The leopard seal is one of the largest seal species and an apex predator. So, what could take one on? Another leopard seal! With the help of "crittercams," scientists are able to see the rivalries that go on under the ocean's surface–and they aren't always the classic battle of predator vs. prey. Join Wildlife Biologist and National Geographic Explorer Douglas Krause as he learns more about these formidable predators in the threatened Antarctic ecosystem.