Types of Food Web and a Balanced Ecosystem

Introduction to Food Web

• Food web: The network of interrelated and interconnected food chains that include producers, consumers, and decomposers, is called the food web. It is a more realistic way of looking at the relationship between plants and animals in an environment. Several food chains are linked together in a food web. A predator from one food chain may be linked to the prey of another food chain.

Food webs show all the food chains in an ecosystem.

Fig No. 1 Food web

Explanation:

Food web can be defined as, “a network of food chains which are interconnected at various tropic levels, so as to form a number of feeding connections amongst different organisms of a biotic community”. It is also known as the consumer resource system.

Fig No. 2 Food web

Important facts

• A node represents an individual species, a group of related species, or different stages of a single species.
• A link connects two nodes. Arrows represent links and always go from prey to predator.
• The lowest tropic levels are called basal species.
• The highest tropic levels are called top predators.
• Movement of nutrients is cyclic but energy is unidirectional and non-cyclic.

Fig No. 3 Food web diagram

Food web vs. Food chain

Food Web

• Food webs look at how multiple food chains interact with each other. Since most animals or plants might be part of several different food chains, they can create a food web that is made up of lots of producers, consumers, and decomposers.

Fig No. 4 Food web

Food Chain

• A food chain shows you how one organism eats another and transfers its energy.
  For example, a deer eats grass, and the deer is eaten by the lion. The food chain looks like this: grass – deer – lion.

Fig No. 5 Food chain

Energy Movement

Energy flows through the different trophic levels. It begins with the energy from the sun that autotrophs use to produce food. This energy is transferred up the levels as the different organisms are consumed by members of the above levels.

Approximately 10% of the energy that is transferred from one trophic level to the next is converted to biomass.

Biomass refers to the overall mass of an organism or the mass of all the organisms that exist at a given trophic level. Since organisms expend energy to move around and go about their daily activities, only a part of the energy consumed is stored as biomass.

Characteristics of a Food Web:

1.    Unlike food chains, food webs are never straight. Instead, each food web is formed by the interlinking of food chains.

2.    A food web provides alternative pathways of food availability. For example, if a particular species of a producer is destroyed by a disease in the ecosystem, the herbivores of that area can feed on other species of producers. Similarly, Secondary consumers (e.g., predatory birds) may feed on rats or mice in the event of a decrease in the population of rabbits in that area on which they also commonly feed.

3.    Greater alternatives available in a food web make the ecosystem more stable.

4.    Food webs also help in checking the overpopulation of highly fecundive species of plants and animals.

5.    Food webs also help in ecosystem development.

Different Types of Food Web:

Food webs exist in a variety of biomes. Because each habitat is unique, each food web is slightly different. Explore different plants, animals, and decomposers that can be found in deserts, savannas, forests, and marine environments.

Desert

A desert is a habitat with little water. Deserts are not all hot either. Some deserts are very cold. In the desert food web, you will find:

• Producers: Cacti, bushes, acacias, flowers, brush
• Primary Consumers: Insects, lizards, rodents
• Secondary Consumers: Tarantulas, scorpions, lizards, snakes
• Tertiary Consumers: Hawks, foxes

Forest

Forests have lots of trees and other plants. They are dense with lots of different vegetation for animals. Forest food web includes:

• Producers: Plants, fruits, nuts, seeds, flowers
• Primary Consumers: Deer, squirrels, frogs, birds, pikas
• Secondary Consumers: Pine marten, jackrabbits, ravens, ringtails
• Tertiary Consumers: Bobcats, mountain lions, coyotes

Savanna

A savanna biome has a lot of grass for animals to graze on. These habitats are found in Africa, Australia, and even South America. Savana Food web includes:

• Producers: Star grass, oat grass, and acacia
• Primary Consumers: Grasshoppers, ants, termites, warthogs, gazelle, impala, mice, wildebeest
• Secondary Consumers: Pangolins, aardvarks, mongooses
• Tertiary Consumers: Wild dogs, lions, cheetahs, caracals, servals, eagles

Marine

Underwater creatures like variety too. In a marine environment, examples of components we will find in the food web include:

• Producers and Decomposers: Seagrass, seaweed, algae, plankton, bacteria
• Primary Consumers: Turtles, damselfish, crab, shrimp
• Secondary Consumers: Octopuses, triggerfish, squid, krill
• Tertiary Consumers: Seagulls, penguins, elephant seals, whales

Management of Food Web:

Food webs are easily unbalanced, especially if one population of organisms in the web dies or disappears. This may happen for a number of reasons, including:

• Over–predation or hunting
• Disease
• Pollution
• Use of pesticides
• Lack of food (or other resources)
• Emigration

For example, if all the baboons were killed by hunters in the food web here, the leopard would have only the impala to eat. So, the impala population would decrease. The scorpion population may increase because of less predation by baboons, but if there are more scorpions, they will eat more locusts, reducing the locust population, and so on.

Fig No. 6 Food web

Balanced Ecosystem

• All elements in the ecosystem are connected to each other. 
• All processes in the ecosystem are linked together in a complex arrangement. (Food Web) 
• All natural ecosystems are stable and maintain a state of balance or equilibrium. 
• Systems that do not maintain equilibrium do not survive.

Fig No. 7 Balanced ecosystem

Summary

• The network of the interrelated and interconnected food chains that include producers, consumers, and decomposers is called the food web.
• The movement of nutrients in a food web is cyclic, but the movement of energy is unidirectional and non-cyclic.
• Energy flows through the different trophic levels.
• Not all energy is passed on in a food web.
• There are different types of food webs.
• All species are important and help to keep the ecosystem balanced.

Hunting, deforestation, pollution, etc., can cause unbalance in an ecosystem