Ecology

All living organisms are surrounded by the environment. The environment is the sum total of all living and non-living factors that surround and influence an organism. Organisms and environment are interdependent, inter-related and mutually reactive.

The study of interaction or inter-relationship of organisms with their environment is called ecology.

The ‘Ecology’ term was coined by Ernst Haeckel (1866). Ecology is also related to ecosystem.

Ecosystem is a self-sustained unit of living things (plants, animals and decomposers) and their non-living environment (soil, air and water etc). Both the components are essential for the sustenance of life. Ecosystem term was given by Arthur Tansley.

1.0Habitat

All the living organisms (plants and animals) prefer to live in those places which are best suited to their needs. The place (or surroundings) where a plant or an animal lives is called its habitat. A habitat provides food, water, air, light, shelter (protection) and a place for breeding to the plants and animals living in it. The habitats can be divided into two main groups - Terrestrial habitats and Aquatic habitats.

2.0Components of ecosystem

The various components of an ecosystem may be grouped into two main types -

Abiotic (non-living) components

These include the non-living physico-chemical factors of the environment.

Abiotic factors include:

1. Inorganic substance: Inorganic substances (carbon, nitrogen, oxygen, calcium, phosphorus, etc.) and their compounds (water, carbon dioxide, etc.) constitute the main abiotic component.

2. Physical environment: These include air, water and soil.

3. Climatic factors: These include light, temperature, humidity, wind, rainfall, water, etc. soil, substrate, topography, minerals, pH, etc.

Biotic (living) components

Biotic components of an ecosystem include 3 types of organisms -

1. Producers: Those organisms which can prepare their own food from simple inorganic substances like carbon dioxide and water by using sunlight in the presence of chlorophyll. e.g., green plants.

2. Consumers: Those organisms which consume food or eat food prepared by producers are called consumers. The consumers depend on producers for food, directly or indirectly. All the animals are consumers.

3.0Consumers can be further divided into three groups:

(a) Herbivores - Those animals which eat only plants are called herbivores. e.g., Buffalo, goat, sheep, horse, deer, camel, grasshopper, etc.

Since, herbivores obtain their food directly from plants or producers therefore herbivores are primary consumers.

(b) Carnivores - Those animals which eat only other animals as food are called carnivores or those animals which eat the flesh of other animals are called carnivores. e.g., Lion, tiger, frog, vulture, etc.

The small carnivores which feed on herbivores (primary consumers) are called secondary consumers. The large carnivores or top carnivores which feed upon the small carnivores or secondary consumers are called tertiary consumers. e.g., Lion, tiger, hawk, etc.

(c) Omnivores: Those animals which eat both plants and animals are called omnivores or those animals which eat plant food as well as the flesh of other animals. e.g., Man, dog, crow, sparrow, bear and ant etc.

3. Decomposers: The micro-organisms which break down the complex organic compounds present in dead organisms like dead plants and animals and their products like faeces, urine into simpler substances are called decomposers. e.g., Bacteria and fungi.

4.0Importance of decomposers:

1. They decompose the dead bodies of animals and plants thus acts as cleansing agents of the environment.

2. They help in recycling the material in biosphere.

3. They maintain the fertility of soil.

4. If there were no decomposers, the earth would have been a heap of dead organisms.

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