Scientists have discovered more than 1.35 million new species including a type of plankton that, although microscopic, is longer than any other creature on the planet. The crew of French research ship Tara spent two and a half years and 70,000 miles tracking plankton, which is a relative of jellyfish and corals and drifts on the oceans’ currents. Siphonophores are the longest type of plankton. They live in huge colonies that gang together and specialise so that they appear to be a single complex animal. The best known is the Portugese Man of War and some of the colonies can grow to over 50 metres long. During their voyage, the scientists logged 1.35 million previously unknown underwater species. Their findings will be announced on Wednesday evening at the Science Museum in London.