First Marine Life Census Uncovers Unknown Species

Aug 3, 2010Updated 8 months ago

A Deep Seabed Anemone.
Scientists believe that for every marine animal they know about four more species remain undiscovered. For some groups, such as fish, scientists think they have found and named 70 percent of species. However, for life forms such as singled-celled micro-organisms and worms only about a third have been identified.

Census of Marine Life

These are some of the conclusions that have come out of the first ever Census of Marine Life (CoML). According to a CoML press release (August 2, 2010) “Scientists combined information collected over centuries with data obtained during the decade-long Census to create a roll call of species in 25 biologically representative regions - from the Antarctic through temperate and tropical seas to the Arctic.”

Vast Diversity of Ocean Life

During the ten years of the project more than 5,600 new life forms were added to the list and the complete count of species found tops 230,000.

By way of contrast, McGill University says there are 4,500 species of mammals known to science. The university adds “There are currently between 1.5 to 1.8 million named species in the world, about half of which are insects.”

Dr. Ian Poiner, CEO of the Australian Institute for Marine Science and Chair of the Census Scientific Steering Committee commented on the diversity of marine life found: “Consider that a well-informed person walking along a familiar seashore might identify 20 species or so; a fish monger perhaps 100. Even in the world’s least diverse marine regions, there are 50 to 100 times as many named species than an expert would know without resorting to field guides.”

According to a paper published in Zootaxa (“Marine Fish Diversity: History of Knowledge and Discovery,” by William Eschmeyer and colleagues, July 2, 2010) there were 16,764 known fish species in February 2010 and the number is being added to at the rate of 100 to 150 per year. The paper’s authors estimate about 5,000 fish species remain to be discovered and described.

Marine Life Inventory Continues

One of the scientists involved in the marine census is Paul Snelgrove, professor of ocean sciences at Memorial University, Newfoundland. Interviewed by Cigdem Iltan of the Globe and Mail (August 2, 2010) he said no species count has been done before now because the focus has always been on commercially viable fish: “So we spent all our energies trying to know how many cod there are, how many seals there might be. But, in fact, we now know this is not a very good approach because there are so many interactions that occur between different species.” reports (August 3, 2010) that “Australian and Japanese waters, which each feature almost 33,000 forms of life that have earned the status of ‘species’…are by far the most biodiverse. The oceans off China, the Mediterranean Sea, and the Gulf of Mexico round out the top five areas most diverse in known species.”

Inventories of marine life are still being taken in areas such as Indonesia, Madagascar, and the Arabian Sea, which have yet to report.

Arctic more Diverse than Thought

Philippe Archambault, professor of marine ecology at the University of Quebec at Rimouski told the Globe and Mail that scientists found Arctic marine life to be more diverse than expected: “We compiled 50 square metres of sediment of the sea floor in the Arctic and we found more than 1,000 species just living in the sediment of the equivalent of three Canadian kitchen floors.” And, the Arctic Ocean covers more than 14 million square kilometres.

Project Forms Baseline for Future Research

The study has been published by the open access journal PLoS ONE. It forms the baseline for measuring changes in marine life that may be the result of human activity or nature occurrences.

The lead author of the project summary is Mark Costello of the Leigh Marine Laboratory, University of Auckland, New Zealand. He says “marine species have suffered major declines - in some cases 90 percent losses - due to human activities and may be heading for extinction, as happened to many species on land.”


“What Lives in the Sea? Census of Marine Life Publishes Historic Roll Call of Species in 25 Key Ocean Areas.” Census of Marine Life press release, August 2, 2010.

“Marine Census Points to Vast Diversity.” Cigdem Iltan, Globe and Mail, August 2, 2010.

“What Lives in the Sea?”, August 3, 2010.

“Marine Fish Diversity: History of Knowledge and Discovery,” William Eschmeyer et al, Zootaxa, July 2, 2010.