In the grasslands, animals endure freezes, fires, floods, and droughts; bull elephants clash in mating battles; cheetahs and gazelles engage in a predator-and-prey dance in the Kenyan savanna; bison battle a blizzard while being pursued by wolves.

Deserts are getting even hotter, drier and bigger, yet a host of remarkable animals still survive in the harshest of conditions, including cunning hyenas, pint-sized meerkats and sand-dwelling spiders.