Ecosystem Nutrition and Energy Flow

In a food chain where a deer feeds on producers and lion feeds on the deer then, the deer is a first order consumer and the lion is a second order consumer, and as the lion feeds in the deer, lion is the predator and the deer is the prey. 

When different food chains from different ecosystems (like grassland and forest) interact or overlap, the resulting complex network is described as a food web.

A food chain is a single linear path of energy flow, whereas a food web is a collection of many interlinked food chains that better represent the complexity of an ecosystem.

Apex of the food pyramid is the tip of the food pyramid. In the given food pyramid, peacock eats snakes which eat hoppers which in turn eats leaves of the plants. Hence, the peacock is the apex of food pyramid and plants are the base of the food pyramid.  Hoppers are primary consumer and snakes are secondary consumers of the given food pyramid.

Food web is interconnected food chains in an ecosystem. Extinction of a species in a food chain is compensated in food web. When a particular species in a food chain becomes extinct, it is compensated by the remaining generalized species at the same trophic level.

In a food chain, the carnivores eat up herbivores, or in other words, the secondary consumers consume the primary consumers. So, we can say that if the number of carnivores decreases, the number of herbivores like deer go on decreasing as they will not get eaten up. So, removal of most of the carnivores will result in an increased population of deer. 

In an ecosystem, there are various trophic levels. Each trophic level consists of a particular organisms. It consists of producers, consumers, decomposers. The first trophic level consists of producers such as plants. The second trophic level consists of primary consumers. The third trophic level consists of secondary consumers. There are certain organisms which occupy more than one trophic level in the same ecosystem at the same time. An example include sparrow. It feeds upon grains. Hence, it is called as primary consumer and occupies second trophic level. It also feeds upon insects. Hence, it is called as secondary consumer and occupies third trophic level.

There are various trophic levels in a food chain. The first trophic level consists of primary producers such as plant. The second trophic level consists of herbivores or primary consumers. The third trophic level consists of carnivores or secondary consumers. Decomposers are present at the top trophic level. Phytoplankton occupies the first trophic level in an ecosystem. The zooplankton feeding upon phytoplankton occupies the second trophic level in an ecosystem. Aquatic animals occupy any trophic level in an ecosystem. Aquatic animals such as zooplankton occupies first trophic level. Aquatic animals such as small fish occupies second trophic level. Aquatic animals such as large fish occupies third trophic level. The aquatic plants occupy first trophic level. 

A web of interconnected food chains is known as food web.

Trophic means food. The animals linked in the food chain form various trophic levels. A food chain is a series of organisms that eat and get eaten.

The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10% of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat. Food webs illustrate how energy flows through ecosystems, including how efficiently organisms acquire and use it. Autotrophs, producers in food webs, can be photosynthetic or chemosynthetic. They use light energy to synthesize their own food, while chemoautotrophs use inorganic molecules. Heterotrophs cannot synthesize their own energy, but must obtain it from autotrophs in food webs.

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.