Climate change is an environmental emergency threatening species and ecosystems globally. Oceans have absorbed about 90% of anthropogenic heat and 20%-30% of the carbon emissions, resulting in ocean warming, acidification, deoxygenation, changes in ocean stratification and nutrient availability, and more severe extreme events. Given predictions of further changes, there is a critical need to understand how marine species will be affected.
View Article and Find Full Text PDFThe deep ocean is the last natural biodiversity refuge from the reach of human activities. Deepwater sharks and rays are among the most sensitive marine vertebrates to overexploitation. One-third of threatened deepwater sharks are targeted, and half the species targeted for the international liver-oil trade are threatened with extinction.
View Article and Find Full Text PDFSharks and rays are key functional components of coral reef ecosystems, yet many populations of a few species exhibit signs of depletion and local extinctions. The question is whether these declines forewarn of a global extinction crisis. We use IUCN Red List to quantify the status, trajectory, and threats to all coral reef sharks and rays worldwide.
View Article and Find Full Text PDFA curated database of shark and ray biological data is increasingly necessary both to support fisheries management and conservation efforts, and to test the generality of hypotheses of vertebrate macroecology and macroevolution. Sharks and rays are one of the most charismatic, evolutionary distinct, and threatened lineages of vertebrates, comprising around 1,250 species. To accelerate shark and ray conservation and science, we developed Sharkipedia as a curated open-source database and research initiative to make all published biological traits and population trends accessible to everyone.
View Article and Find Full Text PDFThe parasitic barnacle, , is a rare and evolutionary fascinating organism. Unlike most other filter-feeding barnacles, has evolved the capability to uptake nutrient from its host, exclusively parasitizing deepwater sharks of the families Etmopteridae and Pentanchidae. The physiological mechanisms involved in the uptake of nutrients from its host are not yet known.
View Article and Find Full Text PDFKnowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species.
View Article and Find Full Text PDFThe scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes-sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species were threatened.
View Article and Find Full Text PDFExtinctions on land are often inferred from sparse sightings over time, but this technique is ill-suited for wide-ranging species. We develop a space-for-time approach to track the spatial contraction and drivers of decline of sawfishes. These iconic and endangered shark-like rays were once found in warm, coastal waters of 90 nations and are now presumed extinct in more than half ( = 46).
View Article and Find Full Text PDFThis study describes and illustrates the jaws, teeth, and tooth microstructure of the Prickly Dogfish Oxynotus bruniensis. Detailed accounts of the dental morphology of O. bruniensis are rare and have not addressed the tissue arrangement or microstructure of the teeth.
View Article and Find Full Text PDFA single albino specimen of the lanternshark, Lucifer's dogfish (Etmopterus lucifer), is reported here. The specimen was found among museum collections, having been captured near Cape Palliser, off the North Island of New Zealand in 1984. Morphometrics are reported, and with no retainment of pigmentation, the specimen is considered a complete albino.
View Article and Find Full Text PDFThe barnacle Anelasma squalicola is a marine epibiont found on members of the species-rich, deep-sea lantern shark family Etmopteridae (Figure 1A) but is unlike any other epibiotic thoracian barnacles [1]. While many barnacle species are associated with various marine animals including turtles and whales, with the exception of Anelasma these all retain a filter-feeding lifestyle and have a commensal relationship with their host; despite often being deeply embedded in the dermis, no other species has been reported as feeding on its host. Although Anelasma is fully equipped with cirri (thoracic appendages), these are no longer used for filter feeding [1].
View Article and Find Full Text PDFJustin Rizzari and Brittany Finucci introduce elephant fish, a small group of shark relatives.
View Article and Find Full Text PDFAn integrated taxonomic approach, combining both morphological and molecular data, was adopted to investigate the Hydrolagus lemures-ogilbyi group in the Indo-Australian region. Single mitochondrial markers (CO1 and NADH2) provided evidence supporting the separation of four distinct species in this group. However, detailed morphological data collected from specimens from across their range failed to find any consistent differences, and many features previously considered to be diagnostic were found to be variable.
View Article and Find Full Text PDFA palatal organ, possibly used for food sorting and processing, has previously been identified among the vomerine toothplates of the chimaeroid Chimaera monstrosa. In this study, the palatal organ was described in six additional species, confirming it is a widespread trait among holocephalans. It is proposed that this palatal structure, which appears to differ in shape according to each chimaeroid's degree of durophagy and is not homologous to the palatal structure described in teleosts, be hereby referred to as Vacchi's organ.
View Article and Find Full Text PDFChimaera carophila (n = 45) and Hydrolagus homonycteris (n = 11), two deep-sea chimaerids rarely caught in the waters off New Zealand, were collected from research trawl catches and commercial fishery catches around New Zealand at depths between 400 and 1300 m, between 2014 and 2016. Additional preserved specimens of both species (n = 58) from museum collections were analysed for size, sex and maturity. External assessment of male claspers and a combination of internal assessments of female gonad mass and oviducal gland width, were used to determine maturity.
View Article and Find Full Text PDFThe reproductive biology and diet of prickly dogfish Oxynotus bruniensis, a deep-sea elasmobranch, endemic to the outer continental and insular shelves of southern Australia and New Zealand, and caught as by-catch in demersal fisheries, are described from specimens caught in New Zealand waters. A total of 53 specimens were obtained from research surveys and commercial fisheries, including juveniles and adults ranging in size from 33·5 to 75·6 cm total length (L ). Estimated size-at-maturity was 54·7 cm L in males and 64·0 cm L in females.
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