Vast numbers of ocean species are unknown

By AAP with AG staff 3 January 2013
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Somewhere between one- and two-thirds of all species in the world’s oceans are still unknown to science, says study.

THE WORLD’S OCEANS are teeming with as many as 1 million different species – from microscopic plankton to monster whales – and a third or more of them are still unknown to science, according to the first full-scale register of the diversity of the seas.

The census of all the ocean’s plants and animals by hundreds of ocean scientists from around the world is just an estimate, however the species-by-species count is crucial for understanding the biodiversity of all the oceans and for protecting their future in a swiftly changing environment, says Professor Stephen Palumbi, director of Stanford University’s Hopkins Marine Station in Pacific Grove, California.

“It’s the best job ever of tallying everything we know – and what we don’t know – about life in the oceans today,” Stephen says. “It’s the first time anyone’s done this kind of dirty work that’s so important with the world’s oceans facing a biodiversity crisis.”

Click here to see a gallery of weird ocean life

Marine species in crisis

The biodiversity crisis has many causes, including overfishing, widespread damage to coastal environments, and increasing acidification of ocean waters as carbon dioxide levels rise.

The inventory, which is still being compiled, is called the World Register of Marine Species (WoRMS). It is being amassed by a unique collaboration among marine scientists – 270 experts from 146 institutions in 32 countries, including Australia – whose specialised research is being gathered into a single database.

“For the first time, we can provide a very detailed overview of species richness, partitioned among all the marine groups,” says Ward Appeltans, a biologist at UNESCO’s International Oceanographic Commission office in Ostend, Belgium, who led the effort. “It is the state of the art of what we know – and perhaps do not know – about life in the ocean.”

Mysterious underwater creatures

According to the census, somewhere between 482,000 and 741,000 species have yet to be collected by sampling efforts.

Approximately 226,000 non-bacterial marine species have been described, but up to 170,000 of these could be species that were accidentally named twice. Somewhere between 58,000 and 72,000 species are already in museum collections but have not yet been officially named and described, the survey reports.

One contributor is Professor Rich Mooi, curator of invertebrate zoology at the California Academy of Sciences, who studies the life and death of organisms like sea urchins, sea stars and sea cucumbers, known as echinoderms.

Rich, who collects these animals from the Philippines to Antarctica, estimates they number up to 8000 separate living species, with up to 15,000 long gone and in the fossil record. “You can’t understand the evolution of all of today’s organisms without comparing them as they are now with how they were long, long ago,” he says.

“All those species have figured out how to live in the world that’s been changing for millions of years,” Stephen says. “So if you want to know how they’ve lived through climate changes in the past, they could have lessons for us.”

Click here to see a gallery of weird ocean life

Cryptic diversity of ocean life

To illustrate the problems of identifying individual species in a census like this, Stephen, a marine biologist, recalled his own difficulties as a specialist in the life of corals. He studied the forms of what scientists had long thought were two coral species living in habitats spread across the Pacific, from Samoa to Zanzibar.

The samples of each coral species looked alike, but when he and his colleague Jason Ladner analysed the genes of those corals, they found that the two were actually six distinct species. The discovery was an example of what scientists call “cryptic diversity,” he says.

A bigger puzzle for the census takers was estimating the number of marine species that are still unknown to science. They examined hundreds of collections in museums around the world, and from the number of species that remain unidentified there, they calculated that about one-third of the ocean’s species are yet to be discovered.

The complete results of the continuing inventory are now listed in an open-access database at

Their findings were reported in the journal Current Biology late in 2012.