Morphology predicts suction feeding performance in centrarchid fishes

Abstract

Suction feeding fish differ in their capacity to generate subambient pressure while feeding, and these differences appear to relate to morphological variation. We developed a morphological model of force transmission in the fish head and parameterized it with measurements from individual fish. The model was applied to 45 individuals from five species of centrarchid fishes: Lepomis macrochirus, Lepomis punctatus, Lepomis microlophus, Micropterus salmoides and Pomoxis nigromaculatus. Measurements of epaxial cross-sectional area, epaxial moment arm, buccal area and buccal area moment arm were combined to estimate pressure generation capacity for individual fish. This estimation was correlated with pressure measured in fish feeding on elusive prey to test the model's ability to predict pressure generation from morphology. The model explained differences in pressure generation found among individuals (P<0.001, r 2 =0.71) and produced a realistic estimate of normalized muscle stress during suction feeding (68.5±6.7·kPa). Fish with smaller mouths, larger epaxial cross-sectional area and longer epaxial moments, such as L. macrochirus (bluegill sunfish), generated lower pressures than fish with larger mouths, smaller cross-sectional area and shorter moments, such as M. salmoides (largemouth bass). These results reveal a direct trade-off between morphological requirements of feeding on larger prey (larger mouth size relative to body depth) and the ability to generate subambient pressure while suction feeding on elusive prey.

Multidimensional analysis of suction feeding performance in fishes: fluid speed, acceleration, strike accuracy and the ingested volume of water

“…We emphasize that the comparisons we draw between the two species are therefore restricted to fish in a narrow size range. It is likely that many of the parameters we measured will change with body size in these species (Carroll et al, 2004).…”

“…One example of where our understanding of performance remains imperfect is with feeding in fishes. Prey capture by fishes offers excellent potential for a unified view of performance across a large slice of vertebrate life because most fish species use the same basic suction feeding mechanism to capture their prey, and yet there is tremendous diversity in size and shape of the feeding apparatus and a complete understanding of the implications of this diversity for suction feeding ability is still lacking (Carroll et al, 2004;Muller and Osse, 1984;Norton and Brainerd, 1993;Van Wassenbergh et al, 2005;Wainwright et al, 2001).…”

“…difference between the speed of the prey and the speed of the fluid surrounding the prey) and because a rapid flow presumably limits the time for prey escape. Variation in fluid speed has been inferred indirectly by tracking the prey movement towards the predator (Norton and Brainerd, 1993;Cook, 1996;Van Leeuwen, 1984;Wainwright et al, 2001;Waltzek and Wainwright, 2003) or by measuring the magnitude of subambient pressure in the buccal cavity (Lauder, 1980;Lauder, 1983;Lauder et al, 1986;Nemeth, 1997;Sanford and Wainwright, 2002;Carroll et al, 2004). A few studies have directly quantified the flow speeds generated by suction feeders (Muller and Osse, 1984;Van Leeuwen, 1984;Ferry-Graham et al, 2003;Higham et al, 2005a), but to date there has been no attempt to measure the peak fluid speeds that an individual or species is capable of generating.…”

“…Although Drost et al estimated the acceleration of fluid during suction feeding in larval fish (Drost et al, 1988), the potential importance of fluid acceleration has been ignored in most recent considerations of suction feeding performance (e.g. Carroll et al, 2004;Van Wassenbergh et al, 2005;Wainwright et al, 2001).…”

Treated Wastewater Effluent Reduces Sperm Motility Along an Osmolality Gradient

“…Only the highest sperm performance for each treatment and fish, rather then the average of each triplicate analysis, was selected for the statistical analysis. The selection of only the highest performance among multiple observations is consistent with the functionality of sperm activation (which only occurs once) and the biomechanical performance literature, which assumes that unique behaviors are likely underestimated in laboratory settings, but cannot be overestimated due to the physiological and mechanical constraints of the observed organism (i.e., sperm) (Full et al 1995;Farley 1997;Swanson et al 1998;Wilson et al 2000;Carroll et al 2004). …”