Red tide is back in Algoa Bay with a vengeance. Strong orange red patches have been reported all over the bay and in adjacent areas. The dinoflagellate species responsible is called Noctiluca miliaris and is not the same species that was responsible for the red tides at the beginning of 2014. At the beginning of this year Lingulodinium polyedrum was the guilty party. These two species are very different Lingulodinium is small (about 20 thousandths of a mm in size) while Noctiluca is about half a mm in size and visible to the naked eye. If you collect some of the water from the red tide and let is stand for a bit you will notice the dinoflagellates collecting at the water surface. You will also notice that you can see them with the naked eye. Lingulodinium grows by absorbing light energy and fixing carbon dioxide to make the organic compounds that it incorporates into its body in a process called photosynthesis. Noctiluca cannot photosynthesise and behaves a bit like an animal (although it is not) by ingesting other photosynthetic microalgae called diatoms. It uses these tiny organisms as food to fuel their growth. The orange red colour of the Noctiluca comes from the pigments in the diatoms that they eat. Both Lingulodinium and Noctiluca bioluminesce and produce spectacular shows at night in the breaking waves.