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Desert Diary


The surface area of a solid object is the total area of all of its exposed surfaces. Schools teach formulas for cubes and cones, cylinders and spheres, pyramids and prisms, but how is surface area important to life in the desert?

Consider a snake. Its long, narrow body has a large surface area for its body volume. This allows a snake to cool down or warm up faster, which is important for cold-blooded creatures! So snakes control their body temperature by controlling their exposed surface area—when they coil or stretch out.

To make another point, consider a cactus! A rounded body shape holds more water volume with less exposed surface area. Less surface area means less exposure to the sun and drying winds. A cactus' upright candle shape has very little surface area exposed when the sun is strongest, directly overhead. The spines themselves have maximum surface area, which maximizes their ability to collect water from the wet winter mists that pass through.

So plants and animals survive in the desert thanks to surface area, and this only scratches the surface!

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Contributor: Lawrence M. Lesser, Mathematical Sciences, 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.