Things we grew up with seem natural just because we grew up with them. We don't question because questions don't come up—when you're young, everything is just the way things are. Yet, if you stop to think about it, isn't it strange that fish can live underwater? Why, that'd kill us in almost no time at all!
Fish do breathe, of course, but very differently than we do. We absorb oxygen through our lungs, and our lungs are internal, partly for physical protection, but mostly to keep them moist in our dry terrestrial habitat—a necessity for exchange of gases. A fish, surrounded by moisture, merely has to absorb the oxygen that's dissolved in the water. That's fine when there's plenty of dissolved oxygen, but dump sewage or decaying plant or animal material in our Rio Grande, and our fish are in trouble. Many of the decay bacteria need oxygen too, and too much decaying organic material has suffocated many a fish. Faster, but perhaps no more deadly than the pollutants we continue to pour into our air.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
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.
