Freshwater Shark Research Articles

Freshwater shark teeth (Family Lonchidiidae) from the Middle-Upper Triassic (Ladinian-Carnian) Paramillo Formation in the Mendoza Precordillera, Argentina

ABSTRACTA collection of over 550 elasmobranch teeth (Family Lonchidiidae) were obtained from fresh water fluvial deposits of the Middle–Upper Triassic (Ladinian–Carnian) Paramillo Formation, in northwestern Mendoza Province, Argentina. The new hybodontid species, Lonchidion paramilloensis, sp. nov., solely based on teeth, is within a 20-m-thick interval containing black shale interbedded with andesitic sills and intercalated with lensoidal calcarenites. The teeth have a characteristic labial peg with an accessory cusplet and a low gracile crown that is narrower labiolingually and more elongate laterally. The teeth are similar to some North American Late Triassic and Late Cretaceous species of the genus Lonchidion (e.g., L. humblei, L. griffisi, L. selachos), but are distinct in having a low primary cusp, up to seven pairs of lateral cusplets, a rounded-triangular-shaped labial peg with one accessory cusplet, and an absence of other crown ornaments. Color analyses of upper tooth crowns indicate an ichthyolith alteration index (IAI)/conodont alteration index (CAI) value of 6.0–6.5 (360–610°C). Considerable pitting and alteration of specimens indicates thermal alteration to 610°C and (or) chemical alteration.

Development and characterization of a cell line WAF from freshwater shark Wallago attu

A new epithelial cell line, WAF was developed from caudal fin of freshwater shark, Wallago attu. The cell line was optimally maintained at 28°C in Leibovitz-15 (L-15) medium supplemented with 20% fetal bovine serum. The cell line was characterized by various cytogenetic and molecular markers. The cytogenetic analysis revealed a diploid count of 86 chromosomes at different passages. The origin of the cell lines was confirmed by the amplification of 547 and 654bp sequences of 16S rRNA and cytochrome oxidase subunit I genes of mitochondrial DNA, respectively. WAF cells were characterized for their growth characteristics at different temperature and serum concentration. Epithelial morphology of the cell line was confirmed using immunocytochemistry. Further cell plating efficiency, transfection efficiency and viability of cryopreserved WAF cells was also determined. Cytotoxicity and genotoxicity assessment of cadmium salts on WAF cells by MTT, NR and comet assay illustrated the utility of this cell line as an in vitro model for aquatic toxicological studies. The cell line will be further useful for studying oxidative stress markers against aquatic pollutants.

Shark faunas from the Late Jurassic—Early Cretaceous of northeastern Thailand

A revision of the freshwater shark fauna from the Phu Kradung Formation in NE Thailand allows the recognition of a new species of Acrodus, which represents the youngest occurrence of the genus and confirms its displacement in freshwater environments after the Toarcian. The rest of the shark fauna includes teeth of Hybodus sp., aff. Hybodus sp., hybodontid dermal denticles, Jiaodontus sp., Lonchidion sp. A, Lonchidion sp. B, Heteroptychodus cf. H. kokutensis and dorsal fin spines. The presence of Jaiodontus and of unusual hybodontid dermal denticles suggests a Jurassic age for most of the Phu Kradung Formation, whereas the presence of Heteroptychodus suggests an Early Cretaceous age for the top of the Formation. However, the age of the Phu Kradung Formation is still uncertain, with contradictory signals coming from palynology, detrital zircon thermochronology and vertebrate palaeontology. In any case, it appears that this is the oldest occurrence of the genus Heteroptychodus, and suggests a Thai origin for this genus, which may have replaced Acrodus in the Thai freshwater palaeoecosystems. Together with Acrodus, the presence of Lonchidion sp. A suggests some European affinities for the shark fauna from the Phu Kradung Formation.

A new method to determine volume of bromalites: morphometrics of Lower Permian (Archer City Formation) heteropolar bromalites

Lower Permian vertebrates from both terrestrial and aquatic organisms have been collected from Archer County, Texas, for over a century. These include preserved shark cartilage and spiral bromalites presumed to have been produced by freshwater sharks of the genus Orthacanthus. Specimens were collected in the newly named Archer City Bonebed V occurring in the Archer City Formation. Physical characteristics (length, width, height, mass, eccentricity, volume, and density) were measured and recorded for 300 spiral bromalites and compared by linear regression analysis. The spiral bromalites had an average length of 31.74 mm; width 14.43 mm; height 10.51 mm, and mass 7.971 g. Eccentricity ranged from 0.9 to 0.06. All of these values follow a normal distribution. In addition to the collection of this statistical data, a new formula is proposed to help determine the volume of these elliptical fossils when volume determination by water displacement is not an option. The percent difference between the observed volumes obtained by water displacement and calculated volumes ranged from 0.04 to 56 %. Ninety-five percent of the statistical sample had a percentage difference of <30. This data, if compiled with data from the analysis of specimens from other localities, may ultimately reveal size groupings that could reflect the presence of previously unknown taxa that possessed a spiral valve and coexisted with the Orthacanthus sharks.

