Minireview: Ciliary filter feeding and bio‐fluid mechanics—present understanding and unsolved problems

Riisgård, Hans Ulrik; Larsen, Poul Scheel

doi:10.4319/lo.2001.46.4.0882

Cited by 92 publications

(79 citation statements)

References 99 publications

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“…The basic particle capture mechanism in those bivalves that only possess pro-laterofrontal cilia remains poorly understood (Nelson 1960, Owen & McCrae 1976, Beninger et al 1988, Beninger et al 1992, Silverman et al 1995, 1996, Riisgård & Larsen 2001, 2005. According to Owen & McCrae (1976), the laterofrontal tracts of the plicate gill of the scallop Chlamys varia consist of a single row of prolaterofrontal cilia that are 12 to 15 µm long and spaced 0.3 to 0.4 µm apart and their effective beat is towards the frontal face of the filament.…”

Section: Suspension-feeding Without Laterofrontal Cirrimentioning

confidence: 99%

Particle capture mechanisms in suspension-feeding invertebrates

Riisgård¹,

Larsen²

2010

Mar. Ecol. Prog. Ser.

205

179

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A large number of suspension-feeding aquatic animals (e.g. bivalves, polychaetes, ascidians, bryozoans, crustaceans, sponges, echinoderms, cnidarians) have specialized in grazing on not only the 2 to 200 µm phytoplankton but frequently also the 0.5 to 2 µm free-living bacteria, or they have specialized in capturing larger prey, e.g. zooplankton organisms. We review the different particle capture mechanisms in order to illustrate the many solutions to the common problem of obtaining nourishment from a dilute suspension of microscopic food particles. Despite the many differences in morphology and living conditions, particle capture mechanisms may be divided into 2 main types. (1) Filtering or sieving (e.g. through mucus nets, stiff cilia, filter setae), which is found in passive suspension feeders that rely on external currents to bring suspended particles to the filter, and in active suspension feeders that themselves produce a feeding flow by a variety of pump systems. Here the inventiveness of nature does not lie in the capture mechanism but in the type of pump system and filter pore-size. (2) A paddle-like flow manipulating system (e.g. cilia, cirri, tentacles, hair-bearing appendages) that acts to redirect an approaching suspended particle, often along with a surrounding 'fluid parcel', to a strategic location for arrest or further transport. Examples include (1) sieving (e.g. by microvilli in sponge choanocytes, mucus nets in polychaetes, acidians, and salps among others), filter setae in crustaceans, 'ciliary sieving' by stiff laterofrontal cilia in bryozoans and phoronids; and (2) 'cirri trapping' in mussels and other bivalves with eu-laterofrontal cirri, ciliary 'catch-up' in bivalve and gastropod veliger larvae, some polychaetes, entroprocts, and cycliophores. These capture mechanisms may involve contact with a particle, and possibly mechanoreception or chemoreception, or may include redirection of particles by the interaction of multiple currents (e.g. in scallops and other bivalves without eu-laterofrontal cirri). Based on the review, we discuss the current physical and biological understanding of the capture process and suggest a number of specific problems related to particle capture, which may be solved in the future using advanced theoretical, computational and experimental techniques.

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Section: Suspension-feeding Without Laterofrontal Cirrimentioning

confidence: 99%

Particle capture mechanisms in suspension-feeding invertebrates

Riisgård¹,

Larsen²

2010

Mar. Ecol. Prog. Ser.

205

179

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“…A cylindrical geometry approximates a variety of natural collectors such as reed-like wetland vegetation (e.g., Spartina alterniflora, Phragmites australis); submerged benthic plants and algae (Harvey et al 1995); and cilia, bristles, tube-feet and other filamentous structures of suspension feeders (Shimeta and Jumars 1991;Wildish and Kristmanson 1997;Riisgard and Larsen 2001). The relevant length scale for flow around a cylinder is the diameter, d c , and flow structure is defined by the collector Reynolds number, Re c ϭ ud c /v, where u is flow velocity and v is kinematic viscosity.…”

mentioning

confidence: 99%

Observations of particle capture on a cylindrical collector: Implications for particle accumulation and removal in aquatic systems

