Drawing on three years of work by more than 300 scientists, the Census of Marine Life has released the first comprehensive estimate of the total number of species in the ocean. The census gives a better picture of Earth’s biodiversity, since 20 percent to 50 percent of all living things are aquatic. Researchers have already entered more than 20,000 organisms into the database, and they expect to add hundreds of newly found ones each year. To manage all the information, the census splits the ocean into six realms, determined by geography and climate. Team scientists then estimate how many forms of life have yet to be discovered in each realm based on how well it has been studied and how many species have been discovered there so far. On the deep ocean floor, for instance, more than 80 percent of the species being found are unknown. “The limiting feature of the discovery process will be descriptions,” says Ronald O’dor, the census’s senior scientist. “We need new people with the old taxonomic skills or we need alternate technologies.”