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  • Survey of Monsoon phenomenon effect on heavy metals concentration (Cd, Cu, Ni, Pb and Zn) in the sediment of Gulf of Gwatr to Pozm

    Safahieh, A.R.; Pakzadtoochaei, S.; Ronagh, M.T.; Archangi, B.; Hamzeh, M.A. (2014)
    In this study, the molecular characteristics of Chiromantes boulengeri in 2014 from intertidal waters of Arvand River in the vicinity of Minoo island were investigated. So, in October 2014 specimens from intertidal of two area of Minoo island were collected and preserved in 70% ethanol, carried out to the khoramshahr University of Marine Science and Technology laboratory and examined. To fulfill the purpose, To extract the DNA, phenol- chloroform method were used and mitochondrial gene 16S rRNA was sequenced and compare with other species from GenBank NCBI. The morphological and phylogeny sequencing results showed that all specimens belong to Chiromantes boulengeri in the study area. By polymorphism analysis, there are mutation within C. boulengeri from two area of Arvand River and it seems that this species for its survival has adapted with different ecological conditions in the study area.
  • Macrobenthos assemblage in the shallow- water coast’s of the south Qeshm Island, with acoustic remote sensing technique

    Haghi, M.; Savari, A.; Kochanian, P.; Nabavi, S.M.B.; Nami, M.H.; Zakeri, M.; Bodaghi, M. (2014)
    In this study the macrobenthose assemblage and their relationship with sediment texture was investigate by acoustic remote sensing. Macrobenthse in marine sediment plays an important role in ecosystem and any fluctuation in their communities will directly affect the abundance of fishery resources in the sea. Acoustic remote sensing techniques investigate the vast seabed in rather small time interval. This survey site covers approximately 233km2. Geophysics data was derived by single beam echo sounder and differential global positioning system. The sediment texture and macrobenthose identification was done with grab sampling. The most study area is shallow and covered with mud. Dominant benthic animals were Cirratulidae, Amphionomidae and Paraonidae from Polychaetes. The sediment types have no important and significant effect on distribution and richness. Thus, in all stations with monotone sediment texture, there is similar species composition. Because of monotone geological characteristic in seafloor, macrobenthose assemblage patterns are not affected by sediment texture and grain size.
  • Synthesis and Characterization of Aluminum Oxide Nanoparticles Using Macroalgae Sargassum Ilicifolium

    Koopi, H.; Buazar, F. (2018)
    Nanoparticle biosynthesis is considered an important part of nanotechnology which is economically viable; it is an environmentally-friendly procedure with great advantages compared to physical and chemical ones. In the present study, a green approach is presented for the first time for producing alpha aluminum oxide nanoparticles using Sargassum ilicifolium algae in which its methanolic algae extract was employed as a reducing agent and stabilizer layer. Under optimal conditions of 25ºC and pH=4, 10% of algae extract concentration and 0.05M Al2(SO4)3 salt, aluminum cations were reduced completely to nanoscale phase within 24 hours. XRD technique confirms the formation of alpha aluminum oxide size 35 nanometers in a hexagon shape. The results of TEM confirms the spherical almost shape of the produced nanoparticle, the results of SEM shows the average size 33.40 of the nanoparticle, and the results of EDX indicated the purity of the produced nanoparticle which is formed of only oxygen and aluminum atoms.
  • Investigation of effect weight of parameters affecting the hydrodynamic coefficients in design of surface-piercing propellers

