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Elasmobranch

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https://www.readbyqxmd.com/read/29118464/eocene-squalomorph-sharks-chondrichthyes-elasmobranchii-from-antarctica
#1
Andrea Engelbrecht, Thomas Mörs, Marcelo A Reguero, Jürgen Kriwet
Rare remains of predominantly deep-water sharks of the families Hexanchidae, Squalidae, Dalatiidae, Centrophoridae, and Squatinidae are described from the Eocene La Meseta Formation, Seymour Island, Antarctic Peninsula, which has yielded the most abundant chondrichthyan assemblage from the Southern Hemisphere to date. Previously described representatives of Hexanchus sp., Squalus weltoni, Squalus woodburnei, Centrophorus sp., and Squatina sp. are confirmed and dental variations are documented. Although the teeth of Squatina sp...
October 2017: Journal of South American Earth Sciences
https://www.readbyqxmd.com/read/29056144/sharks-in-captivity-the-role-of-husbandry-breeding-education-and-citizen-science-in-shark-conservation
#2
Michael Grassmann, Bryan McNeil, Jim Wharton
The role of public aquariums in promoting conservation has changed substantially over the decades, evolving from entertainment attractions to educational and research centres. In many facilities, larger sharks are an essential part of the collection and represent one of the biggest draws for the public. Displaying healthy elasmobranchs comes with many challenges, but improvements in husbandry techniques have enabled aquariums to have success with a variety of species. The establishment of organisations such as the Association of Zoos and Aquariums, and the completion of texts like the Elasmobranch Husbandry Manual, has helped set high standards of care for sharks in captivity and promoted international conservation efforts...
2017: Advances in Marine Biology
https://www.readbyqxmd.com/read/29056143/an-introduction-to-modelling-abundance-and-life-history-parameters-in-shark-populations
#3
Dovi Kacev, Timothy J Sippel, Michael J Kinney, Sebastián A Pardo, Christopher G Mull
Elasmobranchs play critically important ecological roles throughout the world's oceans, yet in many cases, their slow life histories and interactions with fisheries makes them particularly susceptible to exploitation. Management for these species requires robust scientific input, and mathematical models are the backbone of science-based management. In this chapter, we provide an introductory overview of the use of mathematical models to estimate shark abundance. First, we discuss life history models that are used to understand the basic biology of elasmobranchs...
2017: Advances in Marine Biology
https://www.readbyqxmd.com/read/29044046/locally-extensive-meningoencephalitis-caused-by-miamiensis-avidus-syn-philasterides-dicentrarchi-in-a-zebra-shark
#4
Wen-Ta Li, Chieh Lo, Chen-Yi Su, Hsuan Kuo, Susanne Je-Han Lin, Hui-Wei Chang, Victor Fei Pang, Chian-Ren Jeng
Scuticociliatosis, caused by ciliated protozoa in the subclass Scuticociliatia of the phylum Ciliophora, can cause fatal disease in teleost fish species. However, information on scuticociliatosis in elasmobranchs is still scarce. In this report, we describe a case of locally extensive meningoencephalitis caused by Miamiensis avidus (syn. Philasterides dicentrarchi) in a 2 yr old captive zebra shark Stegostoma fasciatum. Granulocytic meningoencephalitis was observed through histological assessment. Inflammation was confined to the ventral aspect of the brain with a large number of ciliated protozoa, transforming into non-suppurative meningitis in the lateral aspect, and gradually vanished in the dorsal aspect...
October 18, 2017: Diseases of Aquatic Organisms
https://www.readbyqxmd.com/read/29034467/first-insights-into-the-function-of-the-sawshark-rostrum-through-examination-of-rostral-tooth-microwear
#5
R J Nevatte, B E Wueringer, D E Jacob, J M Park, J E Williamson
Potential roles of the rostrum of sawsharks (Pristiophoridae), including predation and self-defence, were assessed through a variety of inferential methods. Comparison of microwear on the surface of the rostral teeth of sawsharks and sawfishes (Pristidae) show that microwear patterns are alike and suggest that the elongate rostra in these two elasmobranch families are used for a similar purpose (predation). Raman spectroscopy indicates that the rostral teeth of both sawsharks and sawfishes are composed of hydroxyapatite, but differ in their collagen content...
