About 226,000 marine species have been identified and described so far. These are but a small portion of the total: researchers estimate that the ocean may be home to 700,000 marine species, and likely not more than a million, according to a study published online in Current Biology today and coordinated by Ward Appeltans of the Intergovernmental Oceanographic Commission of UNESCO. The study draws its conclusions from the World Register of Marine Species (WoRMS).
Well-known marine animals, such as whales or dolphins represent a tiny fraction of marine biodiversity. Fish species only represent two to three per cent of all living things in the ocean. While many species have yet to be discovered, the knowledge base is expanding faster than ever before and researchers estimate that the vast majority of unknown species may be found and documented by the end of this century.
More marine species have been discovered in the past decade than ever before with an average of 2,000 discoveries per year. The new species discovery rate is still increasing for species in the Ocean, while this is no longer the case on Land. The momentum is due in part to greater taxonomy efforts, a growing number of researchers involved in describing new species, and new technologies allowing them to access previously unexplored areas (including improved diving gear and remotely operated submersible vehicles).
Roughly 150 new species of marine fish are described each year. Experts estimate that, at this rate, it would take another 30 years to describe the 5,000 species of marine fish that remain unknown today. Large animals are still discovered today, for instance 780 crab species, 29 lobster species, 286 shrimp species and 1,565 types of fish were new to science between 1999 and 2008. Researchers speculate that 2 to 8 new cetacean species and almost 10 marine reptile species (like sea snakes) remain to be discovered.
However, the unknown species are composed disproportionately of groups of macroinvertebrates, with tens of thousands of species of smaller crustaceans, molluscs (snails) worms and sponges awaiting discovery. In many cases (roughly 65,000 unknown species), samples have been collected but have not yet been documented or described.
‘Ocean life represents older evolutionary lineages then life found on land. Evaluating the total number of species is important because it gives us an idea of what we know and how much we don’t yet know of life in the Ocean. It helps us better understand and assess each species’ role and function in the ecosystem’, says Ward Appeltans, coordinator of the Ocean Biogeographic Information System (OBIS) of the Intergovernmental Oceanographic Commission of UNESCO. ‘This study is the result of an unprecedented global collaborative effort involving many leading taxonomists. It will set standards and serve as a reference for future biodiversity studies and conservation efforts and will serve scientists, students, policy makers and anyone who is interested in the diversity of life on our planet’.
The World Register of Marine Species (WoRMS) is an open-access, online database created in 2007 with the participation of 146 institutions in 32 countries. It is based on the model of the European register of Marine Species and hosted by the Flanders Marine institute in Belgium.
The Ocean Biogeographic Information System (OBIS) is an open, online database and tool on the biodiversity, geographic distribution and abundance of marine life. OBIS contributes to the protection of marine ecosystems by helping to identify areas under threat and increasing the knowledge base to better manage and protect our ocean.
Media contact: Agnès Bardon, UNESCO Press Service : +33 (0) 1 45 68 17 64, a.bardon(at)unesco.org