Since the Antarctic Treaty governs events and geographies south of 60 degrees South Latitude, all animals within those boundaries are protected by the tenants of the treaty.
The treaty, however,...
That would probably be the orca, a member of the dolphin family. Though leopard seals are also excellent hunters. The orca (killer whale) is the top of the food chain. They even eat blue whales...
The Arctic: Arctic Foxes, Arctic Hares, Polar Bears. The Antarctic: Penguins.There are many animals and birds that live in the Arctic and Antarctic regions. See the two related questions.
I recommend you rent and watch the movie "March of the Penguins." Antarctic animals either have thick skin/blubber to insulate them from the cold or, in penguins' case, huddle together in a huge...