Functional regionalization of the pectoral fin of the benthic longhorn sculpin during station holding and swimming

Taft, Natalia K.; Lauder, George V.; Madden, P.

doi:10.1111/j.1469-7998.2008.00472.x

Cited by 32 publications

(59 citation statements)

References 22 publications

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“…Currently, we know of only two studies that have measured the curvature of individual fin rays during locomotion [dorsal and anal fins of bluegill sunfish (Standen and Lauder, 2005), pectoral fins of longhorn sculpin (Taft et al, 2008)]. However, in both of these studies, curvature was measured only along the length of the fin rays, irrespective of the fin surface.…”

Section: Introductionmentioning

confidence: 97%

Median fin function during the escape response of bluegill sunfish (Lepomis macrochirus). II: Fin-ray curvature

Chadwell

Standen

Lauder

et al. 2012

Journal of Experimental Biology

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SUMMARYAlthough kinematic analysis of individual fin rays provides valuable insight into the contribution of median fins to C-start performance, it paints an incomplete picture of the complex movements and deformation of the flexible fin surface. To expand our analysis of median fin function during the escape response of bluegill sunfish (Lepomis macrochirus), patterns of spanwise and chordwise curvature of the soft dorsal and anal fin surfaces were examined from the same video sequences previously used in analysis of fin-ray movement and orientation. We found that both the span and chord undergo undulation, starting in the anterior region of either fin. Initiated early in Stage 1 of the C-start, the undulation travels in a postero-distal direction, reaching the trailing edge of the fins during early Stage 2. Maximum spanwise curvature typically occurred among the more flexible posterior fin rays, though there was no consistent correlation between maximum curvature and fin-ray position. Undulatory patterns suggest different mechanisms of action for the fin regions. In the anterior fin region, where the fin rays are oriented dorsoventrally, undulation is directed primarily chordwise, initiating a transfer of momentum into the water to overcome the inertia of the flow and direct the water posteriorly. Within the posterior region, where the fin rays are oriented caudally, undulation is predominantly directed spanwise; thus, the posterior fin region acts to ultimately accelerate this water towards the tail to increase thrust forces. Treatment of median fins as appendages with uniform properties does not do justice to their complexity and effectiveness as control surfaces. Supplementary material available online at

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Section: Introductionmentioning

confidence: 97%

Median fin function during the escape response of bluegill sunfish (Lepomis macrochirus). II: Fin-ray curvature

Chadwell

Standen

Lauder

et al. 2012

Journal of Experimental Biology

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“…Curvature () is defined as the change in the unit tangent vector divided by the change in the arc length curve (Taft et al, 2008). One caveat regarding the use of splines to estimate curvature is that they can yield spurious local peaks in curvature at the knots where one piecewise polynomial function is replaced by the next.…”

Section: Estimation Of Fin Ray Curvaturementioning

confidence: 99%

“…They use their large, fan-like pectoral fins to support their weight and rapidly push off from the substrate as well as for swimming in the open water (Taft et al, 2008). It has been shown that the pectoral fin of this species is functionally regionalized, with the more ventral rays being used for direct substrate contact and the dorsal rays being used during slow swimming (Taft et al, 2008). The individual lepidotrichia are also divided into distinct morphological regions (Fig.1).…”

Section: Introductionmentioning

confidence: 99%

“…They lack swimbladders and are negatively buoyant in the water (Bidelow and Shroeder, 1953;Taft et al, 2008). They use their large, fan-like pectoral fins to support their weight and rapidly push off from the substrate as well as for swimming in the open water (Taft et al, 2008). It has been shown that the pectoral fin of this species is functionally regionalized, with the more ventral rays being used for direct substrate contact and the dorsal rays being used during slow swimming (Taft et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Functional implications of morphological specializations among the pectoral fin rays of the benthic longhorn sculpin

Taft

2012

Journal of Experimental Biology

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SUMMARYFin ray structure in ray-finned fishes (Actinopterygii) largely defines fin function. Fin rays convert the muscle activity at the base of the fin to shape changes throughout the external fin web. Despite their critical functional significance, very little is known about the relationship between form and function in this key vertebrate structure. In this study we demonstrate that morphological specializations of the pectoral fin rays of the benthic longhorn sculpin (Myoxocephalus octodecimspinosus) have specific functional consequences both within and among individual rays. The fin rays of longhorn sculpin have an elongate unjointed region with a cylindrical shape in cross-section proximally, and are jointed with a crescent-shaped cross-section distally. Variation in the relative length of the proximal versus distal regions affects the location of maximum curvature as well as the mean curvature along the length of individual rays. We experimentally manipulated fin rays to mimic the differential muscle activity that generates curvature of fin rays in living animals. We found that the shape of the fin rays in cross-section affects their curvature. Among fin rays, the most ventral fin rays with relatively longer proximal unjointed regions have a more distal location of maximum curvature. These ventral rays also have higher mean curvature, likely because of a combination of features including the crosssectional shape, area and diameter of the distal segments as well as their relative size and number, which were not examined in detail here. Because these rays are used routinely for substrate contact, this higher curvature could contribute to increased flexibility for substrate contact behaviors such as clinging or gripping the substrate. These morphological and functional differences among fin rays are correlated with the functional regionalization of the fin. Specifically, the ventral fin rays that are used during substrate contact are more stiff proximally and more highly curved distally than the pectoral rays in the dorsal region, which are longer and used during slow swimming. This study highlights the importance of examining morphological and functional variation both within and among complex structures such as fin rays.

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Morphological divergence of the threatened Rocky Mountain sculpin (Cottus sp.) is driven by biogeography and flow regime: Implications for mitigating altered flow regime to freshwater fishes

Rudolfsen

Watkinson

Poesch

2017

Aquatic Conservation

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Abstract1. Stream hydrology is considered the primary factor in structuring freshwater fish communities, influencing stream habitats, food resources, and life-history characteristics. Changes in stream hydrology, from climate change and anthropogenic sources (e.g. dams, irrigation channels), are thought to have adverse impacts on many freshwater species. 3. Using geometric morphometrics and meristic counts, body shape, fin rays, and sensory pores were compared. As hypothesized, high-flow river systems were correlated with sculpin with more dorsoventrally compressed, slender body shapes that minimized resistance to flow (P<0.001). Rocky Mountain sculpin had more pectoral fin rays in populations with higher flows than lower flows, potentially allowing them to increase friction when gripping onto the substrate (P<0.001), and more anteriorly and dorsally located head pores to improve detection of floating prey (P<0.001).4. Biogeographic isolation and difference in flow regime were the likely basis for the observed morphological variation. The degree to which these phenotypes become fixed is unknown; however, since phenotypic diversity parallels genetic diversity in Rocky Mountain sculpin, there is the possibility that persistent selection of these phenotypes can make it difficult to adapt to rapidly changing habitat conditions, such as changing flow.5. This study emphasizes the importance of considering phenotypic and morphological variation when evaluating how best to mitigate anthropogenic stressors and their impact on freshwater fishes.

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Functional regionalization of the pectoral fin of the benthic longhorn sculpin during station holding and swimming

Cited by 32 publications

References 22 publications

Median fin function during the escape response of bluegill sunfish (Lepomis macrochirus). II: Fin-ray curvature

Median fin function during the escape response of bluegill sunfish (Lepomis macrochirus). II: Fin-ray curvature

Functional implications of morphological specializations among the pectoral fin rays of the benthic longhorn sculpin

Morphological divergence of the threatened Rocky Mountain sculpin (Cottus sp.) is driven by biogeography and flow regime: Implications for mitigating altered flow regime to freshwater fishes

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