"Matière et Systèmes Complexes"
20 avril 2009 à 11h30
Bâtiment Condorcet, 4ème
étage, salle 454 A.
(Technical University of
A lightning stab in the dark
In the lecture we shall
discuss some recent results on the hydrodynamics of feeding in
planktonic organisms. We first discuss interception feedings for
microorganisms, where the uptake depends on the flow of prey near their
body. In particular, we discuss the role of the flagellate, which,
aside from propelling the organism also secures that the streamliness
pass close to the body. We find that a short flagellum is favourable
for interception feeding, but at the coast of an increase in the drag
of the body of the swimming organism.
Some large marine zooplakters, particularly among copecods, are "ambush
feeders" that passively wait for their prey and capture them by fast
(few ms) surprise attacks. This strategy is obviously very demanding in
terms of muscle power and sensing capabilities, and we have obtained
high-speed video showing the precision maneuvering that takes place -
all the more impressive since the copepods are blind. We shall discuss
the hydrodynamic constraints on this strategy and why it is limited to
larger, muscular species.