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Food Chain A food chain is a linear sequence of links in a food webs

from a species that are called producers in the web and en

species that is called decomposers species in the web.

A food chain also shows how the organisms are related wi

other by the food they eat.

Food chains were first introduced by the African-Arab sciephilosopher Al-Jahizin the 9th century and later populariz

book published in 19! by Charles "lton# which also introd

food web concept.

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A food chain differs from a food web# because thecomple$ polyphagousnetwork of feeding relations are aginto trophic species and the chain only followslinear monophagouspathways.

A common metric used to quantify food web trophic structuchain length. %n its simplest form# the length of a chain is th

of links between a trophic consumer and the base of the wemean chain length of an entire web is the arithmetic a&eraglengths of all chains in a food web.

Food Chain

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Food Chain 'ength and (sage

)he food chain*s length is a continuous &ariable that pro&ides a meapassage of energy and an inde$ of ecological structure that increasfrom the lowest to the highest trophic +feeding, le&els.

Food chains are often used in ecological modeling +such as a threfood chain,. )hey are simplified abstractions of real food webs# but their dynamics and mathematical implications.

"cologists ha&e formulated and tested hypotheses regarding the naecological patterns associated with food chain length# such as increlength with ecosystem size# reduction of energy at each succelevel# or the that long food chain lengths are unstable.

Food chain studies ha&e had an important role in ecotoxicology sttracing the pathways and biomagnification of en&ironmental contam

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Food Chain 'ength

Food chains &ary in length from three to six or more EX:

A food chain consisting of a grass# a rabbit# a hawk conthree le&els whereas a food chain consisting of grass# grasshopper# a rat# a snake and finally a hawk consists

le&els.

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Food Chain Producers# such as plants# are organisms that utilize solar energ

energy to synthesize starch. All food chains must start with a prod

onsumersare organisms that eat other organisms in most fooall the organisms in a food chain are consumers.

i. /e call animals that eat plants - primary !first" consumers#

ii. )he ne$t group are carni&ores or omni&ores. )hey eat the prim

consumers and are called 0 secondary consumers#

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eep-2ea Food Chain

%n the deep sea# food chains centeredaround hydrothermal ventse$ist in the absence ofsunlight. hemosynthetic bacteria and archaeacanuse hydrogen sulfide from hydrothermal &ents as anenergy source +$ust as plants use sunlight, toproduce carbohydrates they form the base of thefood chain.

%n a deep-sea food chain# tube worms# clams# andmussels harbor the chemosynthetic bacteria andmake use of the food they produce. )hey are alleaten by crabs# which in turn they may be consumedby an octopus.

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"cological 3yramids

An ecological pyramid+also trophic pyramidor enepyramid, is a graphical representation designed to shothe biomass or biomass producti&ity at each trophic le&gi&en ecosystem.

%iomassis the amount of li&ing or organic matter pres

organism. %iomass pyramidsshow how much biomass is prese

organisms at each trophic le&el# while productivitypyramidsshow the production or turno&er in biomass.

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"cological 3yramids

"cological pyramids begin withi# producers4 herbivores4 carnivores that eat herbiv

carnivores that eat those carnivores 4 and so on...

.

)here are basically 5 types of ecological pyramidsi. Pyramid of biomass

ii. Pyramid of productivity

iii. Pyramid of numbers

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3yramid of biomass

An ecological pyramid of biomassshows the relationship bebiomass and trophic le&el by quantifying the biomass present atrophic le&el of an ecological community at a particular time. )yare grams per meter or calories per meter&.

)he pyramid of biomass may be 6inverted7.

i. For e$ample# in a pond ecosystem# the standing

crop of phytoplan'ton# at any gi&en point will be lower than

of the heterotrophs# such as fish and insects. )his is e$plaine

phytoplankton reproduce &ery quickly# but ha&e much shorte

li&es.

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3yramid of producti&ity

An ecological pyramid of productivityis often more showing the production or turno&er of biomass at each le&el. %nstead of showing a single snapshot intime# producti&ity pyramids show the flow of energy thrthe food chain. )ypical units are grams per meter& pecalories per meter& per year.

/hen an ecosystem is healthy# this graph produces astandard ecological pyramid. )his is because in ordeecosystem to sustain itself# there must be more energlower trophic levels than there is at higher trophic l

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