Number of marine species
According to the World Register of Marine Species, WoRMS, the total number of marine species known to us is about 240,000 species (2021 census). However, it is estimated that there are 1.4 -1.6 million marine species on earth (Bouchet, 2006.). Another, more recent estimate is about a half lower (0.7-1 million (Appeltans et al., 2012). The reason for the huge range in the estimated number of species is the lack of information on the diversity of some of the smaller organisms on Earth. For example, in the ocean, there is a plenty of information on marine mammals (seals, whales, dolphins, porpoises) and fish, while only recently are scientists beginning to understand the extreme diversity present in micro-organisms such as bacteria and phytoplankton (i.e. the plants of the sea). In Europe alone it is estimated that there are 41,000 - 56,000 species present (5,000 - 20,000 have yet to be identified!). There are 1,000 - 1,500 new marine species identifed each year!
Census of Marine Life
The Census of Marine Life was an international project spanning 10 years that recorded the diversity, distribution, and abundance of life in the ocean. More than 2,700 scientists from 80 nations contributed to the Census. The results of their research, which included 540 marine expeditions, were reported at The Royal Society, London, in October 2010.
During the Census, scientists found and formally described more than 1,200 new marine species, with thousands more awaiting formal descriptions; discovered and mapped areas in the ocean where marine species congregate; and documented long-term and widespread declines in marine life as well as species resilience and recovery.
- Bouchet, P. (2006). The magnitude of marine biodiversity, in: Duarte, C. (Ed.) (2006). The exploration of marine biodiversity: scientific and technological challenges. pp. 31-62
- Appeltans, W. et al. 2012. The Magnitude of Global Marine Species Diversity. Current Biology 22: 2189-2202