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
Mesopelagic zone
Videos
The mesopelagic zone, also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins at the depth where only 1% of incident light reaches and ends where there is no light; the depths of this zone are between approximately 200 to 1,000 meters below the ocean surface.
Sediment trap sample, Thermaikos Gulf, Greece, 2000. Stereoscopic image of the collected material above 63-μm pore size net. Calcareous shells and skeletons of planktonic organisms can be identified.
Sonar data. The green layer in the water column is the deep scattering layer of diel vertically migrating mesopelagic zooplankton and fish.
Illustration by Charles Frederick Holder of various bioluminescent fish that live in the mesopelagic zone
Helmet jellyfish, Periphylla periphylla