Why Antarctic Sea Creatures Are So Different From Their Northern Counterparts

Cameron Duke of MinuteEarth explains why the underwater creatures of the Antarctic are biologically different from their northern counterparts, growing larger and living longer. This has to do with the nature of the Southern Ocean itself and a natural phenomenon known as the Antarctic CircumpolarCurrent, which cuts off underwater contact from the rest the world.

It is the largest and fastest oceancurrent on the planet, and it's also the deepest. It exists as a giant spiral of water that extendsfrom the surface to the seafloor, acting as a barrier that has prevented most SouthernOcean life from interbreeding with life fromother oceans for the last 30 million years.

The features of the current itself also help with the health of the local sea life.

But there's a benefit to being trapped behind the current -as it spirals, it churns up nutrients from the depths, which means that the SouthernOcean is full of food for all of its strange life. ...it's very salty, allowing it to get super cold without totally freezing. And that cold water allows it to hold onto lots ofdissolved oxygen - which might help animals to get bigger and age slower than they would elsewhere.