Stingray Dasyatis Research Articles

Using opportunistic data to study the distribution and abundance of a warm water elasmobranch at the northern edge of its range

Abstract Detecting changes in the distribution and abundance of marine species that are cryptic or occurring in very low abundances is difficult, but essential for assessing their status and informing management. One way of quantifying these changes is through the collation of opportunistic records. We reconstruct the population trajectory and distribution of the common stingray Dasyatis pastinaca around Great Britain, using opportunistic records, mostly obtained by recreational anglers. We tested if D. pastinaca declined in abundance and body size in response to fishing and if their distribution has shifted northwards in response to warming seas. We obtained 518 records covering the period 1838–2020. After correcting for observation effort, D. pastinaca catches reported by anglers showed no long-term trend over 50 years, but decreased from 1970 to 1995 and an increase in abundance since 1995. While records of species occurrence were found around much of Great Britain, nearly all were from south of 54° latitude, and records have contracted southwards since 2000. No trend in maximum size through time was detected. In conclusion, we did not find support for the hypothesized declines in abundance and body size or a northward shift in distribution of D. pastinaca and instead found a southward contraction.

Preliminary evidence of a potential reproductive aggregation area of the common stingray Dasyatis pastinaca (Linnaeus, 1758) (Chondrichthyes – Dasyatidae) in the Central Mediterranean Sea

Shallow and coastal aggregations of batoids are poorly documented in the Mediterranean Sea, despite being likely threatened by multiple anthropogenic pressures. We report the first observations of a potential summer reproductive aggregation of the common stingray (Dasyatis pastinaca). The recurrent presence in previous years of several pregnant females, a mature male and a female with fresh bite wounds was recorded in shallow waters by recreational scuba divers and scientists in Scilla Bay (Strait of Messina, Italy), a location with unique oceanographic features in the Central Mediterranean Sea. These observations suggest that the area could be used as a parturition and mating site in early summer, and this is significant for the conservation of this Vulnerable species.

Genetic characterisation of Echinocephalus spp. (Nematoda: Gnathostomatidae) from marine hosts in Australia.

We genetically characterised larval and adult specimens of species of Echinocephalus Molin, 1858 (Gnathostomatidae) collected from various hosts found within Australian waters. Adult specimens of Echinocephalus were collected from a dasyatid stingray [Pastinachus ater (Macleay); n = 2] from Moreton Bay, Queensland and larvae from a hydrophiine sea snake [Hydrophis peronii (Duméril); n = 3] from Cape York Peninsula, Queensland, from an octopus (Octopus djinda Amor & Hart; n = 3) from Fremantle, Western Australia and from a lucinid bivalve [Codakia paytenorum (Iredale); n = 5] from Heron Island, Queensland Australia. All nematode samples were identified morphologically and genetically characterised using the small subunit nuclear ribosomal DNA (SSU). Some morphological differences were identified between previous studies of Echinocephalus spp. and those observed herein but the significance of these differences remains unresolved. Molecular phylogenetic analyses revealed that larval Echinocephalus sp. from H. peronii and C. paytenorum in Australia were very similar (with strong nodal support) to larval Echinocephalus sp. infecting two fish species from Egypt, Saurida undosquamis (Richardson) (Synodontidae) and Pagrus pagrus (Linnaeus) (Sparidae). The SSU sequences of larval Echinocephalus sp. from O. djinda and adults from P. ater formed a well-supported clade with that of adult E. overstreeti Deardorff and Ko, 1983 from the Port Jackson shark, Heterodontus portusjacksoni (Meyer), as well as that of the larval Echinocephalus sp., from the common carp (Cyprinus carpio Linnaeus) from Egypt. This study extends the intermediate host range of Echinocephalus larvae by including a sea snake for the first time. Findings of this study highlight the importance of genetic characterisation of larval and adult specimens of Echinocephalus spp. to resolve the current difficulties in the taxonomy of this genus.

Three New Species of Rhinebothrium (Cestoda: Rhinebothriidea) from the Leopard Whipray, Himantura Leoparda, in Australia.

