Water world

A few winters ago, I spent a week in one of the smaller islands of the Andaman archipelago. Some mornings I could walk most of the way around the island, at the edge where land and sea meet. The green wall of trees on one side would loom over the mysterious blue depths on the other. Our world is a water world; almost three quarters of its surface is ocean, over half the life on earth is oceanic. What do we know about it?

A recent read (partly hidden behind a paywall) overturned everything that I though I knew about the earth. It seems that plants make up less than 10% of the biomass of the oceans (they make up 95% of the biomass on land). The waters of our world are dominated by animals, bacteria, and complex single-celled creatures collectively called protists. These three groups make up 80% of the biomass of the oceans (on land, these groups make up 2% of the biomass). In the oceans fast growing primary producers make up about 15% of the biomass, whereas consumers, with a slow lifecycle, make up the rest. There are two different worlds sharing this planet of ours!