Functional dynamics observations of haptoral armature in Mizelleus indicus (Jain 1957) Pandey et al. 2003.

The negative effect of monogenea on piscine host may vary in the host species. Genus Mizelleus (Monogenea: Ancyrocephalidae) was reported for the first time from the freshwater shark, Wallago attu (Bl. and Schn.) at Lucknow by Jain (1957). Haptor or opisthohaptor of monogenea which is more or less discoid muscular structure situated posteriorly, is the chief adhesive organ. It is usually provided with anchors and marginal hooklets. Anchors, ventral transverse bar, together with the additional supporting dorsal bars (patches) are active elements of haptor while, marginal hooklets serve as secondary supportive participants, whereas, the dorsal transverse bar can be treated as an inactive element in the whole organ of attachment. Functional dynamics detail of haptoral armature is almost unattended. The anchors in case of M. indicus (Jain 1957) Pandey et al. (2003) are disposed one against the other and used to act like four lobed grapnel like a spreader. All components of haptoral armature contribute in one way or another in the process of functional process. Interestingly the worms do not follow the same pattern of sequences during their movements. Various elements and factors are involved in the process. The authors tried to pinpoint the changes in the activity of one major element i.e., dorsal anchor. The movement and change in position/orientation of various elements with reference to dorsal anchors were observed and summarized. Present paper is rare effort in unexplored aspect in monogenea biology.

Clarification of field characters for three freshwater sharks and a photographic atlas of 'Glyphis glyphis' and 'G. garricki' from the Adelaide River, Northern Territory, Australia

Eighty-two Glyphis glyphis, one G garricki and two Carcharhinus leucas were caught at six localities in the Adelaide River on 66 gill-netting trips from mid-May to mid-December during 2001, 2003-05 and 2009. Photographs are presented that differentiate these euryhaline sharks. The small second dorsal fin of C. leucas clearly separates it from Glyphis species. The waterline (i.e. junction of dark dorsal and pale ventral colouration) on G glyphis extends just under the eye whereas it extends well below the lower margin of the eye in G garricki. Photographs showing shark bite marks on other species are presented. Because of the presence of G glyphis under 610 mm TL with umbilical scars, it is postulated that Marrakai Creek is a nursery area and an important juvenile habitat of this species especially from September-December.

Characterization of Streptococcus iniae isolated from ornamental cyprinid fishes and development of challenge models

Streptococcus iniae was isolated from red-tail black shark(RTB shark) Epalzeorhynchos bicolor, and rainbow shark, E. erythrurus (fam: Cyprinidae), obtained from a local freshwater ornamental fish farm in Hillsborough county (FL). Darkening of the skin and lethargy were the first signs observed in infected sharks. Hemorrhages were observed on the ventral side of the body, on the head, and at the base of the pelvic and pectoral fins. Exophthalmia was observed in a low percentage of fish (∼ 10%). Moribund fish demonstrated the characteristic spinning, swimming pattern observed during streptococcal infections. Histological analysis revealed leukocyte infiltration in the intestinal area, spleen, posterior kidney, and brain. Necrosis and tissue degeneration were observed in the same organs in addition to degeneration of the renal tubules. Gram positive cocci were isolated from the cultures of brain and kidney tissues. Bacterial identification was obtained with the BIOLOG MicroLog3 version 4.00 System (Biolog, Inc., Hayward, California) and with standard microbiological tests. S. iniae-free RTB and rainbow sharks were used for developing a challenge model with the isolated bacteria strain. The experiments were conducted in two separate recirculating systems each with 25 tanks, 38 L volume per tank. In all experiments, the water in the system was maintained at 25 ± 1 °C. For each treatment, there were 3 replicate tanks, each stocked with 25 fish. Tanks were randomly assigned to treatment or control groups. Sharks were challenged by intracoelomic injection of S. iniae, and mortality was recorded for 14 days. Moribund fish showed classical signs of streptococcosis and S. iniae was isolated from moribund and dead fish. Differences in susceptibility to S. iniae were observed between the two species. An injection of 1.5 × 10 4 colony forming units (CFUs)/fish caused mortality close to 70% in RTB shark, and a higher mortality rate in rainbow shark. Mortalities ceased in 11–12 days after bacterial challenge in RTB shark, and in 3–4 days in rainbow shark. In this report, the pathology of S. iniae infections in two ornamental freshwater sharks and the development of a challenge model are described.

