That waters that surround Antarctica are trapped in place by the Antarctic Circumpolar Current, which encircles that continent and keep marine life inside isolated from the Atlantic, Pacific, and Indian Oceans. Marine life in those waters are unable to interbreed with outsiders and have developed evolutionary advantages particular to this environment. These adaptations include fish with translucent blood and the ability to absorb oxygen through their skin, starfish and sponges with extreme longevity, and, in general, colossal size in comparison to their counterparts elsewhere on the planet.
Minute Earth, a YouTube channel that educates people about science, worked with the National Science Foundation and the marine ecology-focused Bik Lab at the University of Georgia to create this video.
-via Laughing Squid