Constraints on starting and stopping: behavior compensates for reduced pectoral fin area during braking of the bluegill sunfish<i>Lepomis macrochirus</i>

SUMMARYIn nature, the caudal fins of fish species are frequently lost to some extent by aggressive behaviour, predation and diseases. To test whether the swimming performance of fish with different swimming capacities would be differentially affected due to caudal fin loss and regeneration, we investigated the critical swimming speed (U crit ), swimming metabolic rate (M O2 ), tail beat frequency (f TB ) and tail beat amplitude (A TB ) after caudal fin loss and regeneration (20days) in juveniles of three cyprinid fish species: the qingbo (Spinibarbus sinensis; strong swimmer), the common carp (Cyprinus carpio; intermediate swimmer) and the goldfish (Carassius auratus; poor swimmer). The U crit values of the caudal-fin-lost qingbo, common carp and goldfish were 49, 32 and 35% significantly lower than those of the control groups, respectively. The maximum tail beat amplitude (A TBmax ) (all three fishes), the maximum tail beat frequency (f TBmax ) (only the common carp and the goldfish) and/or the active metabolic rate (M O2active ) (only the common carp) of the caudal-fin-lost fish were significantly higher than those of the control groups. After 20days of recovery, the caudal fins recovered to 41, 47 and 24% of those of the control groups for the qingbo, the common carp and the goldfish, respectively. However, the U crit values of the fin-regenerated qingbo, common carp and goldfish recovered to 86, 91 and 95% of those of the control group, respectively. The caudal-fin-regenerated qingbo and common carp showed a significantly higher A TBmax and f TBmax , respectively, compared with those of the control groups. The qingbo had a higher f TBmax but a lower A TBmax than the common carp and the goldfish, which suggested that a strong swimmer may maintain swimming speed primarily by maintaining a greater f TBmax , for which the caudal fin plays a more important role during swimming, than a poor swimmer. The M O2active of fish (common carp) with a redundant respiratory capacity could increase due to caudal fin loss to meet the increase in energy expenditure required by an increase in f TBmax . In addition, the sustained swimming performance may not be the only selective pressure acting on caudal fin size in these three species, and the present caudal fin size may be a trade-off between sustain swimming performance and other factors (e.g. sexual selection, escape responses). Supplementary material available online at

Section: Discussionmentioning

confidence: 99%

The effects of caudal fin loss and regeneration on the swimming performance of three cyprinid fish with different swimming capacities

Cao

2013

“…Having the area that is influenced by suction generation directed more in front of the fish could make accuracy a more important factor. It has been suggested that braking could increase the accuracy of a suction-feeding fish (Lauder and Drucker, 2004;Higham et al, 2005a;Higham et al, 2005b), and this might be more important for fish that ingest a relatively small volume of water. Future studies that relate braking during suction feeding to mouth size (indirect measure of ingested volume) would provide further insight into this issue.…”

Section: Accuracy During Feedingmentioning

confidence: 99%

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

Higham

Day

Wainwright

2006

Self Cite

140

264

SUMMARY 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.

“…Webb, 1973;Blake, 1979;Drucker and Jensen, 1996a;Drucker and Jensen, 1996b;Walker and Westneat, 1997;Hale et al, 2006), and in arrhythmic movements such as braking (e.g. Drucker and Lauder, 2003;Higham et al, 2005) and maneuvering (e.g. Drucker and Lauder, 2001;Drucker and Lauder, 2003).…”

Section: Introductionmentioning

confidence: 99%

Movement and function of the pectoral fins of the larval zebrafish (Danio rerio) during slow swimming

Green

Hale

2011

SUMMARYPectoral fins are known to play important roles in swimming for many adult fish; however, their functions in fish larvae are unclear. We examined routine pectoral fin movement during rhythmic forward swimming and used genetic ablation to test hypotheses of fin function in larval zebrafish. Fins were active throughout bouts of slow swimming. Initiation was characterized by asymmetric fin abduction that transitioned to alternating rhythmic movement with first fin adduction. During subsequent swimming, fin beat amplitude decreased while tail beat amplitude increased over swimming speeds ranging from 1.47 to 4.56 body lengths per second. There was no change in fin or tail beat frequency with speed (means ± s.d.: 28.2±3.5 and 29.6±1.9Hz, respectively). To examine potential roles of the pectoral fins in swimming, we compared the kinematics of finless larvae generated with a morpholino knockdown of the gene fgf24 to those of normal fish. Pectoral fins were not required for initiation nor did they significantly impact forward rhythmic swimming. We investigated an alternative hypothesis that the fins function in respiration. Dye visualization demonstrated that pectoral fin beats bring distant fluid toward the body and move it caudally behind the fins, disrupting the boundary layer along the body's surface, a major site of oxygen absorption in larvae. Larval zebrafish also demonstrated more fin beating in low oxygen conditions. Our data reject the hypothesis that the pectoral fins of larval zebrafish have a locomotor function during slow, forward locomotion, but are consistent with the hypothesis that the fins have a respiratory function. Supplementary material available online at