Desiccation

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Desiccation is the state of extreme dryness, or the process of extreme drying.

A desiccant is a hygroscopic (water-attracting) substance that causes desiccation in a moderately sealed container.

Biology[change | edit source]

Desiccation tolerance refers to the ability of an organism to withstand or endure extreme dryness, or drought-like conditions.

Plants and animals living in arid or periodically arid environments such as temporary streams or ponds may face desiccation, therefore physiological or behavioural adaptations are necessary to ensure survival. In particular, insects occupy a wide range of ecologically diverse niches and so have a variety of strategies to avoid desiccation.

Desiccation resistance in insects is generally measured by the change in mass during dry conditions.[1] The overall mass difference between measurements before and after aridity exposure is attributed to body water loss.

Extreme cases[change | edit source]

Cryptobiosis refers to the state of an organism that has no detectable metabolic activity, resulting from extreme and unfavorable environmental conditions.
Anhydrobiosis refers to the state of surviving the loss of (almost) all body water.

Tardigrades[change | edit source]

Tardigrades are able to live in environments that would kill most animals.[2] In 2007, scientists discovered that some tardigrades were able to survive 10 days in outer space.[3][4] Tardigrades can survive more than ten years without water.[5]

Rotifers[change | edit source]

Rotifers are specialists at living in habitats where water dries up regularly.

The Monogononta, which have males, produce fertilised 'resting eggs' which can resist desiccation (drought) for long periods.[6]

The Bdelloids, who have no males, contract into an inert form and lose almost all body water, a process known as cryptobiosis. Bdelloids can also survive the dry state for long periods: the longest well-documented dormancy is nine years. After they have dried, they may be revived by adding water.[7]

References[change | edit source]

  1. Chown S.L. & Nicolson S.W. (2004). "Insect physiological ecology". New York: Oxford University Press.
  2. Neuman, Yair (October 2006). "Cryptobiosis: A new theoretical perspective". Progress in Biophysics and Molecular Biology (Elsevier) 92 (2).
  3. Jönsson, K. Ingema; Rabbow, Elke; Schill, Ralph O.; Harms-Ringdahl, Mats; Rettberg, Petra (9 September 2008). "Tardigrades survive exposure to space in low Earth orbit". Current Biology (Elsevier Ltd) 18 (17). ISSN R729-R731. http://www.cell.com/current-biology/abstract/S0960-9822%2808%2900805-1. Retrieved 1 January 2011.
  4. Whalen, Joann K.; Sampedro, Luis (2010). Soil Ecology and Management (illustrated ed.). CABI. pp. 73. ISBN 1845935632.
  5. Grimaldi, David A.; Engel, Michael S. (2005). Michael S. Engel. ed. Evolution of the insects. Cambridge Evolution Series (illustrated, reprint ed.). Cambridge University Press. pp. 97. ISBN 0521821495.
  6. Örstan A. 1995. Desiccation survival of the eggs of the rotifer Adineta vaga (Davis 1873). Hydrobiologia 313/314:373-375
  7. Kirk, Kevin L. et al. 1999. Physiological responses to variable environments: storage and respiration in starving rotifers. Freshwater Biology 42 637-644.