    Donyavizadeh, N.; Shafaghat, R.; Dardel, M.; Mohammadzade Negharchi, S. (2018)
    High speed craft with the wide and various uses of entertainment, sporting, commercial and military, usually has a top speed of 30 knots. Due to the limitations of the design, use of propulsion system is a key issue, with regard to the desirable features surface-piercing propeller, their use in the propulsion system of the vessel, has been very useful. High efficiency, no restrictions to increase the diameter, resistance equipment supplied propeller removed, the proper functioning of cavitation, are examples of these features. To achieve the best efficiency and thrust requirements, requires accurate determination of the coefficient of hydrodynamic thrust and torque. Given the importance of determining the coefficients and their dependence on various physical parameters and geometric, it is necessary to understand the effect of these parameters on the hydrodynamic coefficients, so in this study, experimental tests and collect data using sensitivity analysis, the weight of each parameter and the interaction of parameters surface-piercing propeller to evaluate the hydrodynamic coefficients on the propeller thrust, propeller torque, and therefore performance, is desired. Based on the results obtained, the parameters of step angle, skew and compared to other parameters, have the greatest impact in changing the propeller efficiency, while changing the ratio Immersion, the change will have little impact on efficiency and propeller.
  • Detection coastal thermal fronts in the Persian Gulf and the Oman Sea using MODIS images

    Karami, H.; Akbarinasb, M.; Safarad, T. (2018)
    Temperature fronts are important in marine studies. Sea fronts are sharp boundaries between different water masses. For this study different time series of MODIS level-3 thermal IR SST data from 2013-2014 has been processed and thermal fronts the of Persian Gulf and the Oman Sea (47.6°E to 67.7°E and 18°N to 31°N) region mapped using the method, the Canny algorithm and Gaussian filter. Monthly thermal front images of this region are mapped during the period of January 2013 to June 2014 are classified into Summer Monsoon (June, July, August, September), Winter Monsoon (October, November, December, January) and Pre Monsoon (February, March, April, May) periods and their characteristics are discussed here. The results show that high frequency of SST fronts was observed in the Oman Sea and Persian Gulf in October, November, December, January and May in 2013 year and January, November and December in 2014 year. The number of fronts increases since the beginning of winter to early spring and the beginning of fall, too. The remaining these fronts move with current toward the Arabian Sea and Indian Ocean at the beginning of the summer monsoon. Sustainable and cohesive front was seen near the Arvand River in the Persian Gulf that is presents in the cold months more. This front will disappear in the months of July, August and April 2013 and 2014. The other stable front is in the Oman Sea in southern Pakistan. Most of the front are presenting in the warmer months of June, September, October in 2013 and in June, August and October in 2014.
  • Survey on parasite infection of two years old carp bream, Abramis brama, to Ligula intestinalis in Alagol lake and Gorganroud (Golestan dam) - Golestan province

    Mazandarani, M.; Hoseini, A.; Hajimoradloo, A.M. (2018)
    To evaluate the infection of carp bream (Abramis brama) with ligula intestinalis in Golestan province, 92 fish samples from two regions: Gorganroud (61 samples) and Alagol lake (31 samples) were investigated. According to the result in the present study, the prevalence of ligula intestinalis plerocercoid infestation in carp bream from Alagol Lake for male, female and overall (male and female) were 5.88%, 7.14% and 6.45%, respectively, also in the Gorganroud river for male, female and overall (male and female) were recorded as 22.22%, 26.47%, and 24.59%, respectively. Based on the statistical analysis, the prevalence of this parasite in fish specimens from the Gorganroud was recorded significantly higher than Alagol lake`s specimens. In this study, the mean intensity ± SD of parasite infestation for carp beam in Alagol Lakes and Gorganroud were recorded as 2.5 ± 2.1 and 2.00 ± 1.25, respectively. There was no significant difference in mean intensity of ligula intestinalis infection between two mentioned regions (P<0.05). The length of isolated and number of isolated parasites for each infected fish was different between 6 -64 cm and 1-5 numbers respectively. Totally, mean prevalence and intensity of ligula intestinalis infection for both regions in Golestan province were recorded as: 18.48 % and 2.05 ± 1.25 number (per infected fish) respectively. There was no significant difference between male and female for prevalence and intensity of parasite infection in this study (P<0.05).
  • Genetic Analysis of Sand Whiting Sillago sihama from North Persian Gulf based on Cytochrome Oxidase C subunit I sequences

