Gruber's team of researchers work day and night. In this episode they record a shark's vital statistics while it's in a state of tonic immobility. Before releasing it, they take a DNA sample. Enjoy!

At times, Doc Gruber's research requires the team to dive right into shark-infested waters! Their line of work certainly isn't for the faint of heart! Enjoy.

Nathalie and Jim get up close and personal with tiger and lemon sharks, trying to get the best footage while taking care not to disturb or excite the dangerous animals.

The team's divers conclude their filming and come back to the surface unharmed. We learn more about current developments in the prevention of shark attacks.

In this episode, Doc Gruber and a colleague are testing a shark repellent. If effective, it could help save the lives of divers, swimmers and surfers all over the world.

Here's some more stunning underwater footage. This time it's hammerhead sharks and stingrays, a wahoo and some striped eels, all filmed near the Cocos Island in the Caribbean. Take a look!

Samuel Gruber's team films white-tipped sharks and barracuda feeding at night off Cocos Island. Enjoy!

Fascinating footage, our journey begins in Alaska's Katmai National Park, both inhospitable and beautiful. We observe brown bears as they hunt salmon, track the rare glacier bear, and then continue south to British Columbia on our hunt for the rare Kermode bear, also called ghost bear or spirit bear.

Our journey begins in Alaska's Katmai National Park, both inhospitable and beautiful. We observe brown bears as they hunt salmon, we track the rare glacier bear, and then we continue south to British Columbia on our hunt for the rare Kermode bear, also called ghost bear or spirit bear.

More stunning footage from Alaska shows, up close and personal, the brown bears in action - hunting for salmon and caring for their young. Enjoy!

Observe more stunning footage from Alaska of the bald eagle and the black bear. And finally catch a first glimpse of the rare glacier bear. Enjoy!

In summer, mother bears and their young cubs can be spotted on the plains near Hallo Bay in Alaska's Katmai National Park.

Young black bears need to be careful when encountering the North American porcupine. Enjoy more footage from Alaska and Princess Royal Island in British Columbia, where young raccoons are also out and about.

When you listen to music, multiple areas of your brain become engaged and active. But when you actually play an instrument, that activity becomes more like a full-body brain workout. What's going on? Anita Collins explains the fireworks that go off in musicians' brains when they play, and examines some of the long-term positive effects of this mental workout.

Catch glimpses of sockeye salmon, also called red salmon, as they make their way upstream in a migration known as the "red flood." Also included is footage of dippers, which are some of the only songbirds that search for food on the bottom of a body of water.