Ontogeny of Squamation in Swordfish, Xiphias gladius

Govoni, John J.; West, Mari; Zivotofsky, D.; Zivotofsky, Ari Z.; Bowser, Paul R.; Collette, Bruce B.

doi:10.1643/cg-03-126r2

Cited by 8 publications

(9 citation statements)

References 13 publications

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“…On the other hand, the protrusions observed on the swordfish skin are tiny and much smaller than those on the sailfish skin (see Figure 1 ). They are the tips of the scales whose major parts are immersed in the dermis [8] , [11] . The drag on the swordfish with smooth skin is decreased by 1∼4% than that of the original swordfish.…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, the skin types of the sailfish and swordfish are very different from each other. The adult sailfish has a number of V-shaped protrusions (bony scales) on its skin [8] , [31] , but the skin of adult swordfish is apparently smooth because the scales are deeply embedded within the dermis [8] , [11] . The role of the V-shaped protrusions on the sailfish skin was investigated for the purpose of drag reduction by Sagong et al [31] .…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

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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“…Arata (1954) mentions certain conflicting reports of scale development from previous studies and concludes that scales must be lost at some stage beyond the fish reaching four feet (1.22 m) in length. As noted, Potthoff and Kelley's (1982) measurements demonstrate the presence of scales on a specimen 668 mm in length, and more recently, Govoni et al (2004) show photomicrographic evidence of scales in an adult specimen, 3300 mm in length. Govoni et al (2004) state that some of the confusion surrounding the presence of scales stems from the fact that the dermis above the scales thickens as the swordfish ages, which buries all but the tips of the spines on the scales.…”

Section: Introductionmentioning

confidence: 79%

High-resolution measurements of swordfish skin surface roughness

Stewart,

Cameron,

Thunert

et al. 2023

Bioinspir. Biomim.

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The three-dimensional morphology of swordfish skin roughness remains poorly understood. Subsequently, its importance to the overall physiology and hydrodynamic performance of the swordfish is yet to be determined. This is at least partly attributable to the inherent difficulty in making the required measurements of these complex biological surfaces. To address this, here two sets of novel high-resolution measurements of swordfish skin, obtained using a modular optical coherence tomography system and a gel-based stereo-profilometer, are reported and compared. Both techniques are shown to provide three-dimensional morphological data at micron-scale resolution. The results indicate that the skin surface is populated with spiny roughness elements, typically elongated in the streamwise direction, in groups of up to six, and in good agreement with previously reported information based on coarser measurements. In addition, our data also provide new information on the spatial distribution and variability of these roughness features. Two approaches, one continuous and another discrete, are used to derive various topographical metrics that characterize the surface texture of the skin. The information provided here can be used to develop statistically representative synthetic models of swordfish skin roughness.

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“…For some time, there was confusion in the literature regarding the presence of scales in adult swordfish Xiphias gladius L. 1758 (Nakamura et al, 1951;Potthoff & Kelley, 1982;Collette et al, 1984). Govoni et al (2004) showed that scales are indeed present in adult X. gladius. Thickening of the dermis during ontogeny results in scales of adults becoming more deeply embedded in the dermis, with only the tips of the spines protruding through the dermis.…”

Section: N T E R S P E C I F I C C O M Pa R I S O N Smentioning

confidence: 96%

Comparative morphology of the scales of roundscale spearfish Tetrapturus georgii and white marlin Kajikia albida

Loose

Hilton

Graves

2017

Journal of Fish Biology

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The comparative morphology of the scales of roundscale spearfish Tetrapturus georgii and white marlin Kajikia albida was investigated. In addition, variation in scale morphology across different body regions within each species was analysed. Although considerable morphological variation was observed among scales from different body regions in both species, scales of K. albida generally have pointed anterior ends, fewer posterior points and are more heavily imbricated than those of T. georgii, which are frequently rounded anteriorly, often have many posterior points and are separated farther within the skin. In all sampled body regions and individuals, scales of T. georgii are significantly broader and have a lower length-to-width aspect ratio than those of K. albida. Superficial to the scales are denticular plates, which are ossified formations occurring on the surface layer of the epidermis; these were observed and described for T. georgii, K. albida and blue marlin Makaira nigricans. Detailed scale descriptions allow for a more accurate characterization of the variation within and differences between these two species and could potentially be a valuable tool for investigating istiophorid systematics.

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Ontogeny of Squamation in Swordfish, Xiphias gladius

Cited by 8 publications

References 13 publications

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

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

High-resolution measurements of swordfish skin surface roughness

Comparative morphology of the scales of roundscale spearfish Tetrapturus georgii and white marlin Kajikia albida

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