Animals eat in order to carry out the seven necessary functions:
- Movement
- Respiration
- Growth
- Nutrition
- Excretion
- Sensitivity
- Reproduction.
Living organisms need energy and a diet. Molecules in foodstuffs are absorbed by the body’s most vital organs to increase both red blood cells’ strength - this is where aerobic respiration takes place due to the conversion of energy - and white blood strength to ward off infectious disease. By replacing all the energy lost in life’s processes, muscles remain strong and the water molecules lost in waste can be replaced, especially after exercise or on a hot day. There are several types of food groups which are each useful for particular functions.
Certain vegetables and fruit contain minerals which are produced in the body to enable people to see and taste; carbohydrates from bread are extra sources of energy though too many can bloat one’s stomach; proteins are essential for muscles and sugars and salts also help regulate mineral content.
In some cases, the ecological cycle dictates that some animals eat one another, either due to dominance in the herd or to regulate the numbers, we thus speak of the food cycle or chain. A food chain starts with the primary energy source, usually the sun or deep boiling-hot sea vents, which feeds an organism that makes its own food from the primary energy source. These are called autotrophs or primary producers. Next come organisms that eat the autotrophs; these organisms are called herbivores or primary consumers, which are eaten by secondary consumers, which are eaten by larger predators which are eaten by a top predator with no enemies, such as an alligator or polar bear.
When any organism dies, it is eventually eaten by detrivores (like vultures, worms and crabs) and broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues. In any food web, energy is lost each time one organism eats another. Because of this, there have to be many more plants than there are plant-eaters. Although there is intense competition between animals, there is also an interdependence in order for there to be equilibrium.
