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Food Chains and Food Webs

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Define BIODIVERSITY

Biodiversity describe the variety of plant and animal life that may exist in a particular area.

Biodiversity is  the total of all living organisms in an area such as a park, a lake or a province.

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Define BIODIVERSITY

This might include  bears, wolves, spruce trees, trout, frogs, and eagles in a Newfoundland ecosystem. It would not include elephants, tigers, crocodiles, or palm trees since these organisms are not normally found here.

The more types of organisms present in an ecosystem, the more diverse it is

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Define Food Chains

Food chains are a way of showing who eats whom in an  ecosystem. For example a spruce tree may get eaten by a deer who in turn gets eaten by a wolf. A single food chain illustrates only one part of what happens in an ecosystem.

Consider the following simple food chain with four links or  levels. Here we have plankton being eaten by capelin which get eaten by codfish. Of course, the codfish get eaten by the seals. Notice that the arrow points to the organism doing the eating:

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Define Food Chains

The following simple food chain contains four links or  levels. Plankton is eaten by capelin which gets eaten by codfish. The codfish gets eaten by the seals.

Notice that the arrow points to the organism doing the eating

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Food Chains (Example)

Plankton----- Capelin--------- Codfish------- Seal

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Define Food Web

A  food web is the combination of all of the food chains which exist within a community.

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Define Food Web (Example)

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Define Food Web (Example)

Most organisms have more than one  food supply. For example,  gulls eat crabs, mussels, prawn as well as whelks and limpets.

Each individual organism is involved in many food chains. These food chains interconnect to form a relationship called a food web.

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Define Competition

Since living space and food are limited, organisms must compete among themselves and with other species for the necessities of life and to survive.

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How does competition arise?

Competition arises when organisms have requirements in common and they must compete to meet their own needs.

When resources become scarce, competition becomes more intense, and eventually one of the species becomes eliminated.

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Competition among same species

Competition can occur between members of the same species.

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Competition among different species

Competition can also occur between members of different species.

Different species often compete for space, food, or water. For example the coyote and the lynx both compete for arctic hares (rabbits) as a source of food.

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Competition among different species

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Ecosystem Stability

Means that there is an ecological balance between the various organisms that make up the food web.

To be stable there must be a balance between food production, food consumption, and decaying of dead organisms and/or their wastes.

 

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Ecosystem Stability

Many interrelated food chains of an ecosystem give a community stability because every food level helps to control the numbers of the level below it.

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Ecosystem Stability

For example predators such as lions help to ensure the health of the zebras. Some biologists have even remarked that the predator is the prey's best friend!!!