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plankton torpedo
planktivores animals feeding on plankton.
plankton floating organisms of many different phyla, living in the pelagic of the
sea or in freshwater, to a large extent subjected to water movements. (Functional) classification is based on trophic level, size and distribution. Autotrophs
(primary producers) constitute phytoplankton, heterotrophs (consumers) bacterioplankton and zooplankton. A differentiation in size classes is related to
retention by different mesh sizes of plankton nets and filters used, which, however, have no standard dimensions: picoplankton < 2 jlm; nanoplankton 2-20 jlm;
microplankton 20-200 jlm; mesoplankton 0.2-2 mm; macroplankton 2-20 mm; megaplankton > 20 mm. In marine plankton the more coastal organisms are
termed neritic, in contrast to oceanic plankton. Related to depth of occurrence is a differentiation in epipelagic to bathypelagic plankton. Holoplankton
has a completely pelagic life cycle, while meroplankton consists of temporarily
pelagic stages of otherwise sessile and benthic organisms.
Plankton Expedition (1899) Germany's first big oceanographic expedition, studied the northern Atlantic ocean on board of the National under direction of
Victor Hensen, who had developed methods to study the drifting organisms
(named plankton by Hensen) for the first time quantitatively. Hensen's main
goal was to study the productivity of the ocean as a framework for maintaining or improving fisheries. The productivity of the fisheries must
depend on plankton abundance. Fine-meshed nets hauled vertically from
200 m depth to the surface were used to give an estimate of the quantity of
plankton. Under its staff were a.o. Otto Krummel (physical oceanographer),
Karl Brandt and Friedrich Dahl (zoologists) and Franz Schutt (botanist).
Against theory and expectations, the warm tropical Atlantic had much less
plankton than the cold northern seas. Ernst Haeckel was one of the most
fervent condemners of Hensen's results: as on land the tropics must be rich
and the north barren, Haeckel did not understand Hensen's quantitative
approach (how such plankton counting could be carried through without
the ruin of mind and body Haeckel could not conceive). Hensen's student H.
Lohmann also criticized the results as he found abundant nanoplankton that
escaped the nets; however, nanoplankton collected by centrifuging water
samples followed the net plankton distribution observed during the plankton expedition. Superb lithographs illustrate the large, important, and beautiful reports which were completed in 1926.
plankton torpedo plankton net in a torpedo-shaped housing, to be towed behind
a (fast-)moving ship. The basic function of the housing, with a narrow
entrance in front of a funnel-shaped widening, is to reduce the inflow, and,
by the generated underpressure behind the funnel, to increase the flow
through the plankton gauze, which is necessary when fast (up to 6 knots)
hauls are made.
plankton torpedo
planktivores animals feeding on plankton.
plankton floating organisms of many different phyla, living in the pelagic of the
sea or in freshwater, to a large extent subjected to water movements. (Functional) classification is based on trophic level, size and distribution. Autotrophs
(primary producers) constitute phytoplankton, heterotrophs (consumers) bacterioplankton and zooplankton. A differentiation in size classes is related to
retention by different mesh sizes of plankton nets and filters used, which, however, have no standard dimensions: picoplankton < 2 jlm; nanoplankton 2-20 jlm;
microplankton 20-200 jlm; mesoplankton 0.2-2 mm; macroplankton 2-20 mm; megaplankton > 20 mm. In marine plankton the more coastal organisms are
termed neritic, in contrast to oceanic plankton. Related to depth of occurrence is a differentiation in epipelagic to bathypelagic plankton. Holoplankton
has a completely pelagic life cycle, while meroplankton consists of temporarily
pelagic stages of otherwise sessile and benthic organisms.
Plankton Expedition (1899) Germany's first big oceanographic expedition, studied the northern Atlantic ocean on board of the National under direction of
Victor Hensen, who had developed methods to study the drifting organisms
(named plankton by Hensen) for the first time quantitatively. Hensen's main
goal was to study the productivity of the ocean as a framework for maintaining or improving fisheries. The productivity of the fisheries must
depend on plankton abundance. Fine-meshed nets hauled vertically from
200 m depth to the surface were used to give an estimate of the quantity of
plankton. Under its staff were a.o. Otto Krummel (physical oceanographer),
Karl Brandt and Friedrich Dahl (zoologists) and Franz Schutt (botanist).
Against theory and expectations, the warm tropical Atlantic had much less
plankton than the cold northern seas. Ernst Haeckel was one of the most
fervent condemners of Hensen's results: as on land the tropics must be rich
and the north barren, Haeckel did not understand Hensen's quantitative
approach (how such plankton counting could be carried through without
the ruin of mind and body Haeckel could not conceive). Hensen's student H.
Lohmann also criticized the results as he found abundant nanoplankton that
escaped the nets; however, nanoplankton collected by centrifuging water
samples followed the net plankton distribution observed during the plankton expedition. Superb lithographs illustrate the large, important, and beautiful reports which were completed in 1926.
plankton torpedo plankton net in a torpedo-shaped housing, to be towed behind
a (fast-)moving ship. The basic function of the housing, with a narrow
entrance in front of a funnel-shaped widening, is to reduce the inflow, and,
by the generated underpressure behind the funnel, to increase the flow
through the plankton gauze, which is necessary when fast (up to 6 knots)
hauls are made.