A census of the world's marine species shows how much we've learned about life in the ocean - including identifying around 1,000 new species of fish in the last 8 years - but also how much more there is to learn, researchers say.

Researchers spent those 8 years putting all existing databases together to compile a single definitive list known as the World Register of Marine Species or WoRMS.

WoRMS shows the total of known, identified marine species at 228,450, with more being added all the time - last year alone saw more than 1,400 previously-unknown marine creatures added to the database, or around four each day.

"Though a few relatively minor gaps remain, we consider the register now virtually complete with respect to species described throughout scientific history," says Jan Mees from the Flanders Marine Institute in Belgium, a co-chair of the WoRMS project.

"And, of course, we are constantly updating with newly-described species, revisions of taxonomy, and adding occasional species that have been overlooked."

Revisions were an important goal of the new database, researchers said; of the 419,000 species names found in the scientific literature, almost half were shown to be duplicate entries, and one species of sea snail was recorded under 113 different names.

Most of the species in the WoRMS list are animals, including more than 18,000 species of fish, around 1,800 different sea stars and 816 kinds of squid.

Non-fish marine creatures included 93 species of whales and dolphins, with two more dolphin species - in Australia and Brazil - identified just last year.

Seaweeds, kelp, other marine plants along with single-cell organisms, fungi and viruses make up the rest of the list.

The scientists behind the list say they estimate a further 10,000 or more new species are in laboratories around the world waiting for researchers to describe, identify and name them.

Despite the furious pace at which scientists are identifying new species, they say they believe it could take more than 300 years to properly identify every single species thought to inhabit the world's oceans.

"It is humbling to realize that humankind has encountered and described only a fraction of our oceanic kin, perhaps as little as 11 percent," says Mees.

"Sadly, we fear, many species will almost certainly disappear due to changing maritime conditions -- especially warming, pollution and acidification -- before we've had a chance to meet," he says.