Food chain

A food chain is a linear network of links in a food web starting from producer organisms (such as grass or trees which use radiation from the Sun to make their food) and ending at apex predator species (like grizzly bears or killer whales), detritivores (like earthworms or woodlice), or decomposer species (such as fungi or bacteria). A food chain also shows how the organisms are related with each other by the food they eat. Each level of a food chain represents a different trophic level. A food chain differs from a food web, because the complex network of different animals' feeding relations are aggregated and the chain only follows a direct, linear pathway of one animal at a time. Natural interconnections between food chains make it a food web. A common metric used to quantify food web trophic structure is food chain length. In its simplest form, the length of a chain is the number of links between a trophic consumer and the base of the web and the mean chain length of an entire web is the arithmetic average of the lengths of all chains in a food web.[1][2]

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.[3][4][5]

Food chain
Food chain in a Swedish lake. Osprey feed on northern pike, which in turn feed on perch which eat bleak that feed on mountain shrimp.

Food chain length

Chesapeake Waterbird Food Web
This food web of waterbirds from Chesapeake Bay is a network of food chains

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.[7]

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.[8]

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.[7] Food chain studies have an important role in ecotoxicology studies tracing the pathways and biomagnification of environmental contaminants.[9]

Producers, such as plants, are organisms that utilize solar or chemical energy to synthesize starch. All food chains must start with a producer. In the deep sea, food chains centered on hydrothermal vents and cold seeps exist in the absence of sunlight. Chemosynthetic bacteria and archaea use hydrogen sulfide and methane from hydrothermal vents and cold seeps as an energy source (just as plants use sunlight) to produce carbohydrates; they form the base of the food chain. Consumers are organisms that eat other organisms. All organisms in a food chain, except the first organism, are consumers.

In a food chain, there is also reliable energy transfer through each stage. However, all the energy at one stage of the chain is not absorbed by the organism at the next stage. The amount of energy from one stage to another decreases.[10]

See also


  1. ^ Briand, F.; Cohen, J. E. (1987). "Environmental correlates of food chain length" (PDF). Science. 238 (4829): 956–960. doi:10.1126/science.3672136. Archived from the original (PDF) on 2012-04-25.
  2. ^ Post, D. M.; Pace, M. L.; Haristis, A. M. (2006). "Parasites dominate food web links". Proceedings of the National Academy of Sciences. 103 (30): 11211–11216. doi:10.1073/pnas.0604755103. PMC 1544067.
  3. ^ Elton, C. S. (1927). Animal Ecology. London, UK.: Sidgwick and Jackson. ISBN 0-226-20639-4.
  4. ^ Allesina, S.; Alonso, D.; Pascal, M. "A general model for food web structure" (PDF). Science. 320 (5876): 658–661. doi:10.1126/science.1156269. Archived from the original (PDF) on 2016-05-15.
  5. ^ Egerton, F. N. (2007). "Understanding food chains and food webs, 1700-1970". Bulletin of the Ecological Society of America. 88: 50–69. doi:10.1890/0012-9623(2007)88[50:UFCAFW]2.0.CO;2.
  6. ^ Martinez, N. D. (1991). "Artifacts or attributes? Effects of resolution on the Little Rock Lake food web" (PDF). Ecological Monographs. 61 (4): 367–392. doi:10.2307/2937047.
  7. ^ a b Vander Zanden, M. J.; B. J., Shuter; Lester, N.; Rasmussen, J. B. (1999). "Patterns of food chain length in lakes: A stable isotope study" (PDF). The American Naturalist. 154 (4): 406–416. doi:10.1086/303250. PMID 10523487.
  8. ^ Post, D. M.; Conners, M. E.; Goldberg, D. S. (2000). "Prey preference by a top predator and the stability of linked food chains" (PDF). Ecology. 81: 8–14. doi:10.1890/0012-9658(2000)081[0008:PPBATP].0.CO;2].
  9. ^ Odum, E. P.; Barrett, G. W. (2005). Fundamentals of ecology. Brooks/Cole. p. 598. ISBN 978-0-534-42066-6.
  10. ^ "''Food chains and cycles,'' bitesize, BBC". 1970-01-01. Retrieved 2018-08-14.

