<span>All organisms need resources for survival, growth and reproduction; in other words, basic functioning of life. These resources include, food, water, protection from predators, light (or darkness, depending on the species), oxygen (for most of the species), shelter, etc. Most of these are space dependent. For example, even if we, as human beings, need only (say) 1 square feet to stand on, does not mean that's all the space we need.
