Researchers exploring the deep ocean have discovered hundreds of species unknown to science, including strange worms, crustaceans and other creatures that live beyond the reach of the sun’s rays.

The scientists used cameras, sonar and other equipment on five missions to study life in progressively deeper realms.

The effort to inventory the creatures of abyss was part of the Census of Marine Life, an ambitious 10-year-effort to chart the diversity, range and abundance of life in the oceans. It is an international project, involving 334 scientists from 34 countries, including Canada.

The deep sea is the Earth’s largest continuous ecosystem and largest habitat for life, says Bob Carney, a professor of oceanography at Louisiana State University.

It is dark and cold down there, about three degrees Celsius.