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Anatomy
how algae moVe
Cytoplasm, cell walls, and skeletons of algae have a density greater than the medium these organisms dwell in. The density of freshwater is 1.0 g cm −3 and that of seawater ranges from 1.021 to
1.028 g cm −3 , but most cytoplasmic components have a density between 1.03 and 1.10 g cm −3 , the
silica forming the diatom frustule and the scales of Chrysophyceae have a density of 2.6 g cm −3 , and
both calcite and aragonite of Haptophyta coccoliths reach an even higher value of 2.7 g cm −3 . With
this density values, algae must inevitably sink. Therefore, one of the problems planktonic organisms
face (organisms that wander in the water and/or are carried about by the movements of the water
rather than by their own ability to swim) is how to keep afloat in a suitable attitude between whatever levels are suitable for their life. The phytoplankton must obviously remain floating quite close
to the surface because only there is a sufficient illumination for photosynthesis. There are broadly
two solutions by which algae can keep afloat and regulate their orientation and depth: a dynamic
solution, obtaining lift by swimming, and a static solution, by buoyancy control, or through adaptations reducing sinking rates. In many cases, the two solutions function together.
Swimming
What does swimming mean? It means that an organism immersed in a liquid environment is able to
sustain movement by deforming its body in a periodic way.
The algae are all good movers or better good swimmers. They swim more or less continuously
and control their level chiefly by this means. For example, dinoflagellates, which can achieve speed
TF
FLC
FC
TSR
SCB
SC
NFC
N
SC
FC
FLC
LF
MMLR
NSF
FIGURE 2.58 Root system of Dinophyceae. TF: transverse flagellum; LF: longitudinal flagellum; SCB: striated
connective band; MMLR: multimembered longitudinal root; TSR: transverse striated root; SC: striated connectives; NFC: nuclear fibrous connective; N: nucleus; FC: fibrous collars; FLC: flagellar canals; NSF: nonstriated fiber.
Anatomy
how algae moVe
Cytoplasm, cell walls, and skeletons of algae have a density greater than the medium these organisms dwell in. The density of freshwater is 1.0 g cm −3 and that of seawater ranges from 1.021 to
1.028 g cm −3 , but most cytoplasmic components have a density between 1.03 and 1.10 g cm −3 , the
silica forming the diatom frustule and the scales of Chrysophyceae have a density of 2.6 g cm −3 , and
both calcite and aragonite of Haptophyta coccoliths reach an even higher value of 2.7 g cm −3 . With
this density values, algae must inevitably sink. Therefore, one of the problems planktonic organisms
face (organisms that wander in the water and/or are carried about by the movements of the water
rather than by their own ability to swim) is how to keep afloat in a suitable attitude between whatever levels are suitable for their life. The phytoplankton must obviously remain floating quite close
to the surface because only there is a sufficient illumination for photosynthesis. There are broadly
two solutions by which algae can keep afloat and regulate their orientation and depth: a dynamic
solution, obtaining lift by swimming, and a static solution, by buoyancy control, or through adaptations reducing sinking rates. In many cases, the two solutions function together.
Swimming
What does swimming mean? It means that an organism immersed in a liquid environment is able to
sustain movement by deforming its body in a periodic way.
The algae are all good movers or better good swimmers. They swim more or less continuously
and control their level chiefly by this means. For example, dinoflagellates, which can achieve speed
TF
FLC
FC
TSR
SCB
SC
NFC
N
SC
FC
FLC
LF
MMLR
NSF
FIGURE 2.58 Root system of Dinophyceae. TF: transverse flagellum; LF: longitudinal flagellum; SCB: striated
connective band; MMLR: multimembered longitudinal root; TSR: transverse striated root; SC: striated connectives; NFC: nuclear fibrous connective; N: nucleus; FC: fibrous collars; FLC: flagellar canals; NSF: nonstriated fiber.