Environmental Science 15th Edition by Scott Spoolman,Tyler Miller

Exercise 25

MANY OF THE WORLD'S MOST IMPORTANT ORGANISMS ARE INVISIBLE TO US
They are everywhere. Trillions can be found inside your body, on your body, in a handful of soil, and in a cup of ocean water.
These mostly invisible rulers of the earth are microbes, or microorganisms, catchall terms for many thousands of species of bacteria, protozoa, fungi, and floating phytoplankton. They play key roles in the earth's life-support system. Bacteria in our intestinal tracts break down the food we eat, and microbes in our noses help to prevent harmful bacteria from reaching our lungs. Other microbes help to purify the water we drink by breaking down plant and animal wastes in the water. Bacteria and fungi in the soil decompose organic wastes into nutrients that can be taken up by plants that are then eaten by humans and many other plant eaters. Without these tiny creatures, we would go hungry and be up to our necks in waste matter.
Some microorganisms, particularly phytoplankton in the ocean, provide much of the planet's oxygen, and help to regulate the atmosphere's average temperature by removing some of the carbon dioxide produced when we burn coal, natural gas, and gasoline. Other microbes help us to control diseases that affect plants and to limit populations of insects that attack our food crops. In short, microbes are a vital part of the earth's natural capital.
Critical Thinking
What are two advantages that microbes have over humans for thriving in the world?