Dermal denticle shedding rates vary between two captive shark species

2021 ◽  
Author(s):  
EM Dillon ◽  
A Bagla ◽  
KD Plioplys ◽  
DJ McCauley ◽  
KD Lafferty ◽  
...  
Keyword(s):  
Shark Species ◽  
Dermal Denticle

scholarly journals Dermal denticle diversity in sharks: novel patterns on the interbranchial skin

2021 ◽  
Author(s):  
Molly K Gabler-Smith ◽  
Dylan K Wainwright ◽  
Greta A Wong ◽  
George V Lauder
Keyword(s):  
Surface Topography ◽  
Fluid Motion ◽  
Leading Edge ◽  
Shark Species ◽  
Trailing Edge ◽  
Future Studies ◽  
Body Regions ◽  
Dermal Denticle ◽  
The Relationship

Abstract Shark skin is covered in dermal denticles – tooth-like structures consisting of enameloid, dentine, and a central pulp cavity. Previous studies have demonstrated differences in denticle morphology both among species and across different body regions within a species, including one report of extreme morphological variation within a 1 cm distance on the skin covering the branchial pouches, a region termed “interbranchial skin”. We used gel-based profilometry, histology, and scanning electron microscopy to quantify differences in denticle morphology and surface topography of interbranchial skin denticles among 13 species of sharks to better understand the surface structure of this region. We show that 1) interbranchial skin denticles differ across shark species, and 2) denticles on the leading edge of the skin covering each gill pouch have different morphology and surface topography compared to denticles on the trailing edge. Across all species studied, there were significant differences in denticle length (P = 0.01) and width (P = 0.002), with shorter and wider leading edge denticles compared to trailing edge denticles. Surface skew was also higher in leading edge denticles (P = 0.009), though most values were still negative, indicating more valleys than peaks. Overall, leading edge denticles were smoother-edged than trailing edge denticles in all of the species studied. These data suggest two hypotheses: 1) smoother-edged leading edge denticles protect the previous gill flap from abrasion during respiration, and 2) ridged denticle morphology at the trailing edge might alter water turbulence exiting branchial pouches after passing over the gills. Future studies will focus on determining the relationship between denticle morphology and water flow by visualizing fluid motion over interbranchial denticles during in vivo respiration.

A new Triodus shark species (Xenacanthidae, Xenacanthiformes) from the lowermost Permian of France and its paleobiogeographic implications

2021 ◽  
pp. e1926470
Author(s):  
Vincent Luccisano ◽  
Alan Pradel ◽  
Romain Amiot ◽  
Georges Gand ◽  
J.-Sebastien Steyer ◽  
...  
Keyword(s):  
Shark Species

scholarly journals Development of an environmental DNA assay for detecting multiple shark species involved in human–shark conflicts in Australia

2021 ◽  
Author(s):  
Anthony Rooyen ◽  
Adam D. Miller ◽  
Zach Clark ◽  
Craig D. H. Sherman ◽  
Paul A. Butcher ◽  
...  
Keyword(s):  
Environmental Dna ◽  
Shark Species ◽  
Dna Assay

The ichnospecies Linichnus bromleyi on a Miocene baleen whale radius preserving multiple shark bite-shake traces suggests scavenging

2021 ◽  
Vol 21 (17) ◽  
pp. 391-398
Author(s):  
Stephen J. Godfrey ◽  
Annie J. Lowry
Keyword(s):  
Trace Fossil ◽  
Shark Species ◽  
Baleen Whale

An isolated Miocene baleen whale left radius was marked repeatedly by shark bite-shake traces. The radius probably derives from the Plum Point Member of the Calvert Formation, Calvert Cliffs, Calvert County, Maryland, U.S.A. At least three successive bite-shake traces, made by multiple teeth, marking the radius are attributed to the trace fossil Linichnus bromleyi. These bite-shake trace consisting of shallow, thin arching gouges on a radius, likely indicates scavenging rather than active predation. The most likely means of producing the bundle of L. bromleyi within each of the three sets of traces would be through repeated biting as the shark re-positioned the prey in its mouth or, perhaps, by a shark species with multiple functional teeth within its tooth row. If the bite traces were produced by a non-serrated tooth (as they appear to have been), then the most likely candidate would be Carcharodon hastalis.

Bycatch and landings of young of the year sharks in the Malaysian South China Sea: implications for conservation

2015 ◽  
Vol 8 ◽  
Author(s):  
Azie Azri ◽  
Takaomi Arai
Keyword(s):  
South China Sea ◽  
South China ◽  
Fishing Gear ◽  
Shark Species ◽  
Vulnerable Species ◽  
Critical Levels ◽  
Sphyrna Lewini ◽  
China Sea ◽  
Young Of The Year ◽  
Near Threatened

