• Plankton are rarely distributed homogeneously throughout the ocean. Rather, we see strong spatial differences in plankton abundance, to the degree that many plankton species occur in discrete patches.
  • Phytoplankton and smaller zooplankton distributions are often determined by localized wind patterns.
  • Phytoplankton density results from a balance between population growth and dispersive processes caused by turbulence and wind.
  • Zooplankton often occur in patches as a result of behavioral aggregations and periodic movements. Such aggregations may attract predators.
  • Many planktonic organisms undergo diel vertical migrations: They move toward the surface at night and descend during the day. The behavior is controlled by a biological clock that is reinforced by environmental light cues.
  • Convincing explanations of this behavior include the effects of predation and the potential of energy savings of poikilotherms by diving to cooler waters.
  • Schooling is coordinated aggregation and movement and is common among fish and some cephalopods.
  • New archival satellite tag technologies allow long- distance tagging of large migratory fish. The results are startling: Large oceanic fish typically move across and between oceans.
  • Large geographic scale movements of nekton and seabirds in the ocean are selected to maximize efficient use of habitats for feeding and breeding, which may shift seasonally in availability.
  • Movements of whales and large fishes demonstrate that large nekton can adjust large-scale movements to maximize local and geographically shifting food supplies, especially at sites of upwelling.
  • A multispecies tagging program throughout the North Pacific Ocean has demonstrated the presence of very- large-scale current systems and long-distance swimming of many large-bodied nekton, including fish, turtles, and mammals.
  • Surface waters are the ultimate source of material that sinks to the deep, but many plankton are adapted to reduce sinking.
  • Small zooplankton and phytoplankton live in a world dominated by low Reynolds numbers.
  • The vertical position of plankton is determined by the bulk density of the organism, structures that create drag, water motion, and swimming ability.
  • Organisms living at greater and greater depths experience decreasing food input and rapidly extinguishing light.
  • Predation is intense in the plankton at all depths. Both phytoplankton and zooplankton rely on evolved armature, chemical defenses, and transparency to avoid predation.
  • Many phytoplankton species are defended by toxic substances.
  • As depths increase toward 1,000 m, light diminishes, and organisms must use special adaptations to deal with diminishing and even absent sunlight originating from above.
  • At bathypelagic and deeper depths, animals use bioluminescence based on the luciferin-luciferase system or the photoprotein-calcium system in a variety of adaptations to avoid predation.
  • Bioluminescence has often involved the elaborate evolution of interaction and cooperation between a host and symbiotic bioluminescent bacteria.
  • Low densities of prey in meso- and bathypelagic depths have resulted in a set of offense and defense adaptations to detect or attract prey and to thwart predators.
  • Midwater fishes employ color-shading and counterillumination generated by ventral bioluminescent organs, to hide their position in low- sunlight conditions.
  • Bioluminescence can be used for offense by projecting a light signal that is invisible to prey or by using luminescent lures to attract prey.
  • Mesopelagic fishes are adapted for dealing with consumption of rare prey
  • Bathypelagic and abyssopelagic fishes are not very active.
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