Un nouveau gisement à microrestes de vertébrés continentaux et littoraux dans le Cénomanien inférieur de Fouras (Charente-Maritime, Sud-Ouest de la France)

A new continental and coastal vertebrate locality in the Early Cenomanian of Fouras (Charente-Maritime, southwestern France). The Cretaceous period represents crucial times in vertebrate evolution, notably with the emergence of modern mammal groups. In Europe, continental formations are restricted to the basal and Latest Cretaceous (Wealdian and Campano-Maastrichtian). Concerning the middle part of the Cretaceous, continental vertebrate faunas are poorly known, generally through some particular assemblages deposited in paralic environments and mostly composed of microremains. Such a deposit, recently found in the Early Cenomanian of Fouras (Fouras-Vauban locality, Charente-Maritime, southwestern France), has yielded a rich association, improving our knowledge. Beside abundant coastal fish remains, tetrapods are represented by chelonians, crocodilians, ophidians, plesiosaurs, pterosaurs, and dinosaurs. The occurrence at Fouras-Vauban of certain typical Gondwanan forms (the freshwater shark Tribodus and a zyphodont crocodilian close to Hamadasuchus) allows us to discuss about the palaeobiogeographical affinities of faunas living in the European archipelago during the Mid-Cretaceous and the trans-Tethyan ways of communication between Western Europe and North Africa. To cite this article: R. Vullo et al., C.R.Palevol 4 (2005) .

The conchostracan subgenus Orthestheria (Migransia) from the Tacuarembó Formation (Late Jurassic–?Early Cretaceous, Uruguay) with notes on its geological age

Conchostracans from the Tacuarembó Formation s.s. of Uruguay are reassigned to the subgenus Orthestheria (Migransia) Chen and Shen. They show more similarities to genera of Late Jurassic age in the Congo Basin and China than to those of Early Cretaceous age. On the basis of the character of the conchostracans, we suggest that the Tacuarembó Formation is unlikely to be older than Late Jurassic. It is probably Kimmeridgian, but an Early Cretaceous age cannot be excluded. This finding is consistent with isotopic dating of the overlying basalts, as well as the age range of recently described fossil freshwater sharks.

Direct ion microprobe U–Pb dating of fossil tooth of a Permian shark

We report here direct ion microprobe dating of fossil tooth (dentine) of a Permian fresh-water shark, Orthacanthus senckenbergianus using the SHRIMP instrument recently installed at Hiroshima University. Fifteen spots on the small sample (approximately 2 mm×1 mm) indicate a 238U/ 206Pb isochron age of 266±18 Ma and a Tera–Wasserburg concordia intercept age of 266±24 Ma in a three-dimensional 238U/ 206Pb– 207Pb/ 206Pb– 204Pb/ 206Pb diagram. These Permian ages are consistent with a 235U/ 207Pb age of 453±170 Ma and a 232Th– 208Pb age of 235±310 Ma, suggesting indistinguishable depositional and early diagenetic ages of the fossil in its sedimentary sequences. The success of the method depends on the chemical fractionation of uranium from lead in a specimen a few hundred microns in size and the consequent variations in lead isotopic compositions due to radioactive decay.

Freshwater shark attacks at Basrah, Iraq

Abstract Eleven, separate shark attacks on humans in freshwater are reported from Basrah, Iraq. Two attacks were fatal. The shark species involved is probably Carcharhinus leucas.

Freshwater shark teeth as paleoenvironmental indicators in the Upper Pennsylvanian Morien Group of the Sydney Basin, Nova Scotia

Algal limestones in the coal-bearing upper part of the Pennsylvanian Morien Group in the Sydney Basin, Nova Scotia, contain abundant fish fragments. A wide variety is present, including remains of bony fish, lungfish, and sharks. Of these, the most significant environmentally are the lungfish and the teeth and skeletal fragments from freshwater xenacanthid sharks. Their presence confirms the earlier diagnosis of nonmarine conditions derived from the nature of the sedimentary succession and the other biota present. Lithologic and faunal associations suggest that the xenacanthid sharks lived mainly in shallow, alga-bearing lakes on alluvial plains, whereas the bony fish were also tolerant of more restricted swampy environments marginal to the lakes.