October 16, 2017: Journal of Fish Biology
https://www.readbyqxmd.com/read/29023719/natural-variability-and-effects-of-cleaning-and-storage-procedures-on-vertebral-chemistry-of-the-blacktip-shark-carcharhinus-limbatus
#6
J P Lewis, W F Patterson, J K Carlson
Key methodological assumptions regarding the degree of natural variability and influence of sample handling and storage of elasmobranch vertebral chemistry were assessed using laser-ablation inductively coupled plasma mass spectrometry. Vertebral chemistry of juvenile blacktip sharks Carcharhinus limbatus was examined to identify whether differences existed among different regions of the vertebral column, between thoracic vertebrae of individual fish or within individual vertebrae. Additionally, the effects of bleach exposure and storage in ethanol on vertebral chemistry were compared...
October 10, 2017: Journal of Fish Biology
https://www.readbyqxmd.com/read/29023598/the-greenland-shark-somniosus-microcephalus-hemoglobins-and-ligand-binding-properties
#7
Roberta Russo, Daniela Giordano, Gianluca Paredi, Francesco Marchesani, Lisa Milazzo, Giovanna Altomonte, Pietro Del Canale, Stefania Abbruzzetti, Paolo Ascenzi, Guido di Prisco, Cristiano Viappiani, Angela Fago, Stefano Bruno, Giulietta Smulevich, Cinzia Verde
A large amount of data is currently available on the adaptive mechanisms of polar bony fish hemoglobins, but structural information on those of cartilaginous species is scarce. This study presents the first characterisation of the hemoglobin system of one of the longest-living vertebrate species (392 ± 120 years), the Arctic shark Somniosus microcephalus. Three major hemoglobins are found in its red blood cells and are made of two copies of the same α globin combined with two copies of three very similar β subunits...
2017: PloS One
https://www.readbyqxmd.com/read/28989770/large-batoid-fishes-frequently-consume-stingrays-despite-skeletal-damage
#8
Mason N Dean, Joseph J Bizzarro, Brett Clark, Charlie J Underwood, Zerina Johanson
The shapes of vertebrate teeth are often used as hallmarks of diet. Here, however, we demonstrate evidence of frequent piscivory by cartilaginous fishes with pebble-like teeth that are typically associated with durophagy, the eating of hard-shelled prey. High-resolution micro-computed tomography observation of a jaw specimen from one batoid species and visual investigation of those of two additional species reveal large numbers of embedded stingray spines, arguing that stingray predation of a scale rivalling that of the largest carnivorous sharks may not be uncommon for large, predatory batoids with rounded, non-cutting dentition...
September 2017: Royal Society Open Science
https://www.readbyqxmd.com/read/28972451/differential-effects-of-temperature-on-oxygen-consumption-and-branchial-fluxes-of-urea-ammonia-and-water-in-the-dogfish-shark-squalus-acanthias-suckleyi
#9
Marina Giacomin, Patricia M Schulte, Chris M Wood
Environmental temperature can greatly influence the homeostasis of ectotherms through its effects on biochemical reactions and whole-animal physiology. Elasmobranchs tend to be N limited and are osmoconformers, retaining ammonia and urea-N at the gills and using the latter as a key osmolyte to maintain high blood osmolality. However, the effects of temperature on these key processes remain largely unknown. We evaluated the effects of acute exposure to different temperatures (7°, 12°, 15°, 18°, 22°C) on oxygen consumption, ammonia, urea-N, and diffusive water fluxes at the gills of Squalus acanthias suckleyi...
November 2017: Physiological and Biochemical Zoology: PBZ
https://www.readbyqxmd.com/read/28970537/migratory-appendicular-muscles-precursor-cells-in-the-common-ancestor-to-all-vertebrates
#10
Eri Okamoto, Rie Kusakabe, Shigehiro Kuraku, Susumu Hyodo, Alexandre Robert-Moreno, Koh Onimaru, James Sharpe, Shigeru Kuratani, Mikiko Tanaka
In amniote embryos, skeletal muscles in the trunk are derived from epithelial dermomyotomes, the ventral margin of which extends ventrally to form body wall muscles. At limb levels, ventral dermomyotomes also generate limb-muscle precursors, an Lbx1-positive cell population that originates from the dermomyotome and migrates distally into the limb bud. In elasmobranchs, however, muscles in the paired fins were believed to be formed by direct somitic extension, a developmental pattern used by the amniote body wall muscles...
