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www.GOALias.blogspot.comFig. 7.5 Feet of penguinLike polar bears, penguins are also goodswimmers. Their bodies are streamlinedand their feet have webs, making themgood swimmers (Fig. 7.5).Other animals living in the polarregions are many types of fishes, muskoxen, reindeers, foxes, seals, whales,and birds. It is to be noted that whilefish can remain under cold water forlong, birds must remain warm tosurvive. They migrate to warmer regionswhen winter sets in. They come backafter the winter is over. You knowprobably that India is one of thedestinations of many of these birds. Youmust have seen or heard about theSiberian crane that comes from Siberiato places like Bharatpur in Rajasthanand Sultanpur in Haryana, and someDo fishes and butterfliesalso migrate like birds?Fig. 7.6 Migratory birdsin their habitat/ Migratorybirds in flightDid you know?Some migratory birds travel as much as 15000 km to escape the extreme climaticconditions at home. Generally they fly high where the wind flow is helpful andthe cold conditions allow them to disperse the heat generated by their flightmuscles. But how these birds travel to the same place year after year is still amystery. It seems that these birds have a built–in sense of direction and know inwhich direction to travel. Some birds probably use landmarks to guide them. Manybirds may be guided by the sun during the day and stars at night. There is someevidence that birds may use the magnetic field of the earth to find direction. Andit is not only birds that migrate; mammals, many types of fish and insects arealso known to migrate seasonally in search of more hospitable climates.74SCIENCE