Rosette used to collect seawater samples during a scientific cruise in the South Pacific Ocean. Duringthe austral summer,the amount of chlorophyllais so low thatthe water becomesdeepblue,almostpurple. (Photo : Joséphine Ras)
Diatoms - Life in glass houses Champions of photosynthesis, these unicellular organisms appeared at the time of dinosaurs.They produce a quarter of the oxygen we breathe.