# Science: An Elementary Teacher’s Guide/Food Chain

Food Chain (food web) is a hierarchical series of organisms each dependent on the next as a source of food. Is the order in which living things eat in the ecosystem. The food chain is the path of food energy from one organism to another in an ecosystem.
* Energy is what is needed to do work or cause change. The source of all energy in a food chain is the sun.
* Sun- the star at the center of our solar system that supplies heat and light to Earth.
Did you know? Food chains were first introduced by the African-Arab scientist and philosopher Al-Jahiz in the 9th century and later popularized in a book published in 1927 by Charles Elton, which also introduced the food web concept
Food Chain Length
The food chain's length is a continuous variable that provides a measure of the passage of energy and an index of ecological structure that increases in value counting progressively through the linkages in a linear fashion from the lowest to the highest trophic (feeding) levels. Food chains are often used in ecological modeling (such as a three species food chain). They are simplified abstractions of real food webs, but complex in their dynamics and mathematical implications.Ecologists have formulated and tested hypotheses regarding the nature of ecological patterns associated with food chain length, such as increasing length increasing with ecosystem size, reduction of energy at each successive level, or the proposition that long food chain lengths are unstable. Food chain studies have an important role in ecotoxicology studies tracing the pathways and bio magnification of environmental contaminants
Producer
Consumer
Decomposer
Example of the Energy Flow in a Food Chain.
* The sun gives energy to the grass
* The grass gives energy to a mouse
* The mouse gives energy to a snake
* A snake gives energy to an eagle
* Dead animals and plants give energy to the earthworms (decomposers)
Producer = plants
Consumer = mice
Decomposer = bacteria
For example, grass produces its own food from sunlight. A rabbit eats the grass. A fox eats the rabbit. When the fox dies, bacteria break down its body, returning it to the soil where it provides nutrients for plants like grass.
Any given species that may eat one type of food or multiple species consumers may feed on similar organism. A barn owl might eat a mouse; A mouse could have been eaten by a sparrow hawk, a snake, or any of the numerous other carnivorous animal.
Plants are the first level in the food chain are known as primary producers. Plants and vegetable make their own food and energy through a process called photosynthesis. Plants make their own food by using sunlight, carbon dioxide from the air, and water from the soil and converting it in the form of sugar. There are three levels of consumers primary consumers organisms that eat plants are the plant eaters of the chain Secondary consumers eat the primary consumers. A mouse might be a primary consumer and a cat might be the secondary there is a third level of consumer called the tertiary consumer these are consumers that eat the secondary and primary consumers. A tertiary consumer could be a wolf that eats the cat and the mouse.
Decomposers break down nutrients in the dead stuff and return it to the soil. The producers can then use the nutrients and elements once it's in the soil. The decomposers complete the system returning essential molecules to the producers.