The abiotic factors like light, water temperature, soil etc make the climate of an area. Wherever these climatic factors are optimum, plenty of life flourishes with ease but where they are at their extremes, either at their minimum or at their maximum, life becomes miserable if not impossible. Among these least hospitable places are the deserts and the™ snow corvered polar regions of the earth. 

Ice caps of arctic and antarctic circles and peaks of high mountains are virtually incapable of supporting life because ground water is permanently frozen and not available to plant roots. Soil is almost non-existent and the temperature of the ever fast blowing air is below freezing point almost through the year. In this harsh environment it is very difficult for life to exist and hence plants and animals are present in very few numbers. It is oGY _ 155 during a short mild summer, when some ice melts, some lichens and 

| Ves grow here and there, and a few migratory birds arrive. The permanent 

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gents are a few hares, arctic foxes, polar bears and seals. They, however, 

undergone various adaptations to cope with the unfriendly environment. (develop a thick coat of hair on the skin and or a thick insulation of ynder their skin to conserve the body heat. They have broad feet and claws which help them, in walking on ice and occasionally swimming 

Another type of extreme environment, found in many parts of the ,is a desert habitat. Deserts have the most dry and harsh environment ithe earth. The rainfall here is never more than a few centimeters per whereas in some parts temperature varies between as high as 70°C yng the day time to as low as below freezing point during the night. Soil gi sand with virtually no underground water. Decomposing activity is gimal hence nutrient content of the soil is very low. Despite these yeme conditions of environment many xerophyte plants like cactus sive which has many modifications for maximum absorption and servation of water. The animals here are usually nocturnal living in gows. A familiar animal, well adapted to desert, is camel whiche « wive without food and water even for a week’s time and can cover tance of 1000 kilometers in this condition. It has many adaptive feature: tahard skin, concentrated urine and dry faeces etc. All these measures bthe animal to conserve the maximum body water. Humps, one or two, tthe store houses of reserve food. Broad and flat padded feet suit to walk ihe sand. 

As peérrule of survival of the fittest, the living things have me modified in many ways to become fit-and to get-adapted to each levery habitat even the least hospitable areas including the deserts and polar ice caps.