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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 ...
An apex predator, also known as a top predator or superpredator, is a predator [a] at the top of a food chain, without natural predators of its own. [ 6 ] [ 7 ] Apex predators are usually defined in terms of trophic dynamics , meaning that they occupy the highest trophic levels .
A pyramid of energy or pyramid of productivity shows the production or turnover (the rate at which energy or mass is transferred from one trophic level to the next) of biomass at each trophic level. Instead of showing a single snapshot in time, productivity pyramids show the flow of energy through the food chain. Typical units are grams per ...
In real-world ecosystems, there is more than one food chain for most organisms, since most organisms eat more than one kind of food or are eaten by more than one type of predator. A diagram that sets out the intricate network of intersecting and overlapping food chains for an ecosystem is called its food web. [6]
Food chain length is another way of describing food webs as a measure of the number of species encountered as energy or nutrients move from the plants to top predators. [ 41 ] : 269 There are different ways of calculating food chain length depending on what parameters of the food web dynamic are being considered: connectance, energy, or ...
A food web model is a network of food chains. Each food chain starts with a primary producer or autotroph, an organism, such as an alga or a plant, which is able to manufacture its own food. Next in the chain is an organism that feeds on the primary producer, and the chain continues in this way as a string of successive predators.
At the top of this food chain are apex predators such as lions. [130] Many predators however eat from multiple levels of the food chain; a carnivore may eat both secondary and tertiary consumers. [131] This means that many predators must contend with intraguild predation, where other predators kill and eat them.
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]