up tree trunks prevent gas bubble formation because all surfaces are hydrophilic.

“The water columns in the xylem vessels running up the trunk of a tree provide a dramatic example of what’s possible when all surfaces are hydrophilic. With megapascals of negative pressures virtually any dissolved gas ensures supersaturation, yet bubbles rarely form. It’s a good thing, too- a tiny bubble would rupture a water column since any bubble is itself an appropriate surface for gas formation; and, once formed, bubbles grow almost explosively in a supersaturated liquid.” (Vogel 2003:111)