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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 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]
Food chain in a Swedish lake. Osprey feed on northern pike, which in turn feed on perch which eat bleak which eat crustaceans.. A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as earthworms and woodlice ...
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 flow or a part of a wider food "web".
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.
In above ground food webs, energy moves from producers (plants) to primary consumers and then to secondary consumers (predators). The phrase, trophic level, refers to the different levels or steps in the energy pathway. In other words, the producers, consumers, and decomposers are the main trophic levels.
Biomagnification is a process causing the concentration of a substance (crosses) to increase at higher levels of the food chain. In this scenario, a pond has been contaminated with toxic waste. Further up the food chain, the concentration of the contaminant increases, sometimes resulting in the top consumer dying.
This reduces the length of the food chain and the corresponding trophic energy losses. Costal upwelling zones may have a little as three trophic levels and sustain top-level organisms as large as whales. Conversely, open ocean areas can have as many as six trophic levels and sustain small tuna and squid at the top of the food web. [6]