Examination of 4 specimens of the leopard whipray Himantura leoparda, a dasyatid stingray from northern Australia, led to the discovery of 3 new species of Rhinebothrium. Rhinebothrium leopardensis n. sp., Rhinebothrium nandoi n. sp., and Rhinebothrium ruhnkei n. sp. are described, increasing the diversity of the genus to 51 species globally. All 3 new species differ from their congeners in terms of testis number, proglottid number, loculus number, and size. With respect to one another, R. leopardensis n. sp. has bothridia that are weakly constricted at their centers and has a greater number of proglottids than the other 2 species (93-108 vs. 11-15, and 48-78, respectively). Rhinebothrium nandoi n. sp. is the smallest of the 3 species found in H. leoparda (3.6-5 vs. 10-15 mm and 10.1-15.8 mm in total length [TL], respectively) and bears bothridia that are constricted at their centers. Rhinebothrium ruhnkei n. sp. bears bothridia that are conspicuously constricted at their centers and has more testes than R. leopardensis and fewer than R. nandoi (7-10 vs. fewer than 7 and 21-33, respectively). Before this study, 56% (27 of 48) of Rhinebothrium species had been described from the freshwater river systems of South America and the marine waters surrounding South and North America. In contrast, despite the remarkably diverse nature of its batoid fauna, only 19 species were known from the Indo-Pacific region. Our work increases this number to 22, emphasizing the highly underestimated nature of Rhinebothrium diversity in this region of the globe. The discovery of these 3 new species was not unexpected, given the relatively poor status of our current knowledge of the cestode faunas of dasyatid stingrays in the Indo-Pacific region, and given the fact that it is common for a single batoid species to host 2 or more species of Rhinebothrium. Our results suggest that additional work on the cestode faunas of the batoids, especially dasyatids, from the Indo-Pacific region is likely to be highly productive in terms of contributing to the knowledge of Rhinebothrium diversity.

The First Report and Description of a New Species of Rhinebothrium from a Dasyatid Stingray from the Brazilian Northeastern Coast with a Review of the Distribution of the Genus throughout Endemic Marine Ecoregions.

Here we describe a new species of RhinebothriumLinton, 1890, from Hypanus guttatus (Bloch and Schneider). Rhinebothrium ramosi n. sp. can be differentiated from all 51 valid species of the genus by having 4-5 testes and uterus that extends throughout the entire length of the proglottid. Only 8 of the above species closely resemble R. ramosi in total length (Rhinebothrium bunburyense, Rhinebothrium chollaense, Rhinebothrium corbatai, Rhinebothrium dasyatidis, Rhinebothrium kruppi, Rhinebothrium lintoni, Rhinebothrium margaritense, and Rhinebothrium reydai). Despite the resemblance, R. bunburyense, R. corbatai, R. dasyatidis, R. lintoni, and R. margaritense can be distinguished from the new species by possessing a larger number of proglottids. The remaining 3 species (R. chollaense, R. kruppi, and R. reydai) overlap in total length and number of proglottids with R. ramosi. However, they can be distinguished from the new species by possessing a single posterior-most bothridial loculus instead of arranged as a pair, as found in the new species. This is the first report of the genus from the coastal waters of Brazil and brings to 52 the number of valid species for this genus. Additionally, we use the patterns of infection and distribution for species of Rhinebothrium to make predictions of expected diversity within the genus, especially for unsurveyed hosts in endemic marine ecoregions of the world.

Morphological variation in the hyperapolytic lecanicephalidean species Anteropora japonica (Yamaguti, 1934) (Eucestoda)

In November of 2013, a specimen of Japanese sleeper ray, Narke japonica (Temminck et Schlegel), caught off Nanfang-ao, Taiwan was found to be parasitised by the cestode Anteropora japonica (Yamaguti, 1934). Specimens comprised whole worms and free proglottids, both of varying degrees of maturity. This material allowed for the opportunity to examine in detail the developmental progression of this hyperapolytic lecanicephalidean species with regard to overall size, scolex dimensions, and microthrix pattern. Complete immature worms ranged in size from 2.4 mm to 14 mm. The smallest scoleces were half as wide as larger scoleces and exhibited a much smaller ratio of apical organ width to bothridial width. Proglottids more than quadrupled in length during maturation from terminal attached immature to detached proglottids. In addition, a change in microthrix pattern was observed on the anterior region of the proglottids from immature to gravid proglottids; the anterior region of attached immature proglottids is covered with gladiate to coniform spinitriches with capilliform filitriches only rarely visible, whereas this region in detached proglottids is covered with gladiate to coniform spinitriches and conspicuous capilliform filitriches. This is the first report of A. japonica from outside Japan expanding its distribution south to Taiwan. In addition, a preliminary phylogenetic analysis of the genus is presented that suggests congeners from the same host species are not each other's closest relatives, nor is there an apparent phylogenetic signal for apical organ type or reproductive strategy (apolysis). However, reproductive strategy does seem to be correlated with host group such that euapolytic species parasitise dasyatid stingrays while hyperapolytic species parasitise either torpediniform rays or orectolobiform sharks.