    Oujifard, A.; Shadi, A.; Fateh, E.; Hosseini, S.J. (2018)
    Silaginidae family fish from Perciforms, are appropriate candidates for shallow water and coastal aquaculture. At least three species of this family represents in the Persian Gulf. Genetic analysis of Sand whiting Sillago sihama , the most common species of family performed using COI gene. During the present study 10 samples were collected from Bushehr and Hormozgan provinces coastal waters. DNA extracted by modified CTAB method. Polymerase chain reactions were performed using universal primers - FISHF1 and FISHR1-. Sequencing results showed a 627 bp amplified fragment. Performing BLAST supported high identity to Sillago sihama species, hence morphometric identification confirms molecular barcoding. Genetic distance of 0.02 was calculated between samples of two areas based on Kimura 2- parameter using Mega software. Constructed phylogenetic tree using neighbor joining method whereas the Acanthopagrus latus sequences was used as an outgroup revealed no differentiation between two stations samples. In conclusion based on the results of the present study, the gene flow was high among studied samples and no significant differentiation was observed between Bushehr and Hormozgan samples. In conclusion no discrete populations differentiated based on the results of the present study.
  • Determination of lethal range and median lethal concentration (LC50 96h) values of diazinon on Caspian Sea common bream (Abramis brama)

    Safahieh, A.R.; Jaddi, Y.; Movahedinia, A.A.; Hallajian, A.; Dezhandian, S. (2018)
    Pesticides are environmental contaminants which normally enter to aquatic ecosystems after being used in aquaculture. In this research, acute toxicity of diazinon was studied on Caspian Sea common bream (Abramis brama). This pesticide may enter in aquatic food chain and cause serious problems for aquatic organisms as well as human. The acute toxicity test was performed during 96h in static renewal system based on the standard method proposed by OECD. A range finding test was carried out in aquariums containing 10L of test solution to determine the lethal range of diazinon on fish. The acute toxicity test was then preformed in 5 treatments and 3 triplicates for each treatment. Obtained data were analyzed using probit analysis with %5 confidence limit. According to the results, LC_50 24h, LC_50 48h, LC_50 72h and LC_50 96h of diazinon on Caspian Sea common bream was 10.974, 10.391, 9.134 and 7.316 respectively. The maximum acceptable toxicant concentration (MATC) of diazinon on Caspian Sea common bream was 0.073 mg/l and the lowest observed effect concentration which is equal to LC_50 96h was 2.63 mg/l. According to the results and comparing with other studies, it can be discussed that Caspian Sea common bream is more resistant against diazinon rather than other fish species. In addition, lethal toxicity of diazinon takes place in a moderate range of toxicant concentrations.
  • Antioxidant and antibacterial assay of two red marine macro-alga of Bandar Abbas coastal

    Zarei Jeliani, Z.; Yusef Zadi, M.; Sohrabipour, J.; Toiserkani, H. (2018)
    Seaweed is favored seafood in some regions and is also used as feedstock for extracting fine chemicals. The total global seaweed production continues to grow This study investigated the biological activities of n-Hexane, Ethylacetate and Methanol extract of two red marine macro algae (Gracilariopsis persica and Hypnea flagelliformis), collected from the coast of Bandar Abbas, Persian Gulf, Iran. For identification the superior species with biological properties, the tested activities included Carotenoids content, total Phenolic content, total flavonoids content, antioxidant activity at the concentration (3 mg/ml) by ferric reducing power (FRP) and total antioxidant capacity (TAC) assay and at final, antibacterial activity was evaluated. This study revealed that the more effective macro algae extracts by maximum antioxidant capacity: FRP and TAC, were recorded for Ethylacetate extracts. The result showed the highest content of phenolic and flavonoid compounds were recorded for the Methanol extracts of Gp. persica, 45.12±0.01 (mg GA/gr DW.) and 2.28±0.007 (mg QE /gr DW.), respectively while H. flagelliformis showed the maximum Carotenoid content 17±0.06 (mg 100g^-1 ). In addition, the highest antibacterial activity was recorded for the n-hexane and followed by Ethylacetate extracts. In general comparison, though, according to the results, antioxidant and antibacterial activity of species in this study were calculated less than standard, but could be accounted these seaweeds as safe biological properties and with abundance of them in coastal of Bandar Abbas, could be considered for future applications in medicine and dietary supplements.
  • Effects of Single and Combined Supplementation of Lactobacillus plantarum with dietary xylooligosaccharide on growth performance, body composition and physiological responses of sobaity (Sparidentex hasta) fingerling

