Essential Elements: include nitrogen, calcium, and phosphorus. These are elements are captured by plants and circulated through food chains. Much of the open ocean is actually a desert because it lacks these nutrients and cannot support life forms. In places where cold water is upwelling from the ocean depths, some of these nutrients are carried up from the ocean bottom, and provide food for life forms at the surface.
Food: Food provides energy (fuel) and also amino acids and vitamins necessary for life. Animals need both fuel and vitamins. Without them, they do not thrive.
Temperature:.
Life processes are chemical processes. Life processes operate most efficiently within a narrow temperature range. Think of how we put food in the freezer to keep it from spoiling: freezing temperatures stop those processes. Too much heat also kills: fevers of around 108 degrees Fahrenheit kill humans, because the proteins of which we are formed begin to break down at those temperatures. Both plants and animals have ways of protecting themselves from intermittent extremes of temperature, but need to stay within certain temperature ranges in their environments in order to survive.
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Pressure:.
Life forms are adapted to the atmospheric or aquatic pressures at which they live. People die at high altitudes because they cannot extract enough oxygen from the air. Life forms brought up from the deep ocean will explode as the gasses dissolved in their tissues expand.
Radiation:.
We don't have radiation deserts on earth (yet), but we know that living things need protection from ultra-violet radiation (protection currently provided by the ozone layer), radioactive radiation (high around Chernobyl), and gamma radiation out in space. .
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The food web in the hot desert biome is a simple one. Life in this hot, dry environment is challenging, requiring adaptations from both animals and plants. The soil is often dry, and desert winds carry fine dust particles away, leaving a stony landscape.