| dc.description.abstract | Suction feeding fish draw prey into the mouth using a
flow field that they generate external to the head. In this
paper we present a multidimensional perspective on
suction feeding performance that we illustrate in a
comparative analysis of suction feeding ability in two
members of Centrarchidae, the largemouth bass
(Micropterus salmoides) and bluegill sunfish (Lepomis
macrochirus). We present the first direct measurements of
maximum fluid speed capacity, and we use this to
calculate local fluid acceleration and volumetric flow rate.
We also calculated the ingested volume and a novel metric
of strike accuracy. In addition, we quantified for each
species the effects of gape magnitude, time to peak gape,
and swimming speed on features of the ingested volume of
water. Digital particle image velocimetry (DPIV) and
high-speed video were used to measure the flow in front of
the mouths of three fish from each species in conjunction
with a vertical laser sheet positioned on the mid-sagittal
plane of the fish. From this we quantified the maximum
fluid speed (in the earthbound and fish’s frame of
reference), acceleration and ingested volume. Our method
for determining strike accuracy involved quantifying the
location of the prey relative to the center of the parcel of
ingested water. Bluegill sunfish generated higher fluid
speeds in the earthbound frame of reference, accelerated
the fluid faster, and were more accurate than largemouth
bass. However, largemouth bass ingested a larger volume
of water and generated a higher volumetric flow rate than
bluegill sunfish. In addition, because largemouth bass
swam faster during prey capture, they generated higher
fluid speeds in the fish’s frame of reference. Thus, while
bluegill can exert higher drag forces on stationary prey
items, largemouth bass more quickly close the distance
between themselves and prey. The ingested volume and
volumetric flow rate significantly increased as gape
increased for both species, while time to peak gape had
little effect on the volume. However, peak gape distance
did not affect the maximum fluid speed entering the
mouth for either species. We suggest that species that
generate high fluid speeds in the earthbound frame of
reference will commonly exhibit small mouths and a high
capacity to deliver force to buccal expansion, while species
that ingest a large volume of water and generate high
volumetric flow rates will have larger buccal cavities and
cranial expansion linkage systems that favor displacement
over force delivery. | en_US |
