Chapter 10 Key Concepts

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.