WHAT IS ECOLOGY

INTRODUCTION OF ECOLOGY

 

 

Before going to read full ecology post, we should know about life and environment. Life

originated in our earth around four billion years ago. It is generally agreed that all life

forms of today evolved by a common descent from a single primitive life form. It is not

known how this early life form came into existence, but scientists think that it was a

natural process which took place perhaps 3,900 million years ago. The earliest claimed life

forms are tossilized micro-organisms or microfossils. They were found in iron and silica-

rich rockS which were once hydrothermal vents in the Nuvvuagittuq greenstone belt of

Quebec, Canada, and these rocks are as old as 4.28 billion years. If this is the oldest record

of lite on earth, it suggests an almost instaneous emergence of life after oceans were

formed 4.4 billion years ago. Moreover a scientific study showed that geological formation

of stromatolites of 3.45 billion years old contain fossilized cyanobacteria and stromatolites

were also the oldest known life records on earth.

The basic chemicals from which life is supposed to have formed are methane (CH),

ammonia (NH), hydrogen sulphide (H,S), carbon dioxide (CO), carbon monoxide (CO),

phosphate (PO) and water. Molecular oxygen (O,) or ozone (O) were either rare or

absent during that period. Thus initially the earth's atmosphere had almost no free oxygen.

It was gradually changed to the present day oxygenic atmosphere containing around 20%

free oxygen, so that the aerobic organisms can use oxygen for respiration. Initially single

celled organisms originated 4.1 billion years ago and then multicelullar organisms appeared

approximately 1.5 billion years ago. Land plants originated around 500 million years ago.

The modern man (Homo sapiens) arose around one to two lakh years ago. And now our

planet earth bears various kinds of lite forms starting from micro- organisms, upto fungi,

green plants and animals in a harmoneous manner. The living organisms are the important. 

components of biosphere. Only one percent of the species of living organisms are existent

to-day ana 99% of species have been lost from the earth's crust, which might have been

due to natural events or catastrophe leading to destruction of the living organisms. A very

800d example is the Cretaceous-Paleogene extinction, also known as the Cretaceous-

lertiary extinction, when a mass extinction of some three-quarters (3/74) of the animal and

Plant species on earth occurred approximately 66 million years ago. Still about 8.7 million

(t 1.3) species of living organisms are existing today according to a recent report or

Census of marine life (2011), the figure is based on a new analytical technique. Out of it,

6.5 million species occur on land and 2.2 million species are present in oceans. It is the

most precise calculation ever offered.

All organisms starting from the tiniest bacterium to the largest blue whale need a

place to live. Life is everywhere - in the oceans, beneath the soil, in the cold polar regions,

in hot springs and even in animal's body. The place on earth's surface where life dwells

is called the biosphere. Biosphere is capable of supporting life. Apart from the living

components, biosphere has non-living or abiotic components like water, air, soil, fire etc.

Each organism is living in a particular environment. Environment is the surroundings

in which a man, or animal or plant lives or operates. It is also the sum total of all

surroundings of a living organism, including natural forces and other living things, which

provide conditions for development and growth as well as of danger and damage.