Temperature

Temperature is the single most ecologically relevant environmental factor. Average land temperature ranges from sub-zero levels at the poles and at high altitudes, up to around 50 degrees C in tropical deserts during summer, and it also varies seasonally, decreasing progressively from the equator towards the poles and from the plains up to mountain tops. Some unique habitats sit at extremes well outside this range -- hot springs run at roughly 80 to 100 degrees C, and deep-sea hydrothermal vents run at average temperatures of around 400 degrees C. Ambient temperature matters ecologically because it directly affects the kinetics of an organism's enzymes, and therefore its entire metabolism, activity level and physiology. Only a small number of species can tolerate and thrive across a wide range of temperatures -- thes …