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Give reason for the following
i) Kangaroo rat can survive in the absence of an external source of water.
ii) Small animals are rarely found in the polar regions.

Last updated date: 23rd Jun 2024
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Hint: In the arid areas of the West and South-West of the USA, kangaroo rats are found. The polar regions of the world, also called the refrigerated regions, are the regions around the Earth's geographical poles, found in the polar circles. They reside in the desert and grasslands and prefer heavier terrain that supports their burrow and tunnel systems.

Complete answer: i)The kangaroo rat, a rodent from the south-west of the USA, can live all his life remarkably without ever drinking a single drop of water. The kangaroo rat, known as such, because it has big powerful back legs that allow it to sauté until 3 metres (9 ft) at once so as not to become predatory, mainly survives on seeds and beans which have high water content. In addition, the average lifespan for kangaroo rats is ten years in the wild, and this particular rodent can go without water for a whole decade while a camel can go for months. This is because they are the largest urinators in existence. Yeah, the kidneys of a kangaroo rat are so powerful and their pee so focussed that they live their entire existence without water. The kangaroo rat is able to satisfy all water demands by its inner fat oxidation, with water as a by-product, when it is not an external source of water. It can also concentrate its urine to extract excretory materials, using a minimum volume of water.
ii) In cold environments, birds and mammals achieve greater scale than in warm areas, the temperature influences the absolute size of a specific species and the relative proportion of different body parts. In cold regions, however, poikilotherms are smaller. This is the law of Bargeman. This is because small animals have a greater area compared to their volume, so they lose their body heat very easily if they are cold. The reduced surface area to volume is suitable in cold weather. Small animals have a broader volume surface area and they appear to lose heat easily when outside is cold. We (humans) have to invest a lot of power in metabolism to produce body heat. So, in polar regions, small animals are seldom found.

Note: As worldwide attention is paid to the global environment, polar regions have been found to respond acutely to climate and temperature fluctuations. As ice appears to reflect and absorb solar radiation, it can be affected by melting in the polar areas, both atmospheric and occidental.