Scalloped hammerhead shark Sphyrna lewini, utilizes deep-water, hypoxic zone in the Gulf of California

A hammerhead shark Sphyrna lewini tracked for 74 days revealed an expansion of the range of vertical distribution for the species to include the extreme hypoxic environment of the oxygen minimum layer in the Gulf of California.     

Orygmatobothrium spp. (Cestoda: Tetraphyllidea) from triakid sharks in Argentina: redescription of Orygmatobothrium schmitti and description of a new species

Two species of Orygmatobothrium were found inhabiting triakid sharks collected from the coast of Buenos Aires Province, Argentina. Orygmatobothrium schmittii from Mustelus schmitti is redescribed, including new information on the microtrich pattern. Orygmatobothrium juani n. sp. from Mustelus fasciatus can be distinguished from all other species in the genus using the following combination of characters: worm length, number of proglottids, number of testes, testes distribution, size of eggs, ornamented egg shell, shape of bothridial cleft at level of the marginal accessory sucker, and the extension of vitelline follicles. Species in Orygmatobothrium share a common microtrich pattern with the distal bothridial surface covered with maisiform microtriches interspersed with filiform microtriches, a proximal bothridial surface covered with trifid microtriches, with a medial projection conspicuously larger than the lateral basal projections interspersed with filiform microtriches, an inner and outer surface of the accessory sucker and glandulomuscular organ covered with short filiform microtriches, the scolex proper and cephalic peduncle surface covered with bladelike microtriches, and the germinative zone and entire strobila covered with scutes formed by densely packed filiform microtriches. This general configuration is basically similar to the microtrich pattern described in species of Orectolobicestus and Paraorygmatobothrium.     

Surface ultrastructure of the elasmobranchia parasitizing <Emphasis Type="Italic">Grillotiella exilis</Emphasis> and <Emphasis Type="Italic">Pseudonybelinia odontacantha</Emphasis> (Trypanorhyncha,Cestoda)

The surface ultrastructure of two monotypic trypanorhynch genera is described based on new material of Grillotiella exilis (Linton, 1909) and type material of Pseudonybelinia odontacantha Dollfus 1966. In G. exilis, spiniform microtriches cover the bothrial surfaces and the anterior part of the pars vaginalis posterior to the bothria. Bifurcate microtriches adorn the bothrial margins, filiform microtriches the scolex peduncle, and capilliform microtriches the posterior scolex end. This microthrix pattern resembles that found in, e.g., Grillotia erinaceus (van Beneden, 1858), with the difference that the anterior part of the pars vaginalis is covered with a collar of multidigitate palmate microtriches. The position of Grillotiella within the Grillotiinae, Lacistorhynchidae is supported based on these data. The bothria and scolex peduncle of P. odontacantha are covered with acerosate and unciniform microtriches on the distal bothrial surface and capilliform microtriches on the scolex peduncle. Short filiform microtriches cover the appendix. The microthrix pattern resembles that of the Tentaculariidae but with unciniform and acerosate microtriches densely covering the entire distal bothrial surface. Tegumental grooves are present on the posterior bothrial margin. They can be distinguished from bothrial pits in otobothrioid trypanorhynchs in having similar unciniform microtriches compared to the other parts of the bothrial surface and in lacking any spiniform microtriches. With the absence of bothrial pits as characteristic for the otobothrioids and its characteristic microthrix pattern, P. odontacantha together with Paranybelinia otobothrioides Dollfus 1966, both belonging to the Paranybeliniidae change their position in the most recent system from the Otobothrioidea into the Tentacularioidea.     

Mother-offspring isotope fractionation in two species of placentatrophic sharks

Stable-isotope values of a scalloped hammerhead Sphyrna lewini and blacktip shark Carcharhinus limbatus and their respective embryos were analysed. Embryos of both species were enriched in δ(15) N compared to their mothers (0·82 and 0·88‰, respectively), but fractionation of δ(13) C varied. Embryonic S. lewini were enriched (1·00‰) in δ(13) C while C. limbatus were depleted (0·27‰) relative to their mothers.     

