Krill
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Krill (Euphausiids), are small and exclusively marine crustaceans of the order Euphausiacea, found in all the world's oceans. The name "krill" comes from the Norwegian word krill, meaning "small fry of fish", which is also often attributed to species of fish.
Krill anatomy explained, using Euphausia superba as a model
The gills of krill are externally visible
A nauplius of Euphausia pacifica hatching, emerging backwards from the egg
Biomass (ecology)
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Biomass is the mass of living biological organisms in a given area or ecosystem at a given time. Biomass can refer to species biomass, which is the mass of one or more species, or to community biomass, which is the mass of all species in the community. It can include microorganisms, plants or animals. The mass can be expressed as the average mass per unit area, or as the total mass in the community.
The total global live biomass has been estimated at about 550 billion tonnes carbon, most of which is found in forests.
Shallow aquatic environments, such as wetlands, estuaries and coral reefs, can be as productive as forests, generating similar amounts of new biomass each year on a given area.
Relative terrestrial biomasses of vertebrates versus arthropods
Prochlorococcus, an influential bacterium