Explain food-chain and food web with suitable examples.

Although biotic and abiotic components are separate by their complex relationship is balanced and functional, which can be explained by following points:

(1) Energy flow, (2) Food chains, (3) Food web

(1) Energy Flow: Existence of organisms depend on energy and main source of energy on the earth is the sunlight. Energy is required by the organisms for their various al activities. We know that two biotic components in the system are autotrophs and heterotrophs. Only green plants are capable to use sun-light r energy source and this energy is transferred from producers to consumers.
During transfer of energy there is loss of some part of energy and energy loss also occurred during respiration.It indicates that energy flow is unidirectional.

In any ecosystem only 1 percent solar energy can be used by green  plants for synthesis of food and such traped energy is responsible for an ecosystem, herbivore obtain energy – from green plants and secondary consumers obtain only 10% energy of a primary consumer (herbivore). At every level energy is lost in similar way. Energy flow and its distribution in the ecosystem is according to the Laws of Themodynamics which are as follows:

(1) First Law: Amount of energy is constant in the world and hence neither energy can be synthesized nor can be destroyed. Energy can be converted from one state to another state. Green plants convert light energy into chemical energy.

(2) Second Law: During energy transfer, some part of energy is lost. This energy loss is diffused in the environment mostly in the form of temperature and remaining is stored in the form of tissues.

Food Chains : The transfer of food energy from the producers through various organisms as they depend for food on one another (herbivore to carnivore to decomposers) with repeated eating and being eaten is known as food chain. In any food chain producers constitute the first trophic level. The energy stored in green plants is used by the herbivores (primary consumers) which constitute the second trophic level. Carnivores (secondary consumers) eat the herbivores and constitute the third trophic level As much, as longer chain, the highest consumer will get less energy because 90% energy is lost during each transfer in the form of temperature etc. are known as food web. Energy flow in a food chain is although unidirectional but through various path in a food web.

As much as complex food web in a ecosystems, the system will be more stable because consumers can obtain their food by various organisms. If there is scarcity of a particular kind of organisms then other organisms may be used as a food in a complex type of a food web. Terrestrial animals have following adaptations

  1. Cursorial adaptations: These adaptations provide ability for fast running. The body is streamlined and digitigrade so they can move through digits. Some are unguligrade for example horse.
  2. Fossorial adaptations : Many animals live in burrows. Body of these animals is Cylindrical e.g. snakes. Tail absent or reduced. Eyes are small and head is blunt.
  3. Desert adaptations : Lives of desert animals depend on water conservation. Some lizards for example moloch has skin capable to absorb moisture and a special structure in the alimentary canal is found in the camel for water storage. Sweat glands are absent in camel.

In Burrowing animals nostrils are on upper side of head to prevent from dust and large scales are present on the head indicate desert adaptation. Colour of desert animals is usually somewhat similar with soil.

  1. Scansorial adaptations : Many animals climb for obtaining food and defense. Lizards have adhesive glands for climbing on the walls. Similarly squirrels, tree frog, monkey etc. are able to run on the trees. These animals have prehensile tail, strong pectoral girdle, semicircular thorax, proximal part of forelimb is long and nailed digits, which are main adaptations.

Food chain : Any one sequence of species through which material and y passes is known as Food-chain. Food chain is a nutritional sequence in an Ecosystem.

Food-web: When number of food-chains are interlocked with each other, they make a very complex structure known as food-web. Food-web exhibits a complex inter-relationship of the populations of plan animals which exists in a particular system.

In other words, “The net work of inter-connected food chains in an ecosystem is called Food-web.”

Food-web exhibits a complex inter-relationship of the populations of plants and animals which exists in a particular ecosystem. In a Food-web each species is dependent upon other and the number of each link species must be sufficient for their continued existence.