A study of the microtriches of adult Echinococcus granulosus by scanning electron microscopy

Thompson R. C. A., Houghton A. and Zaman V. 1982. A study of the microtriches of adult Echinococcus granulosus by scanning electron microscopy. International Journal for Parasitology12: 579–583. The microtriches in different regions of the scolex and strobila of sexually mature Echinococcus granulosus were examined using the scanning electron microscope. E. granulosus was found to possess two morphologically distinct types of microthrix. A cylindrical, slender filamentous type of microthrix which appeared to be flexible was restricted to the scolex. On the strobila, the only type of microthrix observed was a flattened blade-like form which appeared to be rigid for most of its length. The occurrence of two distinct types of microthrix in separate regions of the body of E. granulosus suggests that they may be involved in different functional activities.     

青岛近海路氏双髻鲨群体遗传学分析

研究采集了青岛近海23尾路氏双髻鲨(Sphyrna lewini), 通过线粒体DNA控制区片段对其遗传多样性进行分析。研究结果显示: 在23个个体的控制区序列上存在13个变异位点, 未检测到插入/缺失位点; 检测到7个单倍型, 其中3个为个体共享单倍型(Hap1、Hap3和Hap5), 4个为个体独有单倍型; 青岛近海路氏双髻鲨呈现中等水平的单倍型多样度和较低的核苷酸多样度; 与已报道的日照、霞浦群体间的遗传分化指数F_st值分别为–0.0571和–0.0328, 表明青岛群体与其他两个群体间不存在显著差异。以Sphyrna zygaena为外群构建NJ系统树显示本研究中7个单倍型共分成两支, 分别与来自太平洋、印度洋的单倍型类群聚类。中国近海的路氏双髻鲨作为一个具有较低遗传多样性的濒危物种, 其资源保护更应该引起足够的重视。     

Microthrix pattern of Pseudogilquinia thomasi (Palm, 2000) (Cestoda: Trypanorhyncha) and a review of surface ultrastructure within the family Lacistorhynchidae Guiart, 1927

The microthrix pattern of larvae of Pseudogilquinia thomasi (Palm, 2000) is described for the first time using scanning electron microscopy. The surface ultrastructure of this species consists of three main forms of microtriches: papilliform filitriches, acicular filitriches and quadridigitate to octadigitate palmate spinitriches. The bothria are covered with palmate spinitriches interspersed on some parts with papilliform filitriches. Palmate spinitriches with papilliform, acicular and capilliform filitriches adorn the pars vaginalis and at the anterior part of the pars bulbosa, there is a transition zone in which the palmate spinitriches are replaced by papilliform to acicular filitriches towards the end of the scolex. ANOVA tests with Duncan's post hoc analyses revealed that there are significant differences in the length of spinitriches and their prongs, whether on the surfaces of the bothria or on the surfaces of the scolex peduncle. Callitetrarhynchus gracilis Pintner, 1931 is the second lacistorhynchid species for which surfaces of the segments were examined and the occurrence of large structures called scutes are reported for the first time from this species. There were also significant differences in the base length as well as height of the scutes in different parts of the strobila. In addition to describing the surface ultrastructures of the two lacistorhynchid species, all the available information on the microtriches within the family Lacistorhynchidae is reviewed herein and generic diagnoses related to microtriches are amended. J. Morphol. 277:394–404, 2016. © 2015 Wiley Periodicals, Inc.     

Application of multiplex PCR approaches for shark molecular identification: feasibility and applications for fisheries management and conservation in the Eastern Tropical Pacific

Here we describe the application of new and existing multiplex PCR methodologies for shark species molecular identification. Four multiplex systems (group ID, thresher sharks, hammerhead sharks and miscellaneous shark) were employed with primers previously described and some designed in this study, which allow for species identification after running PCR products through an agarose gel. This system was implemented for samples (bodies and fins) collected from unidentified sharks landed in the port of Buenaventura and from confiscated tissues obtained from illegal fishing around the Malpelo Island Marine Protected Area, Pacific Coast of Colombia. This method has allowed reliable identification, to date, of 407 samples to the genus and/or species levels, most of them (380) identified as the pelagic thresher shark (Alopias pelagicus). Another seven samples were identified as scalloped hammerhead sharks (Sphyrna lewini). This is an easy-to-implement and reliable identification method that could even be used locally to monitor shark captures in the main fishing ports of developed and developing countries.     