An autotroph or producer, is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) from simple substances present in its surroundings, generally using energy from light (photosynthesis) or inorganic chemical reactions (chemosynthesis). They are the producers in a food chain, such as plants on land or algae in water (in contrast to heterotrophs as consumers of autotrophs). They do not need a living source of energy or organic carbon. Autotrophs can reduce carbon dioxide to make organic compounds for biosynthesis and also create a store of chemical energy. Most autotrophs use water as the reducing agent, but some can use other hydrogen compounds such as hydrogen sulfide. Some autotrophs, such as green plants and algae, are phototrophs, meaning that they convert electromagnetic energy from sunlight into chemical energy in the form of reduced carbon.

Autotrophs can be photoautotrophs or chemoautotrophs. Phototrophs use light as an energy source, while chemotrophs use electron donors as a source of energy, whether from organic or inorganic sources; however in the case of autotrophs, these electron donors come from inorganic chemical sources. Such chemotrophs are lithotrophs. Lithotrophs use inorganic compounds, such as hydrogen sulfide, elemental sulfur, ammonium and ferrous iron, as reducing agents for biosynthesis and chemical energy storage. Photoautotrophs and lithoautotrophs use a portion of the ATP produced during photosynthesis or the oxidation of inorganic compounds to reduce NADP+ to NADPH to form organic compounds.


Biomagnification, also known as bioamplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain. This increase can occur as a result of:

Persistence – where the substance cannot be broken down by environmental processes

Food chain energetics – where the substance's concentration increases progressively as it moves up a food chain

Low or non-existent rate of internal degradation or excretion of the substance – often due to water-insolubility

Biological magnification often refers to the process whereby certain substances such as pesticides or heavy metals work their way into lakes, rivers and the ocean, and then move up the food chain in progressively greater concentrations as they are incorporated into the diet of aquatic organisms such as zooplankton, which in turn are eaten perhaps by fish, which then may be eaten by bigger fish, large birds, animals, or humans. The substances become increasingly concentrated in tissues or internal organs as they move up the chain. Bioaccumulants are substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted.

Consumer (food chain)

Consumers are organisms that eat organisms from a different population. These organisms are formally referred to as heterotrophs, which include animals, some bacteria and fungi. Such organisms may consume by various means, they are called primary consumers.

Consumer–resource interactions

Consumer–resource interactions are the core motif of ecological food chains or food webs, and are an umbrella term for a variety of more specialized types of biological species interactions including prey-predator (see predation), host-parasite (see parasitism), plant-herbivore and victim-exploiter systems. These kinds of interactions have been studied and modeled by population ecologists for nearly a century. Species at the bottom of the food chain, such as algae and other autotrophs, consume non-biological resources, such as minerals and nutrients of various kinds, and they derive their energy from light (photons) or chemical sources. Species higher up in the food chain survive by consuming other species and can be classified by what they eat and how they obtain or find their food.

David Edgerton

David R. Edgerton (February 26, 1927 – April 3, 2018) was an American entrepreneur and the founder of the Burger King Corporation. On March 1, 1954, he opened a franchise outlet of the restaurant chain Insta Burger King in Miami, Florida. On June 1 of the same year, he met James McLamore and the two founded the Burger King Corporation. Edgerton graduated from Cornell University. He served on the advisory board of Avantcare, Inc.


In biology, detritus () is dead particulate organic material (as opposed to dissolved organic material). It typically includes the bodies or fragments of dead organisms as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose (or remineralize) the material. In terrestrial ecosystems, it is encountered as leaf litter and other organic matter intermixed with soil, which is denominated "soil organic matter". Detritus of aquatic ecosystems is organic material suspended in water and piling up on seabed floors, which is referred to as marine snow.

Dixy Chicken

Dixy Chicken is a fast food chain that specializes in halal chicken. The company was founded by two British Pakistanis, who offered halal versions of products found in McDonald's and KFC. It is owned by an English company, SABT2 Limited. Dixy Chicken was founded in 1986, and has 110 outlets within the United Kingdom.

There are four in Syria, and one each in France, Norway, and Egypt, as well as India, Brunei, Pakistan and the United Arab Emirates.

Ecological pyramid

An ecological pyramid (also trophic pyramid, eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bio productivity at each trophic level in a given ecosystem.

Biomass pyramids show how much biomass (the amount of living or organic matter present in an organism) is present in the organisms at each trophic level, while productivity pyramids show the procreation or turnover in biomass. There is also pyramid of numbers which represent the number of organisms in each trophic level. They may be upright (e.g. Grassland ecosystem), inverted (parasitic ecosystem) or dumbbell shaped (forest ecosystem).

