Krill
Videos
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
Zooplankton
Videos
Zooplankton are the animal component of the planktonic community, having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers.
Zooplankton sample including several species of copepods (1–5), gastropod larva (6) doliolids (7), fish eggs (8), and decapod larva (9) (Photo by Iole Di Capua)
Upper left: Biogeochemical models Right: Ecosystem models Lower left: Size-spectra models These models also have temporal and spatial components.
Like diatoms, radiolarians come in many shapes
Also like diatoms, radiolarian shells are usually made of silicate