Effect of stingray (Hemitrygon akajei) foraging on a ghost shrimp population (Nihonotrypaea harmandi) on an intertidal sandflat, western Kyushu, Japan

Callianassid shrimp residing in deep burrows have large bioturbating effects on marine soft-bottom communities. A few predators that excavate deep pits could have substantial effects on shrimp populations, as well as knock-on effects. Processes and consequences of such effects on shrimp populations are poorly understood. On a 300-m-wide intertidal sandflat area between tide marks in western Kyushu between 1989 and 1994, shrimp population densities were stable, reaching >1300individualsm–2. Dasyatid stingray feeding pits reaching depths up to 20cm occurred abruptly in large numbers in 1994, after which shrimp densities decreased yearly to hundreds of individuals per square metre in 2001. The densities of ray feeding pits formed per day were monitored every or every other spring tide between 2000 and 2001. Schools of rays were enclosed during submerged times and their body sizes recorded alive to determine size-frequency distribution. The body-size frequency distributions of shrimp were compared among the gut contents of several rays, ray feeding pits and intact sandflat. Reductions in the shrimp density per ray feeding bout compared with the density on the intact sandflat were recorded. A model of daily predation at different seasonal rates was used to simulate the yearly change in shrimp density. The result was consistent with the actual change.

Development of a system for measuring calcitonin in the stingray Dasyatis akajei (a cartilaginous fish): the possible involvement of stingray calcitonin in gonadal development

To elucidate the physiological role of calcitonin (CT) in stingrays (cartilaginous fish), an enzyme-linked immunosorbent assay (ELISA) system using a specific antibody against stingray CT has been developed. Synthetic stingray CT was subcutaneously injected into mice four times—once every 2 weeks—together with an adjuvant. We purified the IgG antibody fraction using the protein A affinity chromatography from collected antiserum. Evaluating the antibody titer, we found the antibody’s optimum dilution ratio to be 600 times. Competitive ELISA has been developed using the antibody diluted 600 times. Our antibody did not cross-react with teleost CTs and muscle extraction, but cross-reacted with stingray plasma and the extract of the ultimobranchial gland, the secretary organ of stingray CT. Using this ELISA, we measured the plasma CT level in stingrays and examined its correlation with several mineral concentrations. Plasma CT did not show significant correlation to calcium, magnesium, inorganic phosphorus, sodium, chlorine, or urea, although there was a correlation among the factors involved in osmoregulation, such as sodium, chlorine, and urea. On the other hand, plasma CT was significantly correlated to body weight and length. Furthermore, there was a significant correlation between plasma CT and gonad weight. Since plasma CT was correlated with the weight of liver, which is involved in the synthesis of egg yolk protein, we examined the influence of 17β-estradiol (E2) on CT secretion. After E2 injection, the plasma CT level increased significantly. This is the first study to demonstrate that E2 induced plasma CT secretion in cartilaginous fish.

An innovative fishing gear to enhance the release of non-target species in coastal shark-control programs: The SMART (shark management alert in real-time) drumline