A total of 104 sharks were landed at fishing ports in the Malaysian South China Sea between 30 October and 24 December 2014, comprising the four families, Carcharhinidae, Hemiscylliidae, Sphyrnidae and Scyliorhinidae, and 11 of these shark species were examined. Measurements of size and weight were different and varied among species, ranging from 0.1 to 7.5 kg in body weight and from 31.1 to 105 cm in total length. Five of the 11 sharks,Carcharhinus sealei, Loxodon macrorhinus, Rhizoprionodon acutus, Hemigaleus microstomaandSphyrna lewini, were in the range of, or even less than, the lengths of those measured at birth in previous reports. The results suggest that these sharks were born just before they were landed.Sphyrna lewiniand H.microstomaare categorized as Endangered and Vulnerable species, respectively, and other sharks included in the landings are also categorized as Near Threatened. Thus, the current fishing methods could lead to critical levels of shark species in these waters, and even the future extinction of species. An improvement in the species selectiveness of fishing gear is needed to protect and conserve sharks in the area.

scholarly journals Diet of three shark species in the Ecuadorian Pacific, Carcharhinus falciformis, Carcharhinus limbatus and Nasolamia velox

2017 ◽  
Vol 98 (4) ◽  
pp. 927-935 ◽  
Author(s):  
Colombo Estupiñán-Montaño ◽  
Fabian Pacheco-Triviño ◽  
Luis G. Cedeño-Figueroa ◽  
Felipe Galván-Magaña ◽  
Jose F. Estupiñán-Ortiz
Keyword(s):  
Stomach Contents ◽  
Thunnus Albacares ◽  
Shark Species ◽  
Dosidicus Gigas ◽  
Katsuwonus Pelamis ◽  
Carcharhinus Limbatus ◽  
Lack Of Information ◽  
Bony Fishes ◽  
Carcharhinus Falciformis ◽  
Conservation Plans

We analysed the stomach contents of 69 silky sharks Carcharhinus falciformis, 44 blacktip sharks Carcharhinus limbatus and 24 whitenose sharks Nasolamia velox caught in the Ecuadorian Pacific from August 2003 to December 2004. Prey included bony fishes, elasmobranchs, molluscs, crustaceans and turtles, with bony fishes being the most important to the diets of all three sharks, suggesting they are piscivorous predators. Based on the index of relative importance, the C. falciformis diet includes Thunnus albacares, Thunnus sp. and Auxis thazard, as well as some squid, fish and turtles. Similarly, the C. limbatus diet was dominated by T. albacares, Exocoetus monocirrhus, A. thazard, Katsuwonus pelamis, members of the Ophichthidae family and other elasmobranchs. Meanwhile, N. velox consumed mainly Dosidicus gigas, Larimus argenteus, Cynoscion sp. and Lophiodes spilurus. There is little competition for food between these tertiary carnivores: C. limbatus prefers prey from coastal-oceanic habitats; C. falciformis consumes mostly oceanic prey and N. velox focuses on prey from coastal habitats. The lack of information on the biology of sharks in Ecuador hinders the development of appropriate management and conservation plans to protect shark resources. This study increases our knowledge and understanding of sharks in Ecuador, thus contributing to their conservation.

Long-term migration patterns and bisexual philopatry in a benthic shark species

2017 ◽  
Vol 68 (8) ◽  
pp. 1414 ◽  
Author(s):  
Nathan Charles Bass ◽  
Johann Mourier ◽  
Nathan A. Knott ◽  
Joanna Day ◽  
Tristan Guttridge ◽  
...  
Keyword(s):  
Management Strategies ◽  
Movement Patterns ◽  
Conclusive Evidence ◽  
Migration Route ◽  
Shark Species ◽  
Apex Predators ◽  
Arrival Times ◽  
And Bisexual ◽  
Australian Coastline ◽  
Port Jackson

Knowledge of the broad-scale movement patterns of sharks is essential to developing effective management strategies. Currently there is a large bias in studies focusing on species that are either large apex predators or found in tropical to subtropical regions. There is limited knowledge of the movements and migrations of benthic and temperate shark species. The present study used passive acoustic telemetry to investigate the movement patterns of a benthic shark species, the Port Jackson shark (Heterodontus portusjacksoni). Individuals were tagged with acoustic transmitters between 2012 and 2014 and their movements were monitored within Jervis Bay and along the east Australian coastline for up to 4 years. Male and female Port Jackson sharks demonstrated high levels of philopatry to both Jervis Bay and their tagging location across multiple years. Although males and females did not differ in their arrival times, females departed from Jervis Bay later than males. Approximately half the tagged individuals migrated in a southward direction, with individuals being detected at Narooma, Bass Strait and Cape Barron Island. This study provides conclusive evidence of bisexual philopatry in a benthic temperate shark species, confirming previous hypotheses, and presents the most detailed migration route for Port Jackson sharks to date.

scholarly journals CAPABILITY OF MITOCHONDRIA DNA D-LOOP MARKERS FOR SHARK SPECIES IDENTIFICATION

2017 ◽  
Vol 7 (1) ◽  
pp. 62
Author(s):  
Estu Nugroho
Keyword(s):  
Species Identification ◽  
Shark Species ◽  
Loop Region ◽  
D Loop ◽  
Mitochondria Dna

ldentification of dry-fin shark was conducted by mitochondria DNA (mtDNA) D-loop markers. Eighteen of thiity samples have been successfully amplified the mtDNA D-loop region.

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