October 2, 2017: Nature ecology & evolution
https://www.readbyqxmd.com/read/28940897/effects-of-sample-cleaning-and-storage-on-the-elemental-composition-of-shark-vertebrae
#11
John A Mohan, Thomas C TinHan, Nathan R Miller, R J David Wells
RATIONALE: Application of vertebral chemistry in elasmobranchs has the potential to progress our understanding of individual migration patterns and population dynamics. However, the influence of handling artifacts such as sample cleaning and storage on vertebral chemistry is unclear and requires experimental investigation. METHODS: Vertebrae centra from blacktip sharks (Carcharhinus limbatus) were cleaned with bleach (NaOCl) for five minutes (m), 1 hour (h) and 24 (h) in a cleaning experiment and stored frozen, in 70% ethanol, and 10% formalin treatments for 20 days in a storage experiment...
September 20, 2017: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/28935583/role-of-elasmobranchs-and-holocephalans-in-understanding-peptide-evolution-in-the-vertebrates-lessons-learned-from-gonadotropin-releasing-hormone-gnrh-and-corticotropin-releasing-factor-crf-phylogenies
#12
REVIEW
David A Lovejoy, Ola M Michalec, David W Hogg, David I Wosnick
The cartilaginous fishes (Class Chondrichthyes) comprise two morphologically distinct subclasses; Elasmobranchii and Holocephali. Evidence indicates early divergence of these subclasses, suggesting monophyly of their lineage. However, such a phylogenetic understanding is not yet developed within two highly conserved peptide lineages, GnRH and CRF. Various GnRH forms exist across the Chondrichthyes. Although 4-7 immunoreactive forms have been described in Elasmobranchii, only one has been elucidated in Holocephali...
September 18, 2017: General and Comparative Endocrinology
https://www.readbyqxmd.com/read/28924159/live-bearing-without-placenta-physical-estimation-indicates-the-high-oxygen-supplying-ability-of-white-shark-uterus-to-the-embryo
#13
Taketeru Tomita, Ryo Nozu, Masaru Nakamura, Shohei Matsuzaki, Kei Miyamoto, Keiichi Sato
One of the mysteries of shark aplacental viviparity is the ability of the embryos to acquire oxygen from their mothers without a placental connection. It has been assumed that embryonic respiration in aplacental viviparous shark depends on oxygen from the uterine wall, although this hypothesis has not been confirmed quantitatively. Morphological observations of the uterine wall of white shark (Carcharodon carcharias) provided the first quantitative evidence to support the ability of the uterus to supply ample oxygen to the embryo of viviparous elasmobranchs...
September 18, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28923557/a-molecular-approach-towards-taxonomic-identification-of-elasmobranch-species-from-maltese-fisheries-landings
#14
Adriana Vella, Noel Vella, Sarah Schembri
The mitochondrial genome, through the application of DNA barcoding, provides a powerful tool for identifying species even when specimens are either incomplete or belong to species that exhibit cryptic diversity. In fisheries management accurate identification of whole or part of the specimens landed is a fundamental requirement for the conservation of species affected directly or indirectly by the fisheries activities. In this study cytochrome c oxidase subunit I (COI) and NADH dehydrogenase subunit 2 (ND2) sequences were used to genetically distinguish 36 elasmobranch species collected from Maltese (Central Mediterranean) commercial fisheries landings...
September 8, 2017: Marine Genomics
https://www.readbyqxmd.com/read/28923317/calcified-cartilage-or-bone-collagens-in-the-tessellated-endoskeletons-of-cartilaginous-fish-sharks-and-rays
#15
Ronald Seidel, Michael Blumer, Elisabeth-Judith Pechriggl, Kady Lyons, Brian K Hall, Peter Fratzl, James C Weaver, Mason N Dean
The primary skeletal tissue in elasmobranchs -sharks, rays and relatives- is cartilage, forming both embryonic and adult endoskeletons. Only the skeletal surface calcifies, exhibiting mineralized tiles (tesserae) sandwiched between a cartilage core and overlying fibrous perichondrium. These two tissues are based on different collagens (Coll II and I, respectively), fueling a long-standing debate as to whether tesserae are more like calcified cartilage or bone (Coll 1-based) in their matrix composition. We demonstrate that stingray (Urobatis halleri) tesserae are bipartite, having an upper Coll I-based 'cap' that merges into a lower Coll II-based 'body' zone, although tesserae are surrounded by cartilage...