In response to a spate of shark attacks in Reunion Island in the southwest Indian Ocean since 2011, local authorities developed an experimental shark-control program based on those conducted for decades in Australia and South Africa. In order to greatly reduce, if not eliminate, the impact of such a shark fishing program on bycatch and undersized target shark species, the use of conventional “drumlines” was improved by the addition of an innovative “Catch-A-Live”® system, making the drumlines ‘SMART’ (Shark Management Alert in Real Time). This is a real-time strike alert system based on an adapted triggering mechanism, which links the fishing line to a GPS buoy connected to the Iridium satellite. This system alerts fishers on duty via a computer-based communication system within just a few minutes, enabling immediate intervention. Off Reunion Island, up to 20 SMART drumlines (SDLs) were deployed along the west and southwest coast in coastal waters to target bull (Carcharhinus leucas) and tiger sharks (Galeocerdo cuvier) in trials conducted between 2014 and 2017. During 58,770 h of fishing there were 269 catches of more than 14 species, of which 86.9% were retrieved alive. There were marked differences in survival among species. While the most fragile species were the giant trevally (Caranx ignobilis), scalloped hammerhead sharks (Sphyrna lewini) and small carcharhinid species, most of the other bycatch species (stingrays Dasyatis sp., giant guitarfish Rhyncobathus djiddensis, and tawny nurse sharks Nebrius ferrugineus) were generally found alive and in a condition suitable for tag and release. Of the target species, 94.8% of all individuals were found alive. These survival rates are far higher than those of other programs using conventional drumlines in KwaZulu-Natal (South Africa) and Queensland (Australia). There were strong diurnal and lunar catch patterns. This information is invaluable in planning fishing operations to maximise the catch of the target species, while reducing the chances of killing the bycatch. These results highlight the potential for use of SDLs in research programs aimed at tagging large sharks capable of tripping the trigger, especially in situations where catch rates are so low that it is impractical for the fishing vessel to remain at sea for the duration of each fishing operation.

Reproduction and embryonic development of the red stingray Hemitrygon akajei from Ariake Bay, Japan

The reproductive system of the red stingray Hemitrygon akajei was described from 1,418 specimens, 682 males and 736 females, sampled year-round (2003–2014) from Ariake Bay to provide reproductive life history information for conservation and management of the species. Females reach sexual maturity at a larger size than males with the size at 50% sexual maturity 522.2 mm disc width (DW) and 321.5 mm DW, respectively. Male stingrays had semen in the seminal vesicles year-round. Dental sexual dimorphism was aseasonal. The mating period is protracted, spanning 7 consecutive months October–April but ovulation occurred during May. This suggests female sperm storage, which has not been described for dasyatid stingrays. Females have a single functional ovary and uterus (left) and reproduce via aplacental viviparity with lipid histotrophy. Gestation required 3 months with parturition during late July and early August. Uterine eggs without macroscopic embryos were observed during the first half of gestation suggesting a short period of arrested development or diapause. Developmental cohorts based on morphological features were described for embryos and can be used to characterize embryo growth and development for other stingray species. Observations of foetal mortality (1.25%) and morphologically abnormal embryos (0.72%) were uncommon. Pregnancy rate was 90% and reproduction was annual and synchronous. Hemitrygon akajei fecundity ranged from 7 to 25 and increased with female size. Although H. akajei is a medium-sized dasyatid ray, it has the highest fecundity reported for any batoid species. Elasmobranchs life histories usually are associated with a low degree of productivity that results in rapid population decline with increased fishing pressure. Producing high numbers of small young is a successful reproductive strategy for H. akajei that may be partly responsible for their resilience to fishing pressure and continued abundance in Ariake Bay. This study is the first to describe reproduction of H. akajei, an economically important top predator inhabiting coastal ecosystems throughout Asia.

Ultrastructure of Intestinal Epithelium in Cartilaginous Fish

By means of electronic microscopy, the structural distinctions of epithelial cells are revealed in three species of cartilaginous fish differing in their foraging: spiny dogfish Squalus acanthias (a typical fish predator), common stingray Dasyatis pastinaca, and thornback ray Raja clavata (benthos eaters-facultative fish predators). In the spiny dogfish, the length of microvillu in the brush border of enterocytes in the medial region of the spiral intestine is smaller than in Dasyatis pastinaca and Raja clavata (0.66 ± 0.05 vs. 1.16 ± 0.07 and 1.04 ± 0.10 μm) and their diameter, on the contrary, is greater (0.10 vs. 0.08 and 0.07 μm). In Dasyatis pastinaca, there is a well-developed glycocalix and the distal decrease of microvilli length. The role of the brush border enetocytes in the increase of digestive and transport surface of the intestine, as well as the role of particular organelles in digestions and transport of nutrients in the investigated fish, is discussed.

