4.5 Paper V: Capture of nite-sized prey
Sloppy feeders capture large prey with much higher clearance rates than small prey
(gure 4.9 B), shifting their physically selected prey size spectrum towards larger
We further nd, with an analytical calculation for advective capture, that the clearance
rate is increased by about 30% due to the hydrodynamic interaction between a
large predator with small nite-sized spherical prey. The resulting approximate formula
for small prey is Q 2 U r2p
with the predator speed U and the prey radius rp.
For this the hydrodynamic interaction is estimated with Faxen forces, due to which
the prey trajectories dier from the ow streamlines before contact.
Direct interception feeders, which do not create enhancing feeding currents with
agella, seem not able to capture as much prey as lter-feeding microbes can collect
purely by sieving and as is required for the survival as an animal without additional
resources (light, dissolved nutrients). Capture rates for such direct interception feeders
are consistently low, even though the organisms can feed on a large prey size range,
that spans at least two orders of magnitude in prey length.