Sugars Assist Desiccation Tolerance

Biological Strategy

Flat-stemmed clubmoss

AskNature Team

Image: Forest and Kim Starr / Flickr / CC BY - Creative Commons Attribution alone

Protect From Loss of Liquids

Water is essential to life. Liquids, mostly water, make up 70 to 90% of all living systems, and the loss of even a small percentage can mean the difference between life and death. Living systems must maintain a proper liquid balance, which is especially difficult in dry conditions. To do so, they must control the movement of liquids across their boundaries. Living systems do this using structures or waterproof materials to prevent or slow liquid movement. For example, when humans receive a cut, they must limit blood loss. Scattered throughout the bloodstream are lens-shaped structures that serve to plug the wound.

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Protect From Temperature

Many living systems function best within specific temperature ranges. Temperatures higher or lower than that range can negatively impact a living system’s physiological or chemical processes, and damage its exterior or interior. Living systems must manage high or low temperatures using minimal energy, which often requires controlling responses along incremental temperature changes. To do so, living systems use a variety of strategies, such as avoiding high or low temperatures, removing excess heat, and holding heat in. Insulation is a well-known example of managing low temperatures by retaining heat using thick layers of hair, fur, or feathers to hold warm air next to the skin.

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Ferns

Class Polypodiopsida (“many footed appearance”): Ferns, horsetails, whisk ferns

Ferns are a class of plants that reproduce without flowers or seeds, but by spores. With over 10,500 known species, ferns are the second most abundant group of vascular plants after angiosperms (flowering plants). Though they can be found in a variety of habitats, ferns prefer moist, humid environments. Ferns first evolved in the Carboniferous Period about 360 million years ago. Today, ferns are grown for food, medicine, ornamental landscaping, and hold importance in culture and folklore. Several species can also remove pollutants from the atmosphere.

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The tissues of spikemoss survive extremely dry conditions due in part to production of trehalose or sucrose, which behave as water-replacement molecules.

“Desiccation tolerance has been observed in several biological settings other than plant seed maturation. So called ‘resurrection plants’ (Selaginella and Myrothamnus), Tardigrade (Echiniscoides sigimunde), and brine shrimps (Anemia) are all capable of withstanding extended periods of anhydrobiosis. Although in these cases it has been suggested that the sugar trehalose, behaving as a water replacement molecule, is responsible for desiccation tolerance (Clegg 1986; Crowe et al 1987, 1992), it is sucrose which forms the most abundant sugar in higher order plant seeds and which has been postulated to perform the same function in this setting.” (Drew 2006)