Ultrastructure of the scolex of Orygmatobothrium schmittii (Cestoda: Phyllobothriidea)

The ultrastructure of the scolex of Orygmatobothrium schmittii (Cestoda: Phyllobothriidae) was studied using histochemistry, scanning, and transmission electron microscopy. The central bothridial structure resulted in a glandulomuscular organ formed by a mass of syncytial glands and radial muscles, with glycoprotein secretions potentially adhesive. Among the sensory receptors found on the scolex, a particular type was found surrounding the glandulomuscular organ, which might be related in the regulation of the secretions. The internal structure of the microtriches revealed a diversity of configurations according to their morphotype and distribution on the scolex. Microtriches with larger caps are thought to be useful for attachment purposes. In addition, the thick bounding membranes of the attachment organs and the circular musculature in the bothridia, seem to aid to the attachment of the scolex to the mucosa of the host.     

Maneuvering in juvenile carcharhinid and sphyrnid sharks: the role of the hammerhead shark cephalofoil

The peculiar head morphology of hammerhead sharks has spawned a variety of untested functional hypotheses. One of the most intuitively appealing ideas is that the anterior foil acts, as in canard-winged aircraft, to increase maneuverability. We tested this hypothesis by determining whether juveniles of two hammerhead species (Sphyrna tiburo and S. lewini) turn more sharply, more often, and with greater velocity than a juvenile carcharhinid shark (Carcharhinus plumbeus). Although the hammerheads were more maneuverable, further investigation revealed that they do not roll their body during turns, suggesting that the cephalofoil does not act as a steering wing. We also show that hammerhead sharks demonstrate greater lateral flexure in a turn than carcharhinids, and that this flexibility may be due to cross sectional shape rather than number of vertebrae.     

A Novel Mini-DNA Barcoding Assay to Identify Processed Fins from Internationally Protected Shark Species

There is a growing need to identify shark products in trade, in part due to the recent listing of five commercially important species on the Appendices of the Convention on International Trade in Endangered Species (CITES; porbeagle, Lamna nasus, oceanic whitetip, Carcharhinus longimanus scalloped hammerhead, Sphyrna lewini, smooth hammerhead, S. zygaena and great hammerhead S. mokarran) in addition to three species listed in the early part of this century (whale, Rhincodon typus, basking, Cetorhinus maximus, and white, Carcharodon carcharias). Shark fins are traded internationally to supply the Asian dried seafood market, in which they are used to make the luxury dish shark fin soup. Shark fins usually enter international trade with their skin still intact and can be identified using morphological characters or standard DNA-barcoding approaches. Once they reach Asia and are traded in this region the skin is removed and they are treated with chemicals that eliminate many key diagnostic characters and degrade their DNA (“processed fins”). Here, we present a validated mini-barcode assay based on partial sequences of the cytochrome oxidase I gene that can reliably identify the processed fins of seven of the eight CITES listed shark species. We also demonstrate that the assay can even frequently identify the species or genus of origin of shark fin soup (31 out of 50 samples).     

