Biomass The total mass of organisms in a given area or volume.

Food Chain A hierarchical (arranged in order of rank) series of organisms each dependent on the next as a source of food.

Food Web A system of interlocking and interdependent food chains.

Trophic Level Each of several hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy.

Autotrophic An organism that manufactures its own food from inorganic substances, such as carbon dioxide and ammonia. Most autotrophs, such as green plants, certain algae, and photosynthetic bacteria, use light for energy (from the sun).

Heterotrophic An organism that cannot manufacture its own food and instead obtains its food and energy by taking in organic substances, usually plant or animal matter.

Producer An organism, as a plant, that is able to produce its own food from inorganic substances.

consumers An organism, usually an animal, that feeds on plants or other animals.

Herbivores An animal that feeds on grass and other plants

Carnivores Any other animal or any plant that feeds on animals.

Omnivores An organism that eats both plants and animals.

Decomposer An organism, usually a bacterium or fungus, that breaks down the cells of dead plants and animals into simpler substances.

Detritivores An organism that feeds on and breaks down dead plant or animal matter, returning essential nutrients to the ecosystem. (Another name for a Decomposer)

Interdependence is mutual dependence between organisms.

Energy transfer The conversion of one form of energy into another, or the movement of energy from one organism to another.

10% Rule When energy is passed in an ecosystem from one trophic level to the next, only ten percent of the energy will be passed on.

First tropic level (T1): Producer Plants (Autotroph)

Second tropic level (T2): primary or first order consumers Plant- eating animal (herbivore or heterotroph)

Third tropic level (T3): secondary consumer An animal that eats a primary consumer (heterotroph ; some are omnivores ; some are carnivores)

Fourth tropic level (T4): Tertiary consumer A carnivore at the topmost level in a food chain that feeds on other carnivores (only eats secondary consumers). (Also known as heterotroph)