Up to three-quarters of ocean creatures still to be discovered

Up to three-quarters of the world’s marine animals and plants are yet to be described by scientists, according to the first official register of what lives in the oceans.

Researchers estimate that the total number of species in the seas is between 700,000 to 1 million, but only 226,000 have been formally identified.

In total, between 482,000 and 741,000 marine species are yet to be discovered, though an estimated 58,000 to 72,000 are thought to have been collected as samples and are awaiting analysis.

However, such is the rate at which they are being identified, with 20,000 being discovered in the last ten years – more than in any other decade – they expect the majority to be found by the end of the century.

“Currently, between one-third and two-thirds of marine species may be undescribed, and previous estimates of there being well over one million marine species appear highly unlikely,” an international research team reported in the journal Current Biology.

“More species than ever before are being described annually by an increasing number of authors. If the current trend continues, most species will be discovered this century.”

From 1999 to 2008, there were 780 new species of crabs discovered, 29 lobsters, 286 shrimps, 1,565 fish, 4 sea snakes, and three ceteceans.

The findings were made as researchers compiled the World Register of Marine Species (WoRMS), an online database which has been created by 270 marine taxonomists from 146 institutions in 32 countries.

Of 400,000 marine species that have been named in scientific literature, 170,000 were discounted as already appeared. “That means that on average, for every five species described as new to science, at least two had already been described,” they said. They noted that 87 whale and dolphins were known by 1,271 names.

Scuba diving, submersibles and other technological advances, especially in deep waters, are among the main reasons for the recent high rate of discoveries as they have allowed “previously unexplored habitats” such as cold seeps and hydrothermal vents to be sampled and observed.

But often discoveries are made in areas that already well known: “The use of submersibles and deep diving resulted in the discovery of 30 new fish species around even such a highly studied area as the Galapagos Islands.”

Most new discoveries in the future are expected to be of small creatures such as crustaceans, molluscs, worms and sponges but as the recent identification of the spade-toothed beaked whale illustrated, there are some large animals still to be found.

Ward Appeltans of the Intergovernmental Oceanographic Commission (IOC) of UNESCO, said of WoRMS: "For the first time, we can provide a very detailed overview of species richness, partitioned among all major marine groups. It is the state of the art of what we know—and perhaps do not know—about life in the ocean.”