Discovery of a multispecies shark aggregation and parturition area in the Ba Estuary,Fiji Islands

Population declines in shark species have been reported on local and global scales, with overfishing, habitat destruction and climate change posing severe threats. The lack of species‐specific baseline data on ecology and distribution of many sharks, however, makes conservation measures challenging. Here, we present a fisheries‐independent shark survey from the Fiji Islands, where scientific knowledge on locally occurring elasmobranchs is largely still lacking despite the location's role as a shark hotspot in the Pacific. Juvenile shark abundance in the fishing grounds of the Ba Estuary (north‐western Viti Levu) was assessed with a gillnet‐ and longline‐based survey from December 2015 to April 2016. A total of 103 juvenile sharks identified as blacktip Carcharhinus limbatus (n = 57), scalloped hammerhead Sphyrna lewini (n = 35), and great hammerhead Sphyrna mokarran (n = 11) sharks were captured, tagged, and released. The condition of umbilical scars (68% open or semihealed), mean sizes of individuals (±SD) (C. limbatus: 66.5 ± 3.8 cm, S. lewini: 51.8 ± 4.8 cm, S. mokarran 77.4 ± 2.8 cm), and the presence of these species over recent years (based on fishermen interviews), suggest that the Ba Estuary area is a critical habitat for multiple species that are classified as “Near Threatened” or “Endangered.” Specifically, the area likely acts as a parturition ground over the studied period, and potentially as a subsequent nursery area. We identified subareas of high abundance and found that temperature, salinity and depth acted as small‐scale environmental drivers of shark abundance. The data suggests a tendency for species‐specific spatial use, both horizontally (i.e., between sampling areas) and vertically (i.e., across the water column). These results enhance the understanding of shark ecology in Fiji and provide a scientific basis for the implementation of local conservation strategies that contribute to the protection of these threatened species.     

The Species and Origin of Shark Fins in Taiwan’s Fishing Ports,Markets, and Customs Detention: A DNA Barcoding Analysis

The increasing consumption of shark products, along with the shark’s fishing vulnerabilities, has led to the decrease in certain shark populations. In this study we used a DNA barcoding method to identify the species of shark landings at fishing ports, shark fin products in retail stores, and shark fins detained by Taiwan customs. In total we identified 23, 24, and 14 species from 231 fishing landings, 316 fin products, and 113 detained shark fins, respectively. All the three sample sources were dominated by Prionace glauca, which accounted for more than 30% of the collected samples. Over 60% of the species identified in the fin products also appeared in the port landings, suggesting the domestic-dominance of shark fin products in Taiwan. However, international trade also contributes a certain proportion of the fin product markets, as four species identified from the shark fin products are not found in Taiwan’s waters, and some domestic-available species were also found in the customs-detained sample. In addition to the species identification, we also found geographical differentiation in the cox1 gene of the common thresher sharks (Alopias vulpinus), the pelagic thresher shark (A. pelagicus), the smooth hammerhead shark (Sphyrna zygaena), and the scalloped hammerhead shark (S. lewini). This result might allow fishing authorities to more effectively trace the origins as well as enforce the management and conservation of these sharks.     

Stomach content analysis of juvenile, scalloped hammerhead shark Sphyrna lewini captured off the coast of Mazatlán, Mexico

We quantified the diet of juvenile, scalloped hammerhead shark Sphyrna lewini in the area off Mazatlan, Sinaloa, Mexico, to understand their feeding ecology this shark. The prey species of Sphyrna lewini were identified and quantified from stomach content analysis. In addition, we determined the variations between genders. During two fishing seasons (2000–2001 and 2001–2002), we analyzed 232 stomachs, of which 85% contained food. The trophic spectrum was composed of three species of cephalopods, six of crustaceans and 19 species of fish from mainly pelagic and benthic habitats. According to the Index of Relative Importance (%IRI), the cephalopod Loliolopsis diomedeae with IRI = 18%, fish of the family Carangidae IRI = 25% and family Synodontidae IRI = 19% constituted the main prey in general. The trophic niche width was <0.4, which indicated that S. lewini juveniles in this area feed on a wide range of prey items, though they showed a preference for a few prey items.     

Prochristianella spinulifera n. sp. (Cestoda: Trypanorhyncha) from Australian dasyatid and rhinobatid rays

Prochristianella spinulifera n. sp. (Cestoda: Trypanorhyncha: Eutetrarhynchidae) is described from the spiral valves of the rays Rhinobatos typus (Rhinobatidae) and Himantura fai (Dasyatidae) from Heron Island, Queensland, Australia. The new species is distinguished from all congeners by the deltoid microtriches covering the anterior 80% of the scolex and the presence of a dorsoventrally elongate genital atrium. The species occurred in the anteriormost section of the spiral valve of R. typus. The orientation of the armature of this and other congeners is such that principal rows of hooks begin on the bothridial surface of the tentacle and end on the antibothridial surface.     

