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The trophic level of an organism is the number of steps it is from the start of the chain. A food web starts at trophic level 1 with primary producers such as plants, can move to herbivores at level 2, carnivores at level 3 or higher, and typically finish with apex predators at level 4 or 5. The path along the chain can form either a one-way ...
A pyramid of biomass shows the relationship between biomass and trophic level by quantifying the biomass present at each trophic level of an ecological community at a particular time. It is a graphical representation of biomass (total amount of living or organic matter in an ecosystem) present in unit area in different trophic levels.
In the simplest scheme, the first trophic level (level 1) is plants, then herbivores (level 2), and then carnivores (level 3). The trophic level equals one more than the chain length, which is the number of links connecting to the base. The base of the food chain (primary producers or detritivores) is set at zero.
Food chain models typically predict that communities are controlled by predators at the top and plants (autotrophs or producers) at the bottom. [7] Trophic pyramids (also called ecological pyramids) model trophic levels in a food chain and/or biomass productivity. Thus, the foundation of the food chain typically consists of primary producers.
Within an ecological food chain, consumers are categorized into primary consumers, secondary consumers, and tertiary consumers. [3] Primary consumers are herbivores, feeding on plants or algae. Caterpillars, insects, grasshoppers, termites and hummingbirds are all examples of primary consumers because they only eat autotrophs (plants).
In order to more efficiently show the quantity of organisms at each trophic level, these food chains are then organized into trophic pyramids. [1] The arrows in the food chain show that the energy flow is unidirectional, with the head of an arrow indicating the direction of energy flow; energy is lost as heat at each step along the way. [2] [3]
Additional levels to the trophic scale come when smaller omnivores or carnivores are eaten by larger ones. At the top of the food web is the apex predator, this animal species is not consumed by any other in the community. Herbivores, omnivores and carnivores are all heterotrophs. [8] A basic example of a food chain is; grass → rabbit → fox ...
Trophic coherence: The tendency of species to specialise on particular trophic levels leads to food webs displaying a significant degree of order in their trophic structure, known as trophic coherence, [22] which in turn has important effects on properties such as stability and prevalence of cycles.