A molecular approach towards taxonomic identification of elasmobranch species from Maltese fisheries landings

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. Each species was analysed using these two mtDNA loci where COI (610bp) and ND2 (990bp) efficiently distinguished between the various species studied, leading to the identification of 101 haplotypes, with the intraspecific p-distance ranging between 0 and 0.75% (mean 0.10%, SD ±0.13%). This study enhances the molecular data available on elasmobranchs by providing new ND2 sequences for various species, while providing both COI and ND2 data for poorly studied Mediterranean species including: the large pelagic sharks Alopias vulpinus, A. superciliosus, Carcharhinus altimus, C. plumbeus, Carcharadon carcharias, Isurus oxyrinchus, Prionace glauca and Odontaspis ferox; the smaller demersal sharks Somniosus rostratus, Squatina aculeata, S. oculata and Squalus sp.; and the endemic stingray Dasyatis tortonesei. It also confirmed the landings of species whose identification relies strongly on molecular tools, namely Squalus sp. and D. tortonesei, which are both first confirmed records amongst Maltese fisheries landings. Morphologically, the latter two species, can be easily misidentified with S. blainville and D. pastinaca respectively. Additionally, this study evaluated the genetic differences between different polychromatic forms of Raja clavata, R. radula and Dipturus oxyrinchus. Based on the currently analysed specimens, no significant genetic differences were found between the various forms and thus no further speciation within the species was identified.

Ingestion of Stingrays (Dasyatis spp.) by a Common Bottlenose Dolphin (Tursiops truncatus)

Ingestion of Stingrays (Dasyatis spp.) by a Common Bottlenose Dolphin (Tursiops truncatus)

NUEVOS REGISTROS DE PECES DE ESQUELETO CARTILAGINOSO PARA EL CARIBE COLOMBIANO Y UNO COMO AMPLIACIÓN DE SU DISTRIBUCIÓN GEOGRÁFICA EN EL CARIBE COLOMBIANO PARA BOCAS DE CENIZA, DEPARTAMENTO DE ATLÁNTICO, COLOMBIA

Three new records of cartilaginous fishes are added and the area of distribution of one species is expanded for the Colombian Caribbean. These are: the bramble shark Echinorhinus brucus (Bonaterre), the sand tiger shark Odontaspis ferox (Risso), the roughtail stingray Dasyatis centroura (Mitchill) and the bluntnose sixgill shark Hexanchus griseus (Bonaterre). The animals were captured by artisanal fishermen from Las Flores, Barranquilla, using long-lines, at Bocas de Ceniza, next to the mouth of the Magdalena river (Atlántico Department), Colombian Caribbean

Using acoustic telemetry to assess patterns in the seasonal residency of the Atlantic stingray Dasyatis sabina

The Atlantic stingray Dasyatis sabina is found along the Atlantic and Gulf coasts of the United States. It consumes commercially important shrimp and crabs, and its diet overlaps with recreationally valuable red drum Sciaenops ocellatus and pompano Trachinotus spp. Despite the potential economic impact of this species, it is unclear whether the Atlantic stingray is present year-round or only seasonally in coastal habitats. The objective of this study was to assess the seasonal residency patterns of Atlantic stingrays in two creek systems in the Savannah River estuary. Forty stingrays were tracked using acoustic telemetry, and a seasonal residence index was calculated for each individual. Atlantic stingrays were present year-round in the Savannah River estuary, as 15 % (n = 6) of the tagged rays remained in the study areas throughout the year. This is the northernmost region where this species has been documented to be present all year. Of the 85 % (n = 34) of the rays that migrated during winter, 38 % (n = 13) of those were detected within the estuary less than 20 km away. Had trawls or mark-recapture been used instead, the few animals remaining in the creek systems and/or those that migrated may not have been collected. Acoustic telemetry is a more accurate means of studying the residency of fishes than periodic sampling that requires capture, and researchers should consider incorporating this technology in future studies about fish-environment interactions. Underestimating the presence of a species could result in miscalculation of its economic and ecological impact and, by extension, result in the implementation of ineffective or even detrimental management strategies.