Ultrastructural study and comparative analysis of fluoride content of enameloid in sea-water and fresh-water sharks

The ultrastructural and chemical similarity of enameloid of Carcharhinus leucas (living in fresh water) and sea-water sharks ( Prionace glauca, Dalatias lichas) was confirmed by scanning electron microscopy, high resolution electron microscopy, X-ray diffraction analysis, electron microprobe point analysis and direct potentiometric analysis in a iono-analyser with specific electrode. The mean thickness and width measurements of enameloid crystals performed in high resolution TEM were respectively, 47.1 nm (standard deviation 6.8) and 52.3 nm (standard deviation 7.3). The fluoride content of selachian enameloid was nearly as high as that of fluorapatite. However, the fluoride concentration was higher in non-erupted than in erupted teeth of fresh-water sharks, indicating that fluoride content in enameloid is programmed by the ameloblasts and not due to diffusion from the environment.

Fish protein concentrate from freshwater shark (Wallago attu)

The possibility of utilisation of a low priced catfish known as freshwater shark (Wallago attu) for the production of cheap and widely acceptable form of protein concentrate (FPC) has been studied. The fish could be converted into a product having good dispersible and better functional qualities of protein by solvent-extraction and other process techniques. Conventional processing was found to be improved by washing the fish in brine and initial steaming operation. Both steaming and use of brine during blending gave good appearance of the product. Slight hydrolysis with enzyme pepsin produced better foaming and required dispersion. The treatment with acetic acid resulted in a good swelling effect of the FPC.

The Status of the Freshwater Shark of Lake Nicaragua

Nineteen sharks collected from freshwater at several points on Lake Nicaragua and the Rio San Juan were all of the same species and indis­ tinguishable from marine Carcharhinus leucas of the Atlantic. Minor differences previously thought to separate C. leucas from the lake shark proved to be invalid. Females had slightly longer gill slits, somewhat greater breadth of pelvic fin, and a longer abdominal region than males. Clasper length indicated that the onset of sexual maturity in males occurs when they are between 1,600 and 1,700 mm in total length. The classical theory or origin of the sharks from Pacific ancestry no longer appears tenable. An Atlantic origin is indicated by (a) strong evidence that the taxonomic affinities not only of the shark, but also of the sawfish and tarpon, are more pronouncedly with Atlantic relatives than with those of the Pacific, (b) recent evidence that Lake Nicaragua may never have been a part of the Pacific but opened originally to the Atlantic, (c) the fact that Lake Nicaragua drains into the Caribbean Sea by a large, broad river, and (d) all three of the large, otherwise marine types of fish occurring in the lake are species that habitually congregate in brackish water and frequently move up rivers. Evidence that the sharks are not landlocked includes the following facts: (a) they are abundant the full length of the river, (b) barges drawing from one to three feet of water regularly negotiate the river (including all of the rapids) in both directions, (c) sharks were observed both below and above the three major rapids as well as actually in the rapids, most of them headed upstream.

Calcium and other ions in blood and skelton of Nicaraguan fresh-water shark

Calcium and other ions in blood and skelton of Nicaraguan fresh-water shark

Rectal Glands of Marine and Fresh-Water Sharks: Comparative Histology

The rectal glands of elasmobranchs perform the function of salt-excreting organs. These glands are smaller and show regressive changes in specimens of the bull shark, Carcharhinus leucas found in fresh-water environment, compared with specimens of this and other species from a marine habitat.

Calcium and Other Ions in Blood and Skeleton of Nicaraguan Fresh-Water Shark

The bull shark, Carcharhinus leucas, employing archaic but effective means of regulating the physical-chemical composition of its body fluids, thrives in tropical fresh-water rivers and lakes. The ionic strength of the serum and the concentrations of total solutes, calcium, urea, and other ions are below the levels found in marine elasmobranchs but higher than the levels in teleosts. The patterns of the calcium deposits of the vertebrae are identical in marine and fresh-water subspecies.

Calcium and Other Ions in Blood and Skeleton of Nicaraguan Fresh-Water Shark

The bull shark, Carcharhinus leucas, employing archaic but effective means of regulating the physical-chemical composition of its body fluids, thrives in tropical fresh-water rivers and lakes. The ionic strength of the serum and the concentrations of total solutes, calcium, urea, and other ions are below the levels found in marine elasmobranchs but higher than the levels in teleosts. The patterns of the calcium deposits of the vertebrae are identical in marine and fresh-water subspecies.

Latent Learning in Earthworms

Latent Learning in Earthworms