Several boats converge near the largest of the Farallon Islands when killer whales are spotted. But what they think is a young killer whale turns out to be a great white shark.

Orcas are at the top of the food chain, but it is unprecedented that they would go after a great white shark. From the boat, whale watchers and experts alike are shocked by what they see.

Why would a killer whale go after a great white shark? Enter Alisa Schulman-Janiger, a biologist who is very familiar with the different families of killer whales off the coast of California.

So if an orca attacking a shark is so rare, how do they usually behave? In this segment, we learn about how orcas around the world live and hunt.

Some orcas do prey on sharks, but how do they do it? Researchers also have to catch sharks occasionally, and there is a particular technique that they use.

The phenomenon of tonic immobility helps researchers study sharks, but does it also help orcas hunt and kill them?

Here we see a simulation of how the attack happened, and find out what effect it had on the population of great white sharks around the Farallon Islands.

How do sharks communicate? Particularly, how would the sharks around the Farallones all know exactly when to evacuate? Scientists who are working on "shark repellent" may have an explanation.

Although no one will ever be completely certain why it occurred, many things have been learned about both species from the attack.

National Geographic filmed South African penguins in their natural habitat. One penguin turns to crime in order to furnish the nest and keep his mate happy.

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.