October 2017: Journal of Structural Biology
https://www.readbyqxmd.com/read/28887553/insight-into-shark-magnetic-field-perception-from-empirical-observations
#16
James M Anderson, Tamrynn M Clegg, Luisa V M V Q Véras, Kim N Holland
Elasmobranch fishes are among a broad range of taxa believed to gain positional information and navigate using the earth's magnetic field, yet in sharks, much remains uncertain regarding the sensory receptors and pathways involved, or the exact nature of perceived stimuli. Captive sandbar sharks, Carcharhinus plumbeus were conditioned to respond to presentation of a magnetic stimulus by seeking out a target in anticipation of reward (food). Sharks in the study demonstrated strong responses to magnetic stimuli, making significantly more approaches to the target (p = < 0...
September 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28882215/review-of-current-conservation-genetic-analyses-of-northeast-pacific-sharks
#17
Shawn E Larson, Toby S Daly-Engel, Nicole M Phillips
Conservation genetics is an applied science that utilizes molecular tools to help solve problems in species conservation and management. It is an interdisciplinary specialty in which scientists apply the study of genetics in conjunction with traditional ecological fieldwork and other techniques to explore molecular variation, population boundaries, and evolutionary relationships with the goal of enabling resource managers to better protect biodiversity and identify unique populations. Several shark species in the northeast Pacific (NEP) have been studied using conservation genetics techniques, which are discussed here...
2017: Advances in Marine Biology
https://www.readbyqxmd.com/read/28882214/age-and-growth-of-elasmobranchs-and-applications-to-fisheries-management-and-conservation-in-the-northeast-pacific-ocean
#18
Mary E Matta, Cindy A Tribuzio, David A Ebert, Kenneth J Goldman, Christopher M Gburski
In addition to being an academic endeavour, the practical purpose of conducting age and growth studies on fishes is to provide biological data to stock assessment scientists and fisheries managers so they may better understand population demographics and manage exploitation rates. Age and size data are used to build growth models, which are a critical component of stock assessments. Though age determination of elasmobranchs in the northeast Pacific Ocean (NEP) began in the 1930s, the field has evolved substantially in recent years, allowing scientists to incorporate age data into assessments for more species than ever before...
2017: Advances in Marine Biology
https://www.readbyqxmd.com/read/28882213/stable-isotope-applications-for-understanding-shark-ecology-in-the-northeast-pacific-ocean
#19
Jonathan C P Reum, Gregory D Williams, Chris J Harvey
Stable isotopes are used to address a wide range of ecological questions and can help researchers and managers better understand the movement and trophic ecology of sharks. Here, we review how shark studies from the Northeast Pacific Ocean (NEP) have employed stable isotopes to estimate trophic level and diet composition and infer movement and habitat-use patterns. To date, the number of NEP shark studies that have used stable isotopes is limited, suggesting that the approach is underutilized. To aid shark researchers in understanding the strengths and limitations of the approach, we provide a brief overview of carbon and nitrogen stable isotope trophic discrimination properties (e...
2017: Advances in Marine Biology
https://www.readbyqxmd.com/read/28841535/female-reproductive-traits-of-a-commercially-exploited-skate-atlantoraja-platana-g%C3%A3-nther-1880-chondrichthyes-rajidae-ovarian-morphology-gametogenesis-and-microscopic-verification-of-maturity-criteria
#20
A C Moya, A Wehitt, M C Díaz Andrade, E E Di Giacomo, E J Galíndez
Atlantoraja platana is an endemic species of the Southwest Atlantic Ocean, and is one of the most captured by the local bottom trawl industrial fisheries. In this work, the microscopic architecture of mature female's gonads and the dynamics of follicle development are studied as a contribution to raise awareness of reproductive biology of the species. Folliculogenesis depicts the same histologic pattern as in other Elasmobranchs. Follicles in different degrees of maturation coexist in mature animals. The oogonia were only found in immature individuals...
August 12, 2017: Micron: the International Research and Review Journal for Microscopy
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