Data for amino acid alignment of Japanese stingray melanocortin receptors with other gnathostome melanocortin receptor sequences, and the ligand selectivity of Japanese stingray melanocortin receptors

This article contains structure and pharmacological characteristics of melanocortin receptors (MCRs) related to research published in “Characterization of melanocortin receptors from stingray Dasyatis akajei, a cartilaginous fish” (Takahashi et al., 2016) [1]. The amino acid sequences of the stingray, D. akajei, MC1R, MC2R, MC3R, MC4R, and MC5R were aligned with the corresponding melanocortin receptor sequences from the elephant shark, Callorhinchus milii, the dogfish, Squalus acanthias, the goldfish, Carassius auratus, and the mouse, Mus musculus. These alignments provide the basis for phylogenetic analysis of these gnathostome melanocortin receptor sequences. In addition, the Japanese stingray melanocortin receptors were separately expressed in Chinese Hamster Ovary cells, and stimulated with stingray ACTH, α-MSH, β-MSH, γ-MSH, δ-MSH, and β-endorphin. The dose response curves reveal the order of ligand selectivity for each stingray MCR.

Characterisation of eleven new polymorphic microsatellite markers for the coastal stingray Dasyatis brevicaudata (Dasyatidae Hutton 1875), and cross-amplification in seven dasyatid species

Twelve microsatellite loci were developed for the short-tailed stingray Dasyatis brevicaudata using a next-generation sequencing approach, and their utility for population genetics studies was assessed. Eleven out of twelve loci were polymorphic (4–15 alleles) and amplified reliably, with observed heterozygosities between 0.32 and 0.86 (mean = 0.56). Successful cross-species amplification of many of these markers was achieved across seven other dasyatid species currently listed as “Data Deficient” by the IUCN, suggesting these microsatellites will be a useful resource for the investigation of ecological and conservation genetics in a range of species of conservation concern.

Monocotyle luquei n. sp. (Monogenea: Monocotylidae), from the gills of diamond stingray Dasyatis dipterura (Jordan and Gilbert, 1880) (Myliobatiformes: Dasyatidae), in the South Pacific.

Monocotyle luquei n. sp. (Monogenea: Monocotylidae) was described from gills of diamond stingray Dasyatis dipterura (Jordan and Gilbert, 1880) (Dasyatidae) off Peru. The new species can be differentiated from the other species of the genus by the combination of the following characteristics: (1) accessory sclerites on the dorsal posterior surface of the body absent, (2) only one testis is present, (3) 1-2 loops in the copulatory organ, (4) the male copulatory organ with a sclerotized accessory piece, (5) shape of five sclerites in marginal papillae, (6) size of anchor and (7) posterolateral septa bifurcated. This is the first record of species of Monocotyle Taschenberg, 1878 from the southern Pacific.

Antiproliferative activity of marine stingray Dasyatis sephen venom on human cervical carcinoma cell line.

BackgroundVenoms comprise mixtures of numerous bioactive compounds that have a wide range of pharmacologic actions. Toxins from venomous animals have attracted the attention of researchers because of their affinity for primary sites responsible for lethality and their efficacy at extremely low concentrations. The venoms of marine stingrays have not been extensively studied and limited data is available on them. The present study aims to evaluate the antiproliferative and biochemical properties of the venom obtained from a species of marine stingray (Dasyatis sephen) on human cervical cancer cell line HeLa.MethodsThe antiproliferative effect of D. sephen venom was determined by MTT assay, and the oxidative stress was determined by lipid peroxidation method along with assessment of changes in the enzymatic and non-enzymatic antioxidant status. We observed intracellular reactive oxygen species (ROS) levels by DCFH-DA method, mitochondrial membrane potential alterations by rhodamine 123 staining and apoptotic morphological changes by acridine orange/ethidium bromide dual staining method.ResultsD. sephen venom enhances lipid peroxidative markers such as thiobarbituric acid reactive substance, conjugated diene, and lipid hydroperoxide in HeLa cell lines. Stingray venom enhances the ROS levels, which is evidenced by the increased 2–7-diacetyl dichlorofluorescein fluorescence. Further, D. sephen venom treatment altered the mitochondrial membrane potential in HeLa cells. Additionally, we observed increased apoptotic morphological changes in D. sephen venom-treated groups.ConclusionsDasyatis sephen venom exhibits potent antiproliferative effect on HeLa cell line and upon further purification it could be a promising antiproliferative agent.Electronic supplementary materialThe online version of this article (doi:10.1186/s40409-015-0036-5) contains supplementary material, which is available to authorized users.

First record of total albinism in southern stingray Dasyatis americana

This paper describes the first record of total albinism in the southern stingray Dasyatis americana. The disc width of the albino sub adult female specimen was 640 mm and the total weight was 9,850 g. It was captured in the coast of Tabasco, southeastern Mexico.