Microtriches of tetraphyllidean metacestodes from Western Mediterranean striped dolphins (Stenella coeruleoalba)

The tegumental structures of two types of tetraphyllidean plerocercoids and two types of merocercoids (Phyllobothrium delphini and Monorygma grimaldii) from Mediterranean striped dolphins, Stenella coeruleoalba, are described for the first time using scanning electron microscopy. The tegument of all of the specimens was fully covered with microtriches. Four basic types were found: filitriches, blade-like spinitriches of different sizes and shapes, cone-shaped spinitriches (with two parallel small projections of equal length at the apex), and crowned cylindrical spinitriches (with 6-7 small papillae forming a crown at the apex); the two latter types are newly described. The two types of plerocercoids had a similar morphology and distribution of microtriches; in addition, cilium-like projections appeared interspersed among the microtriches on the apical sucker, accessory suckers, and distal bothridial loculus. Merocercoids exhibited a greater variety of tegumental structures, especially on the distal bothridial loculus. Both merocercoid types had regularly spaced papillae or "buttons" on the accessory suckers and the distal bothridial loculus that were composed of a central cilium-like projection surrounded by numerous filitriches. However, crowned cylindrical spinitriches were specific to P. delphini and cone-shaped spinitriches were specific to M. grimaldii. Differences in the morphology and distribution of scolex microtriches of adult cestodes have been considered useful for species identification. A previous molecular study has suggested that P. delphini and M. grimaldii are actually different congeneric species. Our study has shown that significant differences in the morphology and distribution of microtriches occur between these species at the merocercoid stage.     

Redescription of <Emphasis Type="Italic">Cetorhinicola acanthocapax</Emphasis> Beveridge &; Campbell, 1988 (Cestoda: Trypanorhyncha) from the Basking Shark <Emphasis Type="Italic">Cetorhinus maximus</Emphasis> (Gunnerus)

Cetorhinicola acanthocapax Beveridge & Campbell, 1988 is redescribed based on adult specimens collected from a basking shark Cetorhinus maximus (Gunnerus) off the east coast of New Zealand. Both the mature and gravid segments are described for the first time, and the first scanning electron micrographs of the armature and scolex microtriches are provided. Novel features include the opening of the vagina anterior to the cirrus-sac and the extension of the vagina anterior to the cirrus-sac. Pectinate microtriches are present on the anterior quarter of the pars pedunculus scolecis scattered between filiform microtriches; the bothrial margins are covered with tridigitate microtriches, while the adherent surface of the bothria have pectinate microtriches. The additional morphological features described are consistent with a close association between Cetorhinicola Beveridge & Campbell, 1988 and the Eutetrarhynchoidea Guiart, 1927.     

Shallow water tidal flat use and associated specialized foraging behavior of the great hammerhead shark (Sphyrna mokarran)

Evidence suggests the great hammerhead shark, Sphyrna mokarran, is vulnerable to a variety of anthropogenic stressors, and is an understudied species of shark due to its cryptic nature and wide-ranging movements. While recognized as both a pelagic-coastal and a highly mobile predator, minimal anecdotal evidence exist describing shallow water habitat use by this species. This report describes six cases in which a great hammerhead shark utilizes an inshore shallow water flats environment (<1.5?m in depth), five of which involve prey capture. These observations permitted identification of two novel behaviors that may allow great hammerheads to inhabit these shallow habitats: a (1) prey-capture technique termed ‘grasp-turning’ that involves burst swimming at tight turning angles while grasping prey and (2) a post-predation recovery period whereby the shark maintains head-first orientation into the current that may facilitate respiration and prey consumption. These behavioral observations provide insights into the natural history of this species.