Distantly related organisms often have more in common than we'd think. Take plants and ourselves as an example. As with other terrestrial organisms, special adaptations are necessary to survive in a non-aquatic habitat. Excessive loss of water from the body can result in death. So both plants and animals that live on land have waterproof surfaces to cut down the amount of water lost. But both plants and humans must preserve some surfaces that remain damp at all times. Tissues must be wet for gas diffusion. Plants must acquire carbon dioxide gas from the air to supply the carbon that is the basis for life on earth, and we require oxygen from the air to help burn the carbon-containing substances that we require for energy. Thus the internal surfaces of both leaves and lungs must remain damp, allowing loss of water to the atmosphere by evaporation.
Many of our desert plants do have an advantage here, though—they can
close off entryways to the leaf's interior, while more than a few minutes without
breathing is fatal to us.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.