Feeding Currents and Particle Capture Mechanisms in Suspension Feeding Animals

Abstract

The apparent diversity of suspension feeding animals is, in one sense, more apparent than real. Virtually all suspension feeders capture particles from the water at low Reynolds numbers with cylindrical filtering elements, so, at the level of the filtering elements, flow patterns are identical and viscous forces dominate the situation. Six particle capture mechanisms are likely to be operating alone or in combination: (1) scan and trap (isolation of a parcel of fluid containing the particle), (2) sieving, (3) direct interception, (4) inertial impaction, (5) gravitational deposition, and (6) diffusive deposition. To insure that all variables relevant to the suspension feeding process are recorded, future work on suspension feeding should report the diameter and spacing of the filtering elements, flow speeds, diameter of particles available and captured, particle settling velocities, particle mobility (active or passive), and particle surface properties.