title: Flow disturbances generated by feeding and swimming zooplankton.
abstract: Interactions between planktonic organisms, such as detection of prey, predators, and mates, are often mediated by fluid signals. Consequently, many plankton predators perceive their prey from the fluid disturbances that it generates when it feeds and swims. Zooplankton should therefore seek to minimize the fluid disturbance that they produce. By means of particle image velocimetry, we describe the fluid disturbances produced by feeding and swimming in zooplankton with diverse propulsion mechanisms and ranging from 10-µm flagellates to greater than millimeter-sized copepods. We show that zooplankton, in which feeding and swimming are separate processes, produce flow disturbances during swimming with a much faster spatial attenuation (velocity u varies with distance r as u ∝ r(-3) to r(-4)) than that produced by zooplankton for which feeding and propulsion are the same process (u ∝ r(-1) to r(-2)). As a result, the spatial extension of the fluid disturbance produced by swimmers is an order of magnitude smaller than that produced by feeders at similar Reynolds numbers. The "quiet" propulsion of swimmers is achieved either through swimming erratically by short-lasting power strokes, generating viscous vortex rings, or by "breast-stroke swimming." Both produce rapidly attenuating flows. The more "noisy" swimming of those that are constrained by a need to simultaneously feed is due to constantly beating flagella or appendages that are positioned either anteriorly or posteriorly on the (cell) body. These patterns transcend differences in size and taxonomy and have thus evolved multiple times, suggesting a strong selective pressure to minimize predation risk.
authors: Centre for Ocean Life, National Institute of Aquatic Resources, Technical University of Denmark, 2920 Charlottenlund, Denmark; tk@aqua.dtu.dk.
authors: Thomas
authors: T
authors: Kiørboe
authors: Department of Applied Ocean Physics and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA 02543;
authors: Houshuo
authors: H
authors: Jiang
authors: Centre for Ocean Life, National Institute of Aquatic Resources, Technical University of Denmark, 2920 Charlottenlund, Denmark;Área de Ecología Animal, Estación de Fotobiología Playa Unión, 9103 Rawson, Chubut, Argentina; and.
authors: Rodrigo Javier
authors: http://orcid.org/0000-0002-4332-2312
authors: RJ
authors: Gonçalves
authors: Centre for Ocean Life, National Institute of Aquatic Resources, Technical University of Denmark, 2920 Charlottenlund, Denmark;
authors: Lasse Tor
authors: LT
authors: Nielsen
authors: Centre for Ocean Life, Department of Physics, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark.
authors: Navish
authors: N
authors: Wadhwa
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D016798:Ciliophora / Q000502:physiology; D033342:Copepoda / Q000502:physiology; D004141:Dinoflagellida / Q000502:physiology; D004435:Eating / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology; D005260:Female; D057446:Hydrodynamics; D008297:Male; D008954:Models, Biological; D009068:Movement / Q000502:physiology; D012212:Rheology; D015398:Signal Transduction; D013550:Swimming / Q000502:physiology; D014741:Video Recording; D015048:Zooplankton / Q000502:physiology*
keywords: biological fluid dynamics; optimization