On the trail of tiger sharks in the Pacific, Will Smith explores the power of smell. Sharks have a sense of smell that's hundreds of times more potent and accurate than that of humans. An enormous part of their brain is dedicated to smelling, to finding their way through the vast expanse of the ocean.

We love nature and all its glorious diversity. Some creatures we admire for their deadly beauty, others because they are cute, but for some it's hard to figure out exactly why we like them so much, perhaps it's a quirk. How do you decide nature's weirdest animal? Is it the sloth that hangs upside down and moves so slowly that moss grows in its fur? Is it a sea pen that sits rooted to the seabed in endless darkness and emitting its own glow? Could it be carnivorous snails that leave the ocean to digest dead creatures on the beach, finches that drink blood, or the tarantula that keeps a frog as it's pet. But with nature's endless variety, which is the weirdest? We can't decide. Can you?

In the third episode, Will Smith crosses the Serengeti to catch one of the greatest events of nature. "An image, one and a half million wildebeests on the plains of Africa in the most dramatic migration on Earth, has stayed with me since around thirty years ago I picked up a National Geographic Magazine and saw it. And finally, I'm here to see it."

In changing seas and oceans, cephalopods like the cuttlefish and the giant Pacific octopus must rely on their remarkable intelligence to survive. Their alien appearance comes with astonishing resources, independence, and invention. And there's still so much to learn about these rarely seen legends of the deep.

It's not all about the pouches. These mammalian misfits are full of surprises, from flamboyant kangaroo showdowns to rattling koala mating calls. They might seem a bit bizarre but don't underestimate them. With unexpected superpowers and amazing adaptability, they have conquered a continent.

Be it foxes on city streets or wolves on the tundra, canines rely on sharp senses, athleticism and fierce determination to punch above their weight. But the real secret of their success is much more surprising. It's a story of their intimate side. It's what makes every dog, from pet pooch to wild dogs, one of the family.