The wondrous (tiny) world of plankton.
Phytoplankton (small plant-like cells) are producing half of all oxygen on earth by photosynthesis, like plants and trees do on land. Zooplankton are forming the base of the food chain of aquatic life. Plankton are also playing an important part in the global carbon cycle. The plankton are threatened by climate change, global warming and acidification of the oceans.