Energy pyramids begin with producers on the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat flesh, then omnivores that eat both plants and flesh, and so on). The highest level is the top of the food chain.

Energy flow (ecology)

In ecology, energy flow, also called the calorific flow, refers to the flow of energy through a food chain, and is the focus of study in ecological energetics. In an ecosystem, ecologists seek to quantify the relative importance of different component species and feeding relationships.

A general energy flow scenario follows:

Solar energy is fixed by the photoautotrophs, called primary producers, like green plants. Primary consumers absorb most of the stored energy in the plant through digestion, and transform it into the form of energy they need, such as adenosine triphosphate (ATP), through respiration. A part of the energy received by primary consumers, herbivores, is converted to body heat (an effect of respiration), which is radiated away and lost from the system. The loss of energy through body heat is far greater in warm-blooded animals, which must eat much more frequently than those that are cold-blooded. Energy loss also occurs in the expulsion of undigested food (egesta) by excretion or regurgitation.

Secondary consumers, carnivores, then consume the primary consumers, although omnivores also consume primary producers. Energy that had been used by the primary consumers for growth and storage is thus absorbed into the secondary consumers through the process of digestion. As with primary consumers, secondary consumers convert this energy into a more suitable form (ATP) during respiration. Again, some energy is lost from the system, since energy which the primary consumers had used for respiration and regulation of body temperature cannot be utilized by the secondary consumers.

Tertiary consumers, which may or may not be apex predators, then consume the secondary consumers, with some energy passed on and some lost, as with the lower levels of the food chain.

A final link in the food chain are decomposers which break down the organic matter of the tertiary consumers (or whichever consumer is at the top of the chain) and release nutrients into the soil. They also break down plants, herbivores and carnivores that were not eaten by organisms higher on the food chain, as well as the undigested food that is excreted by herbivores and carnivores. Saprotrophic bacteria and fungi are decomposers, and play a pivotal role in the nitrogen and carbon cycles.The energy is passed on from trophic level to trophic level and each time about 90% of the energy is lost, with some being lost as heat into the environment (an effect of respiration) and some being lost as incompletely digested food (egesta). Therefore, primary consumers get about 10% of the energy produced by autotrophs, while secondary consumers get 1% and tertiary consumers get 0.1%. This means the top consumer of a food chain receives the least energy, as a lot of the food chain's energy has been lost between trophic levels. This loss of energy at each level limits typical food chains to only four to six links.

Fast food restaurant

A fast food restaurant, also known as a quick service restaurant (QSR) within the industry, is a specific type of restaurant that serves fast food cuisine and has minimal table service. The food served in fast food restaurants is typically part of a "meat-sweet diet", offered from a limited menu, cooked in bulk in advance and kept hot, finished and packaged to order, and usually available for take away, though seating may be provided. Fast food restaurants are typically part of a restaurant chain or franchise operation that provides standardized ingredients and/or partially prepared foods and supplies to each restaurant through controlled supply channels. The term "fast food" was recognized in a dictionary by Merriam–Webster in 1951.Arguably, the first fast food restaurants originated in the United States with White Castle in 1921. Today, American-founded fast food chains such as McDonald's (est. 1940) and KFC (est. 1952) are multinational corporations with outlets across the globe.

Variations on the fast food restaurant concept include fast casual restaurants and catering trucks. Fast casual restaurants have higher sit-in ratios, offering a hybrid between counter-service typical at fast food restaurants and a traditional table service restaurant. Catering trucks (also called food trucks) often park just outside worksites and are popular with factory workers.

Food Chain (Adventure Time)

"Food Chain" is the seventh episode of the sixth season of the American animated television series Adventure Time. The episode was written, storyboarded, and directed by Japanese anime director Masaaki Yuasa and guest stars Regular Show storyboard artist Minty Lewis as Erin the caterpillar.

The series follows the adventures of Finn (voiced by Jeremy Shada), a human boy, and his best friend and adoptive brother Jake (voiced by John DiMaggio), a dog with magical powers to change shape and grow and shrink at will. In this episode, Finn and Jake learn about the food chain after being turned into its different parts—small birds, big birds, bacteria, plants, and finally caterpillars—by Magic Man (voiced by Tom Kenny). As Finn and Jake journey along the food chain, they meet another character named Erin, whom Finn falls in love with and attempts to marry. The episode concludes with all the main characters singing a song about how the food chain works.

