Body Surface Area in Galeoid Sharks

Musick, John A.; Tabit, Christopher R.; Evans, D. A.

doi:10.2307/1446498

Cited by 7 publications

(6 citation statements)

References 6 publications

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“…Moreover, liver size and lipid stores are not the only factors that influence buoyancy, which can also be modulated by alterations to the chemical composition of the liver (Pinte et al, 2019;Wetherbee & Nichols, 2000). For these reasons, and the large energetic cost of increased girth (Iosilevskii & Papastamatiou, 2016;Musick et al, 1990), we suggest that this result provides further evidence against migratory behaviour in M. henlei. This is further supported by the fact that based on existing studies in related taxa utilising the same measures of girth, the extent of positive girth allometry correlates negatively with the extent of migratory behaviour (Gayford et al, 2023).…”

Section: Girth Morphology: Implications For Ecology and Evolutionmentioning

confidence: 76%

Ontogenetic morphometry of the brown smoothhound sharkMustelus henleiwith implications for ecology and evolution

Gayford

Godfrey²,

Whitehead

2023

Journal of Morphology

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The central tenet of ecomorphology links ecological and morphological variation through the process of selection. Traditionally used to rationalise morphological differences between taxa, an ecomorphological approach is increasingly being utilised to study morphological differences expressed through ontogeny. Elasmobranchii (sharks, rays and skates) is one clade in which such ontogenetic shifts in body form have been reported. Such studies are limited to a relatively small proportion of total elasmobranch ecological and morphological diversity, and questions remain regarding the extent to which ecological selection are driving observed morphometric trends. In this study, we report ontogenetic growth trajectories obtained via traditional linear morphometrics from a large data set of the brown smoothhound shark (Mustelus henlei). We consider various morphological structures including the caudal, dorsal and pectoral fins, as well as several girth measurements. We use an ecomorphological approach to infer the broad ecological characteristics of this population and refine understanding of the selective forces underlying the evolution of specific morphological structures. We suggest that observed scaling trends in M. henlei are inconsistent with migratory behaviour, but do not contradict a putative trophic niche shift. We also highlight the role of predation pressure and sex‐based ecological differences in driving observed trends in morphometry, a factor which has previously been neglected when considering the evolution of body form in sharks.

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Section: Girth Morphology: Implications For Ecology and Evolutionmentioning

confidence: 76%

Ontogenetic morphometry of the brown smoothhound sharkMustelus henleiwith implications for ecology and evolution

Gayford

Godfrey²,

Whitehead

2023

Journal of Morphology

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“…For example, it is about 0.2 for present sailfish, 0.25 for dogfish [58] , 0.28 for pike [59] , 0.3 for present swordfish, and 0.41 (or 0.54) for trout [59] , [60] , respectively. Here, the bill is excluded in the calculation of the ratios of the present sailfish and swordfish, and Musick et al [58] and Tytell [60] used the standard length (from the snout to the end of the vertebra) and the body length, respectively, instead of the total length of fish. Therefore, owing to the uncertainty of the wetted area and different experimental conditions, it is difficult to make a firm conclusion on which fish has lower drag coefficient than others.…”

Section: Resultsmentioning

confidence: 99%

Hydrodynamic Characteristics of the Sailfish (Istiophorus platypterus) and Swordfish (Xiphias gladius) in Gliding Postures at Their Cruise Speeds

2013

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The sailfish and swordfish are known as the fastest sea animals, reaching their maximum speeds of around 100 km/h. In the present study, we investigate the hydrodynamic characteristics of these fishes in their cruise speeds of about 1 body length per second. We install a taxidermy specimen of each fish in a wind tunnel, and measure the drag on its body and boundary-layer velocity above its body surface at the Reynolds number corresponding to its cruising condition. The drag coefficients of the sailfish and swordfish based on the free-stream velocity and their wetted areas are measured to be 0.0075 and 0.0091, respectively, at their cruising conditions. These drag coefficients are very low and comparable to those of tuna and pike and smaller than those of dogfish and small-size trout. On the other hand, the long bill is one of the most distinguished features of these fishes from other fishes, and we study its role on the ability of drag modification. The drag on the fish without the bill or with an artificially-made shorter one is slightly smaller than that with the original bill, indicating that the bill itself does not contribute to any drag reduction at its cruise speed. From the velocity measurement near the body surface, we find that at the cruise speed flow separation does not occur over the whole body even without the bill, and the boundary layer flow is affected only at the anterior part of the body by the bill.

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“…The scaling of both lean tissue and liver tissue volume was best described by Naylor's branch lengths, featuring strong Table 1. Hydrodynamic modelling, as expressed in terms of density of seawater (r w ); standard length (SL); body maximal width (TM); body volume (BV); body wetted area (SA) [34]; fineness ratio (FR ¼ SL/TM); added mass coefficient (k; ellipsoid of same FR [33]); negative buoyancy (W ) (body weight, minus buoyancy); time-varying speed U(t) and acceleration a(t); cruising speed just prior to acceleration (CS); (non-dimensional) time to accelerate over one body length (n s ); and body volume BV expressed as a fraction of ellipsoid volume (w ¼ BV FR 2 /(p/6) SL 3 ). In the total drag equation, the first, second and third terms correspond to parasite, induced and added mass drag, respectively [6,11,12].…”

Section: (A) Evolution Of Buoyancy Control (I) Scaling and Calculation Of Residualsmentioning

confidence: 99%

Physical trade-offs shape the evolution of buoyancy control in sharks

2017

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Buoyancy control is a fundamental aspect of aquatic life that has major implications for locomotor performance and ecological niche. Unlike terrestrial animals, the densities of aquatic animals are similar to the supporting fluid, thus even small changes in body density may have profound effects on locomotion. Here, we analysed the body composition (lipid versus lean tissue) of 32 shark species to study the evolution of buoyancy. Our comparative phylogenetic analyses indicate that although lean tissue displays minor positive allometry, liver volume exhibits pronounced positive allometry, suggesting that larger sharks evolved bulkier body compositions by adding lipid tissue to lean tissue rather than substituting lean for lipid tissue, particularly in the liver. We revealed a continuum of buoyancy control strategies that ranged from more buoyant sharks with larger livers in deeper ecosystems to relatively denser sharks with small livers in epipelagic habitats. Across this eco-morphological spectrum, our hydrodynamic modelling suggests that neutral buoyancy yields lower drag and more efficient steady swimming, whereas negative buoyancy may be more efficient during accelerated movements. The evolution of buoyancy control in sharks suggests that ecological and physiological factors mediate the selective pressures acting on these traits along two major gradients, body size and habitat depth.

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Body Surface Area in Galeoid Sharks

Cited by 7 publications

References 6 publications

Ontogenetic morphometry of the brown smoothhound sharkMustelus henleiwith implications for ecology and evolution

Ontogenetic morphometry of the brown smoothhound sharkMustelus henleiwith implications for ecology and evolution

Hydrodynamic Characteristics of the Sailfish (Istiophorus platypterus) and Swordfish (Xiphias gladius) in Gliding Postures at Their Cruise Speeds

Physical trade-offs shape the evolution of buoyancy control in sharks

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