FOOD WEB  By  Marcus Chukwu.

Food web is a set of interconnected food chain by which energy and materials circulate within an ecosystem. The food web is divided into two broad categories:

1.     the grazing web- which typically begins with green plants, algae, or photosynthesizing plankton and

2. the detrital web- which begins with organic debris.

These webs are made up of individual food chains. In a grazing web, materials typically pass from plants to plant eaters (herbivores) to flesh eaters(carnivores).

In a detrital web, materials pass from plant and animal matter to bacteria and fungi (decomposers), then to detrital feeders (detritivores), and then to their predators (carnivores).

Generally, many interconnections exist within food webs. For example, the fungi that decompose matter in a detrital web may sprout mushrooms that are consumed by squirrels, mice, and deer in a grazing web.

Robins typically feed on earthworms, which are detritivores that feed upon decaying leaves.

                                TROPHIC LEVELS

The food web can be viewed not only as a network of chains but also as a series of trophic (nutritional) levels. Green plants, the primary producers of food in most terrestrial food webs, belong to the first trophic level.

Herbivores, consumers of green plants, belong to the second trophic level. Carnivores, predators feeding upon the herbivores, belong to the third. Omnivores, consumers of both plant and animal belong to the second and third.

Secondary carnivores, which are predators that feed on predators, belong to the fourth trophic level. As the trophic level rises, the predators become fewer, larger, fiercer, and more agile.

At the second and higher levels, decomposers of available material function as herbivores or carnivores depending on whether their food is plant or animal material.

Marcus Chukwu teaches and writes on biology. He is currently based in Ibadan, Oyo State ,Nigeria and can be reached on – marcus.ifeanyichukwu@yahoo.com  tel:07032594088