Known to some as "unicorns of the sea," this pod of male narwhals lift their nearly eight-foot-long ivory tusks out of the water and take a deep breath before disappearing back under the ice to gorge on polar cod. Plankton grows on the underside of the sea ice, amphipods feed on the plankton, cod feed on the amphipods, and narwhals feed on the cod – so goes the circle of life in the Arctic.