Palmer

Nepf

Pettersson

et al. 2004

Limnology & Oceanography

129

232

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Capture of suspended particles by cylindrical collectors is an important mechanism in many aquatic processes, such as larval settlement, suspension feeding, and vegetative filtration. In these processes, the collector Reynolds number (Re c ), based on the collector diameter, ranges from well below 1 to 1,000. No analytical solutions exist to describe capture over most of this range. Capture is typically described by the efficiency, , defined as the ratio of the upstream span of particles that are captured on the collector to the collector diameter. Here, laboratory experiments are used to measure capture efficiency of a single cylinder as a function of Re c and particle ratio, R, which is the ratio of particle diameter to collector diameter. Re c is varied from 50 to 500 and three values of R are used: 0.03, 0.015, and 0.008. The selected particles have a specific gravity of 1.03. For smooth cylinders, capture increases with both Re c and R but is more strongly dependent on R. This result indicates that, in aquatic systems, where flow velocity and suspended particle type and size are fixed, higher capture efficiency will occur on the smallest collectors (those with largest R). Furthermore, we examine a similar experiment in which particles are collected by branched structures. We show that capture to individual cylindrical branches within a compound structure can be predicted by single-cylinder efficiencies. Finally, capture was increased when roughness elements were added to the collectors.

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“…Various capture strategies have been documented in ciliated filter feeders, ranging from ciliary sieving to upstream interception of particles, particle trapping, and downstream particle interception. 7 Experimental observations suggest that particle capture process by downstream interception is passive and mechanical; that is, it does not seem to rely on active sensing of the suspended particles. 16 Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Many microorganisms including marine larvae use motile cilia to generate feeding currents. [6][7][8] Cilia-generated flows are characterized by low Re, of the order 10 −4 to 10 −2 even in water, where Stokes equations are applicable. To break the time reversibility inherent in the Stokes regime, motile cilia typically use two mechanisms: (1) an asymmetric beating pattern at the level of the individual cilium, and (2) a metachronal wave pattern in cilia beating collectively.…”

Section: Introductionmentioning

confidence: 99%

“…The ciliated organ is characterized by a band of cilia that serves the dual function of generating feeding currents and directly intercepting particles downstream of the cilia. 7 It is hypothesized that downstream particle collection is based on the "catch-up" principle. 10 According to this principle, cilia move the fluid with suspended particles into the ciliary region, where the same cilia, during their effective stroke, catch up with suspended particles and transfer them to a food groove or mouth cavity.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Selective particle capture by asynchronously beating cilia

Ding

Kanso

2015

Physics of Fluids

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Selective particle filtration is fundamental in many engineering and biological systems. For example, many aquatic microorganisms use filter feeding to capture food particles from the surrounding fluid, using motile cilia. One of the capture strategies is to use the same cilia to generate feeding currents and to intercept particles when the particles are on the downstream side of the cilia. Here, we develop a 3D computational model of ciliary bands interacting with flow suspended particles and calculate particle trajectories for a range of particle sizes. Consistent with experimental observations, we find optimal particle sizes that maximize capture rate. The optimal size depends nonlinearly on cilia spacing and cilia coordination, synchronous vs. asynchronous. These parameters affect the cilia-generated flow field, which in turn affects particle trajectories. The low capture rate of smaller particles is due to the particles' inability to cross the flow streamlines of neighboring cilia. Meanwhile, large particles have difficulty entering the sub-ciliary region once advected downstream, also resulting in low capture rates. The optimal range of particle sizes is enhanced when cilia beat asynchronously. These findings have potentially important implications on the design and use of biomimetic cilia in processes such as particle sorting in microfluidic devices. C 2015 AIP Publishing LLC. [http://dx

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Minireview: Ciliary filter feeding and bio‐fluid mechanics—present understanding and unsolved problems

Cited by 92 publications

References 99 publications

Particle capture mechanisms in suspension-feeding invertebrates

Particle capture mechanisms in suspension-feeding invertebrates

Observations of particle capture on a cylindrical collector: Implications for particle accumulation and removal in aquatic systems

Selective particle capture by asynchronously beating cilia

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