A shift of power is taking place at the top of the world. The polar bear, once king of the North, needs ice to stalk its prey. Killer whales, or orca, on the other hand, are unable to hunt in an ocean locked in ice. As Arctic ice increasingly disappears, the tables have turned. Polar bears are struggling to survive while the now open ocean provides bountiful new hunting grounds for the whales.

In 2000 in the jungles of Panama, a young journalist, named Ana, has a chance encounter with a tiny orphaned sloth, which she names Velcro. For nearly two years, the pair is inseparable until finally Ana travels up a remote river to reintroduce Velcro back to the wild. This is the story Ana’s return to Central and South America to see how much has changed since Velcro came into her life.

Christy Fromel, a member of the loosely organized "Citizen Sloth Patrol", searches for sloths on a road not far from the Panama Canal. The concerned citizens who make up the patrol rescue sloths crossing dangerous roads in search of a new home.

Journalist Ana Salceda searches for pygmy three-toed sloths (Bradypus pygmaeus) on Isla Escudo de Veraguas, a small island off the coast of Panama. What she finds exceeds her expectations--a sloth mother with a baby in tow.

Mudskippers, a type of fish that can breathe air, scour the beach on the coast of Japan looking for their next meal.

Three-toed sloths are some of the slowest and seemingly laziest creatures in the world. Instead of evolving to eat more, they evolved to do less.

Alongside the fastest, strongest, smartest animals are nature’s misfits, odd, bizarre and unlikely creatures that at first glance seem ill-equipped for survival. Left at the starting line in the race for life, these are the apparent losers in the story of evolution, yet somehow they manage to cling to life and in some cases even thrive.

For nearly a year, 50 animatronic cameras disguised as realistic life-size penguins, eggs and rocks infiltrate penguin colonies to record the tough challenges penguins face from the moment they emerge from the sea to raising their chicks and finally returning to the water.

For nearly a year, 50 animatronic cameras disguised as realistic life-size penguins, eggs and rocks infiltrate penguin colonies to record the tough challenges penguins face from the moment they emerge from the sea to raising their chicks and finally returning to the water.

For nearly a year, 50 animatronic cameras disguised as realistic life-size penguins, eggs and rocks infiltrate penguin colonies to record the tough challenges penguins face from the moment they emerge from the sea to raising their chicks and finally returning to the water.

Rockhopper penguins brave crashing waves to reach their breeding grounds in the Falkland Islands.

Emperor dads stand watch as penguin hatchlings peck their way free.

Catch a sneak peek of the upcoming season of Nature. New episodes include "Big Thinkers of the Forest", "Animal Misfits", "A Sloth Named Velcro" and "The Animal Home Show".

The African bullfrog (Pyxicephalus adspersus) is the biggest frog in Africa and very aggressive. But in spite of that, it’s a devoted father. Bullfrogs spawn in little pools around the margins of larger ponds and after mating is over one male stays to keep watch. If the pool dries up the dutiful dad digs a channel to a new water source.

The male Panamanian Golden Frog (Atelopus zeteki) has a subtle ways of attracting a females--it waves. This friendly gesture can attract the unwanted attention of a rival male, which often ends in a wrestling match.

Sir David Attenborough takes us on a journey through the weird and wonderful world of frogs, shedding new light on these charismatic, colorful and frequently bizarre little animals through first-hand stories, the latest science, and cutting-edge technology. Frogs from around the world are used to demonstrate the wide variety of frog anatomy, appearance and behavior.

As the only creatures on earth to breed in the Antarctic winter, their survival, as well as those of their chicks, is put in jeopardy when the temperature falls to 40 below. So, instinctively, emperor penguins all converge on the same central point and begin to form a huddle. As those on the outside take the brunt of the cold, those on the inside take tiny steps that move the huddle in waves.

In Sonora, Mexico, thousands of Gulf Grunion fish act on a seemingly suicidal desire to breed out of water. The female grunion deposit eggs in the sand as far from aquatic predators as possible. The eggs remain buried in the wet sand and hatch in about 10 days, at which point the young grunion make their way back into the water.

The seasonal movement of billions of sardines along the coast of South Africa, the greatest fish migration on the planet, includes a stunning example of collective thinking to throw off predators. Synchronous movement by the sardines relies on a pressure sense that runs along their bodies to detect the movements of their nearest neighbors.

Get a look at some of the planet’s great gatherings, creatures that come together in inconceivable numbers — sometimes in millions, billions, even trillions. In the process, a kind of super-organism is created in which individual intelligence is superseded by a collective consciousness that shares information and moves with a single purpose for the benefit of all.