The episode was the second (following David OReilly's fifth season installment "A Glitch is a Glitch") in the series to have been directed by someone not affiliated with the series. On the night that it aired, "Food Chain" was watched by a total of 1.97 million viewers. The episode received largely positive reviews from critics, and was nominated for both an Annie Award and an Annecy International Animated Film Festival Award.

Food Chain (Buffy comic)

Buffy the Vampire Slayer: Food Chain is a trade paperback collecting comic stories based on the Buffy the Vampire Slayer television series. 'Food Chain was the largest Buffy graphic novel to come out before the Buffy: Omnibus volumes.


A heterotroph (; Ancient Greek ἕτερος héteros = "other" plus trophe = "nutrition") is an organism that cannot produce its own food, relying instead on the intake of nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but not producers. Ninety-five percent or more of all types of living organisms are heterotrophic, including all animals and fungi and some bacteria and protists. The term heterotroph arose in microbiology in 1946 as part of a classification of microorganisms based on their type of nutrition. The term is now used in many fields, such as ecology in describing the food chain.

Heterotrophs may be subdivided according to their energy source. If the heterotroph uses chemical energy, it is a chemoheterotroph (e.g., humans and mushrooms). If it uses light for energy, then it is a photoheterotroph (e.g., green non-sulfur bacteria).

Heterotrophs represent one of the two mechanisms of nutrition (trophic levels), the other being autotrophs (auto = self, troph = nutrition). Autotrophs use energy from sunlight (photoautotrophs) or inorganic compounds (lithoautotrophs) to convert inorganic carbon dioxide to organic carbon compounds and energy to sustain their life. Comparing the two in layman's terms, heterotrophs (such as animals) eat either autotrophs (such as plants) or other heterotrophs, or both.

Detritivores are heterotrophs which obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). Saprotrophs (also called lysotrophs) are chemoheterotrophs that use extracellular digestion in processing decayed organic matter. It is a term most often associated with fungi. The process is most often facilitated through the active transport of such materials through endocytosis within the internal mycelium and its constituent hyphae.

ISO 22000

ISO 22000 is a standard developed by the International Organization for Standardization dealing with food safety. It is a general derivative of ISO 9000.

Marine ecosystem

Marine ecosystems are among the largest of Earth's aquatic ecosystems and are distinguished by waters that have a high salt content. These systems contrast with freshwater ecosystems, which have a lower salt content. Marine waters cover more than 70% of the surface of the Earth and account for more than 97% of Earth's water supply and 90% of habitable space on Earth. Marine ecosystems include nearshore systems, such as the salt marshes, mudflats, seagrass meadows, mangroves, rocky intertidal systems and coral reefs. They also extend outwards from the coast to include offshore systems, such as the surface ocean, pelagic ocean waters, the deep sea, oceanic hydrothermal vents, and the sea floor. Marine ecosystems are characterized by their associated biological community of interacting organisms and their physical environment.

Ray Kroc

Raymond Albert "Ray" Kroc (October 5, 1902 – January 14, 1984) was an American businessman. He joined the California company McDonald's in 1954, after the McDonald brothers had franchised 6 locations out from their original 1940 operation in San Bernardino. Setting the stage for national expansion with the help of Kroc, eventually leading to a global franchise, making it the most successful fast food corporation in the world. Controversially, Kroc would present himself as the founder of McDonald's during his later life. Kroc was included in Time 100: The Most Important People of the Century, and amassed a fortune during his lifetime. He owned the San Diego Padres baseball team from 1974 until his death in 1984.

Richard and Maurice McDonald

Richard James and Maurice James McDonald were American siblings who founded the McDonald's restaurant in San Bernardino, California, and inventors of the "Speedee Service System," now commonly known as "fast food".

Taco Mayo

Taco Mayo Restaurant is a Mexican-American fast food chain based in Oklahoma City, Oklahoma.

Trophic level

The trophic level of an organism is the position it occupies in a food chain. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it is from the start of the chain. A food chain 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 food "web". Ecological communities with higher biodiversity form more complex trophic paths.

The word trophic derives from the Greek τροφή (trophē) referring to food or nourishment.

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