femtograms C, then the global biomass of prokaryotes was reduced to 13 to 44.5 billions of tonnes of C, equal to between 2.4% and 8.1% of the carbon in plants. As of 2018, there continues to be some controversy over what the global bacterial biomass is. A census published by the PNAS in May 2018 gives for bacterial biomass ~70 billions of tonnes of carbon, equal to 15% of the whole biomass. A census by the Deep Carbon Observatory project published in December 2018 gives a smaller figure of up to 23 billion tonnes of carbon. Global biomass Estimates for the global biomass of species and higher level groups are not always consistent across the literature. The total global biomass has been estimated at about 550 billion tonnes C. Most of this biomass is found on land, with only 5 to 10 billion tonnes C found in the oceans. On land, there is about 1,000 times more plant biomass (phytomass) than animal biomass (zoomass). About 18% of this plant biomass is eaten by the land animals. However, in the ocean, the animal biomass is nearly 30 times larger than the plant biomass. Most ocean plant biomass is eaten by the ocean animals. Humans compose about 100 million tonnes of the Earth's dry biomass, domesticated animals about 700 million tonnes, earthworms over 1,100 million tonnes, and annual cereal crops about 2.3 billion tonnes. The most successful animal species, in terms of biomass, may well be Antarctic krill, Euphausia superba, with a fresh biomass approaching 500 million tonnes. As a group, the family of lanternfish are among the most populous vertebrates, with some estimates suggesting that they may have a total global biomass of 550–660 million tonnes, accounting for up to 65% of all deep-sea fish biomass. However, as a group, the small aquatic invertebrates called copepods may form the largest animal biomass on earth. A 2009 paper in Science estimates, for the first time, the total world fish biomass as somewhere between 0.8 and 2.0 billion tonnes. It has been estimated that about 1% of the global biomass is due to phytoplankton. According to a 2020 study published in Nature, human-made materials, or anthropogenic mass, outweigh all living biomass on earth, with plastic alone exceeding the mass of all land and marine animals combined. Global rate of production Net primary production is the rate at which new biomass is generated, mainly