Makes me think of the Motile Islands in Dan Simmons' fiction
Symbiotic islands of floating creatures guided through the oceans by dolphins.
They would also sail in the winds, seeking the best feeding and sun.
The planet was so beautiful it became a resort and was overbuilt, killing the islands.
I think Nick has it pretty much right: too much crust and too little "rapid" tectonics and you have a dead planet.
I have been torying with the axis tilt of a planet and what that might imply for life. An axis change could be profound.
Ed