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Every species has its own peculiar and perhaps unique set of environment requirements for survival.Unless these needs are met, extinction is certain.However ,these requirements are not totally inflexible,for the may vary throughout the lifetime inflexible,for the may vary throughout the lifetime of the individual and the history of species.Various ecological factors have been grouped and discussed in different ways. The environmental factors which influence the growth, distribution, abundance, behaviour and ultimate Survival of organisms are grouyinto two basic categories —

Non living or Abiotic environmental factors:- Non living or Abiotic factors are all types of interaction between the population and abiotic environment.

Living or Biotic environmental factors:- Living or Biotic factors are all types of interaction between different forms of life ,plants animals and micro organisms. According to Oosting(1948),the environment is a complex of variable factors which includes,soil,water, temperature ,Light,wind, gravity,plants,and animals. According to Mishra and Puri (1959), geology and soil is as the root of environment where as temperature,light ,water,wind and biotic as temperature are the shoot of environment. The ecological factors can be broadly classified into four groups —

(1) Climatic factors:- Climatic factors includes light , atmospheric temperature, precipitation, humidity, rainfall and winds.

(2)Edaphic factors:- It includes soil texture, chemical nature of soil, soil moisture, soil temperature,soil and soil organisms.

(3) Topographic factors:- It includes altitude i.e height of mountains,direction of mountain chain and valleys ,the steepness of slopes and exposure of slopes.

(4) Biotic factors:- it includes all types of interaction between different forms of life,plants, animals, and micro-organisms


Climatic factors play an important role in the distribution, behavior, and physiology of animals in the field of zoology. Some of the key climatic factors that are of particular importance to zoologists are:

Temperature: Temperature affects many aspects of animal behavior, physiology, and distribution. For example, temperature can influence the activity levels, growth rates, and reproductive cycles of animals. Animals may also adapt to temperature by seeking out habitats that provide optimal temperatures, or by modifying their behavior to regulate their body temperature.

Precipitation: Precipitation can influence the availability of water and food, as well as the quality of habitats for animals. For example, animals in arid regions may be adapted to conserve water, while those in regions with high precipitation may have adaptations to deal with wet conditions.

Wind: Wind can influence animal behavior and distribution by affecting the dispersal of seeds and spores, as well as the migration patterns of animals. Wind can also influence the availability of food resources and the likelihood of predation.

Humidity: Humidity can influence the ability of animals to regulate their body temperature and the availability of water resources. Animals that live in humid environments may have adaptations that allow them to conserve water, while those in dry environments may have adaptations that allow them to withstand low humidity.

Seasonal changes: Seasonal changes in temperature, precipitation, and daylight can influence animal behavior and physiology. For example, animals may migrate to different habitats or change their behavior to adapt to changes in food availability, mating seasons, and weather patterns.

(a) LIGHT:-

Light is one of the most important climatic factors, as it plays a crucial role in many biological and ecological processes. Light is a form of energy that is essential for photosynthesis, which is the process by which plants produce their own food. It also affects the behavior, growth, and development of many organisms, including animals and humans.

The intensity, duration, and quality of light can have a significant impact on the climate and the environment. The amount of light that reaches the Earth’s surface is affected by factors such as the angle of the sun, cloud cover, atmospheric pollution, and geographic location. Light also plays a role in the Earth’s heat balance, as it contributes to the warming of the planet.

Light is also an important factor in the regulation of daily and seasonal rhythms in many organisms. For example, the amount of daylight can influence the timing of flowering in plants, migration patterns in birds, and hibernation in some animals. Additionally, light pollution from human activities can disrupt natural patterns of light and dark, which can have negative effects on ecosystems and wildlife.

Overall, light is a crucial climatic factor that affects many biological and ecological processes, and its impact on the environment and the Earth’s climate cannot be overstated.

Effects of light on plants:- Light is of prime importance for plant life,as it controls their growth, physiology, morphology, reproduction, development etc.The effect of light on the plants may be summarised as follows—

1.Light is an essential factor in the formation of chlorophyll pigment in chlorophyll plants, it also has a very strong influence on the number and position of chloroplasts.The upper part of the leaf which receives full sunlight has larger number of chloroplasts that are arranged in line with the direction of light. In leaves of plants which grow under shade, chloroplasts are very few in number and are arranged at right angle to the light rays,thus increasing the surface of light absorption.

2. The opening and closing of stomata regulated by light. This in turn is related to transpiration and absorption of water.

3. The light plays as important role in maintaining the temperature of different plant organs and also controls various Enzymatic reactions.

4. In the absence of light , seedlings get etiolated in absence of light.

5. The development of flowers ,fruits and seeds is greatly affected by light intensity. Diffused light or reduced light promotes the development of vegetative structure and causes deliecacgy.

6. Very high light intensities cause solarization in plants in which all the cell contents are oxidized by atmospheric oxygen.

