Food Web

Food Web

All processes in this world, whether living or non-living, needs energy. Living organisms are capable of producing energy or getting it through predation. They need this energy to maintain cells and tissues. It is also required for supporting voluntary and involuntary actions of the human body and to manage multiple processes within the body like reproduction, cell division, metabolism, digestion, circulation, excretion, and much more.

The ultimate source of energy on Earth is the Sun. No energy can be produced without the sun. All living beings, especially plants capture the solar energy and utilize it for their food production. This process is called photosynthesis. There are unique interactions and relationships which are involved in the transportation of energy. The energy, once produced and captured, is distributed throughout the various organisms. This transfer of energy is termed as the food web.

A food chain is a network where the producers are used or consumed by the predator (secondary & primary carnivores) and then the detritivores and finally by decomposers. When many such individual food chains occur in an ecosystem, it is known as Food Web. In other words, food web is a network of many different food chains.

A food chain shows a direct transfer of energy between organisms. As every organism can feed on multiple things, a food web is a much more realistic and simplified method of transferring energy in an ecosystem.

Producers

Organisms that can synthesize their own food and usually serve as the foundation for all food chains. For example – plants, algae and few species of bacteria. They prepare their own food by converting sunlight into chemical energy and this process is called photosynthesis. They use energy from the sunlight for converting carbon dioxide into simple glucose which is easily broken down to produce energy. This energy is then stored in the form of sugars for later use.

The simple diagram of the Food web is as shown below.

Food Pyramid

Primary Consumers

They are also called herbivores animals who eat producers or plants. Sometimes, these primary consumers become prey for other animals that sit higher on the food chain. Some of the primary consumers or herbivores living on the land are chipmunks, mice, horses, birds, deer and some insects. Fish, zooplankton, snails, sea urchins are few marine primary consumers.

10 Percent Energy Rule

Even though primary consumers feed on producers, they are still getting their energy from the sun. As the primary consumers feed on plant and break down the food particles to release the energy. Primary consumers do not get 100% of the sun’s energy from the producers as only some amount of the sun’s energy is utilized by the plant to synthesize their food. In fact, they only get 10% of the energy. This is termed as the 10% Rule, which states that only 10 percent of the energy available gets passed onto the next level of consumers.

Secondary Consumers

These are animals who feed on primary consumers. They usually eat meat and are termed as predators. Lion, hawks, snakes, coyotes, wolves, and spiders are few terrestrial secondary consumers.

Tertiary Consumers

They are the ones who feed on the secondary consumers. They are thus called the top predator. They are also termed as apex predators and have no natural enemies. Naturally, you would assume that humans are at the top of the food chain, but they are not.

Why are humans not at the top of the food chain?

Scientist categorize the organisms on the food chain by trophic levels. A “Trophic level” means how far an organism is from the start of the food chain. For instance, plants are considered to be at trophic level 1, and the apex predators are usually placed at level 4 or 5. According to scientists, humans are placed on a trophic level of 2.21. This actually makes sense because when was the last time you ate a Bengal tiger?


Practise This Question

The amino acid constituent of a protein is given:  Methionine, Valine, Tyrosine, Arginine, Threonine, Stop codon. Choose the correct DNA sequence from below which codes for it.