The Global Ocean

The Global Ocean is set in the only ocean in the world, 200,000,000 years into the future. At this point in the future, there are no mammals, birds, reptiles or amphibians. The episode focusses on four species.
Rainbow Squid - although some cephalopods took to the land, this one did not. It is a massive squid which changes colour to hide.
Ocean Flish - descendants of common fish like cod which have evolved to breathe out of water and have developed wings.
Sharkopath - a descendant of sharks that have bio-luminescent patches on their sides to communicate with one another.
Silverswimmer - descendants of plankton that have grown in size and evolved to fill the roles that fish previously held. There are many different species and they have different ways of life - some are predators, some are prey and some are scavengers.
Since all the land is joined together, much like Pangea, there is only one ocean now as well. Some views from space show the Earth as just a blue circle now. This episode shows how weird things have got and, no matter what happens, life will continue to thrive in the oceans