EFFECT OF LIGHT ON ANIMALS:– Light also affects divergent aspects of animals life .The growth,clouration of plumage or body, migration, reproduction and diapauses are affected by light in various insects,bird ,fishes, reptiles and mammals. Many animals prefer to remain in dark.The following are the important effects of light on animals.

1. Light influences pigmentation in animals .Cave animals lack skin pigments.If they are kept out of darkness for a long time,they regain skin pigmentation. The darkly pigmented skin of human inhabitants of the trophics also indicate the effect of sunlight on skin pigmentation. The synthesis of skin pigment is depend on the sunlight.

2. Majority of animals, including man, are able to see various objects only in the presence of light and the limit of visibility varies fromm animal to animal.

3. Nocturnal animals (gekos,owls etc)have their large eyes.

4. The intensity of light affects the degree of development of eyes in animals.

5. In lower animals,the speed of locomotion in influenced by light and this is k own as photokinesis.

-: TEMPERATURE:- Temperature is another important factor which regulates many chemical processes. The plants express a wide range of tolerance for temperature. Many plants are capable of surviving only within a certain range of temperature. All physical processes like growth , respiration, photosynthesis and transportation are influenced by temperature.

TEMPERATURE VARIATIONS:- The range of temperature variations in different environment are very significant. Temperature variations in aquatic environment is comparatively less than in terrestrial environment.The minimum temperature recorded in land is -700,where as the minimum temperature of water in a pond is never less than 00C and in ocean it is never below –2.50C. The temperature varies in different seasons of the year and influences greatly to various plant and animal life,which is of highly ecological significance.

THERMAL STRATIFICATION:- Thermal stratification is best illustrated in large deep perennial lakes. Studies on the vertical changes of temperature have led to the hypothetical classification of the freshwater media into three strata. The superficial layer of fresh water is constantly stirred by wind and is called epilomnion.it is the layer of warmer water and it’s temperature may rise up to 270C during Summers. The stagnant water of the bottom constitutes the hypolimnion. The hypolimnion has temperature of 50C only. In between epilimnion and hypolimnion occurs an intermediate zone called Thermocline or metalimnion ,which has rapid vertical temperature changes.

EFFECTS Of TEMPERATURE ON LIFE:- Temperature and the organisms are closely related with eachother.temperature has been found to affect the living organism in various ways. Some important effects of temperatures as follows —

1.EFFECTS ON CELL:- The minimum and maximum temperatures have lethal effects on the cells and their components. If too cold ,cell proteins may be destroyed as ice forms or as water is lost and electrolytes become concentrated in the cells; heat cogulates proteins.

2. EFFECTS ON METABOLISM:- Temperature variations have remarkable effect on the metabozof animals. Most of the metabolic processes are under enzymatic control,which inturn are influenced in temperature,upto a certain limit, brings about increased enzymatic activity, resulting in an increased rate of metabolism.

3. EFFECTS ON GROWTH:- The growth rates of different animals and plants is also influenced by temperature.for example,the adult trouts do not feed much and do not grow until the water is warmer than 100C. Likewise, in the oyster Ostraeo virginica, the length of the body increase from 1.4mm to 10.3mm when temperature is increased from 100C to 200C.

EFFECT ON REPRODUCTION:- The maturation of gonads,gametogenesis and liberation of gametes takes place at a specific temperature which varies from species to species. There are some species that breeds only in summer or in winter, some in rains, while some brees throughout the year. Thus, temperature determines the breeding seasons of most organism.

EFFECT ON SURVIVAL:- Various species of animals and plants survive at different temperatures. This range varies from 2000C to at 2720C, larva of Diptara on 550C and praying mantis at 620C. Some bacteria and algae grow in hot spring at 880C.

EFFECTS ON COLOURATION:- The size and COLOURATION of animals are subject to influence by temperature. In warm humid climates many animals like insects.Birds and mammals bear darker pigmentation than the races of some species found in cool and dry climates.

7.EFFECT ON DISTRIBUTION:- Temperature often acts an effective limiting factor in the distribution of animals and plants.As discussed earlier,each species has its own temperature requirements.for example,coralreefs which grow in a minimum temperature of 21⁰c are absent in colder regions.

8.EFFECT ON ANIMAL BEHAVIOUR:- Temperature generally influences the behavioural pattern of animals. In temperature waters the influence of temperature on the behavior of wood borers is profound .the advantage gained by certain cold blooded animals through thermotaxis or orientation towards a sources of heT are quite interesting.

EFFECT OF MOISTURE:- The different heating of the atmosphere resulting from temperature variation over the earth’s surface produced a number of ecological effects,including and trade winds and hurricanes and other stroms,but more importantly it determines the distribution of precipitation.

-:HUMIDITY:- The moisture in the air in the form of water vapour is called humidity. Atmospheric humidity is the amount of water vapour present in a unit volume of the air. It is often expressed as relative humidity. Relative humidity is the percentage of the amount of water vapours that air could at saturation at the existing temperature.

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