Tag: food chain and food web

A food web consists of all the food chains in a single ecosystem. Each living thing in an ecosystem is part of multiple food chains. Each food chain is one possible path that energy and nutrients may take as they move through the ecosystem. All of the interconnected and overlapping food chains in an ecosystem make up a food web.  An ecosystem cannot support a large number of omnivores without supporting an even larger number of herbivores, and an even larger number of autotrophs and hence the biomass of autotrophs will be the heaviest as it present in abundant amount..

An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment, interacting as a system.  Sun is the source of energy 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. 

Omnivore is a consumption classification for animals that have the capability to obtain chemical energy and nutrients from materials originating from plant and animal origin. Often, omnivores also have the ability to incorporate food sources such as algae, fungi, and bacteria into their diet as well. Omnivores come from diverse backgrounds that often independently evolved sophisticated consumption capabilities. Although cases exist of herbivores eating meat and carnivores eating plant matter, the classification "omnivore" refers to the adaptations and main food source of the species in general. Various mammals are omnivores in the wild,  including humans and bear species.

The trophic level of an organism is the position it occupies in a food chain. The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat. If a grassland ecosystem has 10,000 kilocalories (kcal) of energy concentrated in vegetation, only about 1,000 kcal will be transferred to primary consumers, and very little (only 10 kcal) will make it to the tertiary level. Energy pyramids such as this help to explain the trophic structure of an ecosystem.

In nature, some organisms operate in the ecosystem not just at a single trophic level but more than one trophic levels which means that it may derive its food from more than one source. The organism may get eaten itself by another organism of higher trophic level. It may also feed on different organisms of lower trophic levels. In this way, various food chains are linked together in an ecosystem and the intersection of these food chains form a complex network called food web. 

Trophic levels in an ecosystem are formed by organisms linked in food chain. It starts from producer level and usually ends at secondary or tertiary consumer levels.

Mollusc constitutes the second largest phylum in the animal kingdom which includes a group of animals living on land, in marine water, and in fresh water. Mollusks include both herbivores and carnivores animal. They eat both plants and small animals. In an aquatic ecosystem, a mollusk acts as primary consumers, so it belongs to second trophic level (T2).