Concept of Habitat & Ecological Niche

{Habitat & Ecological Niche}

“The habitat of an Organism is the place where it lives, or the place where one would go to find it.” Habitat is also defined as

“The sum total of environmental factors of an individual, population or community in locality.” Thus, the habitat of the water “backswimmer” Notonecta is the swallow vegetation-choked areas (Littoral Zone) of ponds & lakes; that is where one would go to collect this particular organism.

Habitat commonly refers to a large area or the place occupied by entire community. E.g.: - Pond, Lake, River, Estuary, Ocean, Forest, Desert, Grassland, Wood-land etc. Like the habitat of the sand sage grassland community is the series of sandy soil occurring along the north sides of rivers in the Southern Great Plains region of the United States.

However, it may be as smaller as a Burrow, Bark of tree or intestine of an Ant.

On the other hand “Ecological Niche, is a more inclusive term that includes not only the physical space occupied by an organism but also its functional role in the community (e.g.: - its trophic position) and its position in environmental gradients of temperature, moisture, pH, Soil and other condition of existence.” Grinnel (1971) used term Niche.

These three aspects of the ecological niche can be conveniently designated as the: -

      1. Spatial or Habitat Niche: It refers to the Physical Space occupied by an organism. E.g. Distribution of seven species of Millipedes in forest floor of a Maple Oak forest (O’Neill, 1971).

      2. Trophic Niche: It deals with the trophic position of an organism.

E.g. Notonecta & Corixa live in the same aquatic habitat i.e. Pond, but are of different trophic niche. Notonecta is a Predator while Corixa feeds largely on decaying vegetation.

      3. Multidimensional or Hyper volume niche: It’s considered as “abstract n-dimensional inhabitant hype volume (By G.E.Hutchinson, 1965).

Consequently, the ecological niche of an organism depends not only on where it lives but also on what it does (how it transforms energy, behaves, responds to and modifies its physical & biotic environment) & how it is constrained by other species.

By analogy, Ecologist E.P.Odum said that “the Habitat is the organism’s address and the Niche is its Profession.”

Food Chain

   

“The transfer of food energy from the producers, through a series of organisms (herbivores to carnivores to decomposers) with repeated eating & being eaten, is known as Food Chain.” It includes:-

1) Primary Consumers or Herbivores:  They are animals which feed on plants or plant products.

Eg. grasshoppers and several other insects, rabbit. Hare, deer, antelope, elephant, zooplankton etc.

Herbivores are also called key industry animals because they convert plant matter in to animal matter.

2) Secondary Consumers or primary Carnivores: They ingest or prey upon herbivores animals.

Eg. Frog, predator, Insects, several Birds, Fishes, Wild Cat, Fox, Jackal (also Scavenger) etc.

3) Tertiary Consumers or Secondary Carnivores: They are larger carnivores which prey upon primary carnivores.

Eg. Wolf (feeds on fox), Snake (Prey upon frog).

4) Top Carnivores: They are the last order consumers or carnivores which are not preyed upon by other animals because of their size, agility & ferociousness,

Eg. Shark, Crocodile, Eagle, Peacock, Tiger, Lion.

Some common food chains are:-

**Land:

a) Grass-->Grass Hoppers-->Frog-Snakes-->Peacock/Falcon

b) Vegetation-->Rabbit-->Fox-->Wolf-->Tiger

**Aquatic:

a) Phytoplankton-->Zooplankton-->Small Crustaceans-->Predator Insects-->         Small Fish-->Larger Fish-->Crocodile

In Nature we distinguish two general types of Food Chains:

1) Grazing Food Chain: - This type of food chain starts from the living green plants goes to grazing herbivores & on to carnivores. It is directly dependent on influx of solar radiation.

2) Detritus Food Chain: - This type of food chain goes from dead organic matter to microorganisms & then to organisms feeding on detritus & their predators. Such ecosystems are less dependent on direct solar energy.

Ecology-“The Study of Structure & Function of Nature”

“Ecology word is combination of two Greek words “Oikos (home, house or dwelling place) & Logos (the study of).” This describes relation of organisms & their surroundings (environment).

When we go much deeper in understandings of Nature, broadly, we find two important aspects i.e. organisms and its surroundings (environment). Which, mutually co-related and dependent on each other with much complex relation.

Time to time many scientist used and coined different terminologies to study Nature.

French zoologist Isodore Geoffroy st.Hilaire in 1859 had coined the term “Ethology” for “Study of the relations of the organisms within the family & society in the aggregate & in community.”

Charles Darwin in his book “On the Origin of Species” (1859) has used several potential terms, which can be used in explanation of Modern Ecology in broader way.

In 1886 Haeckel used the term Ecology as “the knowledge of the sum of the relations of organisms to the surroundings outer world to organic & inorganic condition of existence.”

R Mishra (1967) described Ecology as “Interactions of form, functions & factors.” These three factors combinedely construct the triangle of Nature.

Odum in 1969 define Ecology as “the study of structure & function of Nature.

Krebs (1985) has defined Ecology as “Ecology is the scientific study of the interactions that determine the distribution & abundance of organisms.”

In more recent updates, the terminology “Biotic (Living) & Abiotic (non-living) used in describing the Ecology as its component and both are related with each other & functions accordingly as a proper system.