Tuesday, 16 October 2012

Learn all about Food Chain

Every organism needs to obtain energy in order to live. For example, plants get energy from the sun, some animals eat plants, and some animals eat other animals.
A food chain is the sequence of who eats whom in a biological community (an ecosystem) to obtain nutrition. A food chain starts with the primary energy source, usually the sun or boiling-hot deep sea vents. The next link in the chain is an organism that make its own food from the primary energy source -- an example is photosynthetic plants that make their own food from sunlight (using a process called photosynthesis) and chemosynthetic bacteria that make their food energy from chemicals in hydrothermal vents. These are called autotrophs or primary producers.
Next come organisms that eat the autotrophs; these organisms are called herbivores or primary consumers -- an example is a rabbit that eats grass.
The next link in the chain is animals that eat herbivores - these are called secondary consumers -- an example is a snake that eat rabbits.
In turn, these animals are eaten by larger predators -- an example is an owl that eats snakes.
The tertiary consumers are are eaten by quaternary consumers -- an example is a hawk that eats owls. Each food chain end with a top predator, and animal with no natural enemies (like an alligator, hawk, or polar bear).
The arrows in a food chain show the flow of energy, from the sun or hydrothermal vent to a top predator. As the energy flows from organism to organism, energy is lost at each step. A network of many food chains is called a food web.

Trophic Levels:
The trophic level of an organism is the position it holds in a food chain.
  1. Primary producers (organisms that make their own food from sunlight and/or chemical energy from deep sea vents) are the base of every food chain - these organisms are called autotrophs.
  2. Primary consumers are animals that eat primary producers; they are also called herbivores (plant-eaters).
  3. Secondary consumers eat primary consumers. They are carnivores (meat-eaters) and omnivores (animals that eat both animals and plants).
  4. Tertiary consumers eat secondary consumers.
  5. Quaternary consumers eat tertiary consumers.
  6. Food chains "end" with top predators, animals that have little or no natural enemies.