Body Fineness Ratio as a Predictor of Maximum Prolonged-Swimming Speed in Coral Reef Fishes

Abstract

The ability to sustain high swimming speeds is believed to be an important factor affecting resource acquisition in fishes. While we have gained insights into how fin morphology and motion influences swimming performance in coral reef fishes, the role of other traits, such as body shape, remains poorly understood. We explore the ability of two mechanistic models of the causal relationship between body fineness ratio and endurance swimming-performance to predict maximum prolonged-swimming speed (Umax) among 84 fish species from the Great Barrier Reef, Australia. A drag model, based on semi-empirical data on the drag of rigid, submerged bodies of revolution, was applied to species that employ pectoral-fin propulsion with a rigid body at U max. An alternative model, based on the results of computer simulations of optimal shape in self-propelled undulating bodies, was applied to the species that swim by body-caudal-fin propulsion at Umax. For pectoral-fin swimmers, Umax increased with fineness, and the rate of increase decreased with fineness, as predicted by the drag model. While the mechanistic and statistical models of the relationship between fineness and Umax were very similar, the mechanistic (and statistical) model explained only a small fraction of the variance in Umax. For body-caudal-fin swimmers, we found a non-linear relationship between fineness and Umax, which was largely negative over most of the range of fineness. This pattern fails to support either predictions from the computational models or standard functional interpretations of body shape variation in fishes. Our results suggest that the widespread hypothesis that a more optimal fineness increases endurance-swimming performance via reduced drag should be limited to fishes that swim with rigid bodies.

Relationship between swimming capacities and morphological traits of fish larvae at settlement stage: a study of several coastal Mediterranean species

“…Groups or species with small sample sizes ( n < 15) were not included in the correlation tests but were included in the predictive models and the general presentation of results (Table and Figure ). Many studies have tested morphological traits as predictors of dispersal and swimming capacities (Cui et al, ; Fisher et al, ; Fisher & Hogan, ; Leis et al, ; Raventós, ; Teichert et al, ; Walker et al, ; Wilson & Meekan, ). Our observations, aligned with previous results, suggest that fish larval morphologies are better predictors of swimming capacity than their taxonomic identity (Fisher et al, ; Fisher & Bellwood, ; Fisher & Hogan, ).…”

Differences in swimming performance and energetic costs between an endangered native toothcarp (Aphanius iberus) and an invasive mosquitofish (Gambusia holbrooki)

“…Two morphometric ratios were then obtained from these measurements: fineness ratio (ratio between standard body length and maximum body depth) and caudal peduncle depth factor (ratio between least depth of caudal peduncle and maximum body depth). Both morphological ratios have been previously used as predictors of swimming ability and efficiency (Fisher & Hogan, ; Ohlberger et al, ; Scarnecchia, ; Walker et al, ; Webb, ).…”

Sexual dimorphism in black jaw tiliapia (Sarotherodon melanotheron) and banded jewelfish (Hemichromis fasciatus) from the Great Kwa River, Calabar, Nigeria

“…Elsewhere, Leris et al (2013) quantified body shape variations between the sexes of D. rerio and reported that females had deeper body depth and width compared with males. Walker et al (2013) demonstrated that shallower body depth is thought to reduce drag during sustained swimming and thus is favoured in open water (pelagic) habitat and, in contrast, deeper body depth is also thought to increase manouverability and boost swimming speed, and thus is favoured in habitat with many hiding places. Therefore, sexual dimorphism of the observed species recorded in body depth in H. fasciatus from the Great Kwa River may probably have resulted as an adaptation for strong river current and defending of territory.…”

“…As such, the dimorphic patterns of body depth and standard length between sexes are expected to contribute to differing locomotor potential between female and male individuals of this species. Some authors have reported that body shape traits contribute to performance variations (Langerhans and Reznick, 2010;Walker et al, 2013), prolonged swimming speed and associated morphological performance (Arnold, 1983(Arnold, , 2003Walker, 2007). Overall, the positive relationship between the right pectoral fin and increased gonad weight in S. melanotheron suggests that larger pectoral fins in females were more likely to be primarily affiliated with reproductive activity, while larger body depth of female H. fasciatus and its highlighted role in sexual dimorphism of this species is more suggestive of being primarily for locomotor function.…”