All living things require water, nutrients, air, sunlight and a proper temperature in order to live. The amount of each that is required and how each is acquired varies depending on the organism.
Sunlight is the key ingredient to all energy on Earth. The sun produces heat and light which are used by every living thing on Earth.
In addition to sunlight, the most important elements for survival among all organisms are nutrients, water and air. Nutrients are required for an organism to grow and sustain itself. Without nutrients an organism begins to break down and eventually dies.
Water is consumed or inhabited by living organisms of all kinds. In animals, water is used to hydrate the body, aid in the digestion of food, and produce necessary fluids such as blood and saliva. Fish and reptiles also receive nutrients from the waters they live in. Plants use water as part of photosynthesis as well as to transport nutrients from the roots to the stalk and flowers.
Air is an essential ingredient for life to both plants and animals. Plants require the carbon dioxide found in the air to complete the process of photosynthesis. When plants go through photosynthesis, they produce oxygen. Land-dwelling animals require the oxygen in the air for respiration, while sea-dwelling animals receive oxygen through the water.