Hatchling turtle from "The Triumph of Life"

Since 1982, Nature has attempted to capture the full experience of life on our planet--from birth and perilous baby steps to the fight against predators and the struggle to reproduce. Now, scenes from many of Nature 's most memorable programs tell the epic story of life in the wild on "The Best of Nature --25 Years , " airing Sunday, Jan. 14 at 8/7 p.m. CT on KET2 and Saturday, Jan. 20 at 9/8 p.m. CT on KET1. 20/20 correspondent Lynn Sherr hosts the anniversary special.

For some animals, life's perils begin immediately. Hatchling sea turtles' first steps toward the water are threatened by such deadly predators as vultures and crabs in scenes from "Triumph of Life . " And in the Arctic, barnacle goslings, born in nests atop steep cliffs, must survive a freefall to the rocks below in order to reach the safety of a river in "Kingdom of the Ice Bear . "

The daily struggle for survival is played out in highlights from "The Reptiles , " where crocodiles take down gazelles attempting a river crossing, and "Serengeti Stories , " in which a mother wildebeest desperately defends her young calf against attacks by wild dogs.

Reproduction is the next imperative for wildlife. This segment includes moments from "Great White Bear , " in which a mother polar bear in the high Arctic nurtures her newborn cub beneath the northern lights.

Finally, "The Best of Nature --25 Years" looks at the enduring bonds between animals. After 25 years apart, the poignant reunion of elephants Shirley and Jenny, from "The Urban Elephant , " shows that they are social creatures for whom companionship is vital.

Other highlights come from "Cloud: Wild Stallion of the Rockies , " "India: Land of the Tiger , " "Silent Roar: Searching for the Snow Leopard" and "Katrina's Animal Rescue , " among others.

Nature is produced by WNET/New York.