    Morshedi, V.; Agh, N.; Marammazi, J.; Noori, F.; Mohamadian, T. (2018)
    The aim of this study was to evaluate the single and combined effects of dietary probiotic with prebiotic on growth performance, non-specific immune response, body composition, digestive enzymes activity and intestine bacterial flora of sobaity fingerling (Sparidentex hasta). For this purpose, 425 individuals of sobaity fingerlings were prepared with an average weight of 7.64 ± 0.3 g from the Mariculture Research Station of South Iranian Aquaculture Research Center. This study was carried out in a completely randomized design with four treatments and three replications (45 fish per each replication) in fiberglass tanks with 300 liters volume. Fish were fed with feed containing 0 (control group), 10^6 CFU probiotic per gram feed (treatment 1), 0.5 and 1 percent prebiotic plus10^6 CFU probiotic per gram feed (treatment 2 and 3) at 4.5 percent of body weight for a period of 42 days. At the end of the experiment, body composition, intestine, blood, plasma and mucus samples were collected. The obtained results indicated that dietary prebiotic and probiotic did not change growth performance, intestine bacterial flora and non-specific immune response of sobaity (P > 0.05). Nonetheless, plasma bactericidal activity of control group was significantly higher that treatment 3 (P < 0.05). Moisture and protein content of treatment 2 showed significant different compared to the control group (P < 0.05). The results of this study showed that digestive enzymes activity including alkaline protease, amylse and lipase affected by administration of dietary prebiotic and probiotic (P < 0.05). Overall, this study showed that single supplementation of probiotic and combination with prebiotic at the used amounts had no positive effects on growth performance and intestine bacterial flora and immune response (except plasma bactericidal activity) of sobaity but improve digestive enzymes activity.
  • Molecular and phylogenetic investigation of Chiromantes boulengeri (Decapoda, Brachyura, Sesarmidae) species from Arvand River

    Nozarpour, N.; Nabavi, M.B.; Ronagh, M.T.; Archangi, B.; Sakhai, N. (2018)
    In this study, the molecular characteristics of Chiromantes boulengeri were investigated from intertidal waters of Arvand River, Minoo Island in 2014. For this reason, samples from intertidal zones of two areas across Minoo Island were collected and preserved in 70% ethanol, followed by transferring to the laboratory for further examinations. Genomic DNA was extracted using phenol- chloroform method and mitochondrial gene 16SrRNA was sequenced and compared with other species from GenBank NCBI. The morphological examinations using identification keys and phylogeny sequence results showed that all specimens belonged to Chiromantes boulengeri in the study area. Phylogenetic analysis revealed that there are mutation within C. boulengeri from two areas of Arvand River. It seems that, this species most probably is adapted to the different ecological conditions in this area.
  • Prediction of suspended sediment distribution of Karoon River using artificial neural network

    Bahrami, H.; Emamgholi Zadeh, S. (2018)
    Accurate estimation of sediment concentrations in hydraulic sediment transport from different viewpoint such as sediment discharge estimation of river, selection of hydraulic structures and etc. are important. With respect to importance of this issue in this study for prediction of sediment concentration of Karun river multi-layer perceptron artificial neural network (ANN / MLP) was used. For this purpose 125 field data including bottom concentration, flow velocity, nearest distance from the beach, and the total depth of flow and flow depth was used. Three statistical metrics namely mean absolute error (MAE), root mean square error (RMSE) and coefficient of determination (R^2 ) were used to evaluate the performance of ANN model. The result shows that MLP model with one hidden layer, Sigmoid transfer function and 5 neurons have best structure in the modeling of sediment concentration of Kroon River. The R^2 and RMSE value is equal to 0.953 and 63.37 mg/l in training stage and 0.752 and 203.02 mg/l in testing stage, respectively. Finally, the sensitive analysis also showed that the nearest distance from the beach and flow depth had the most and the least effect on the sediment concentration, respectively.
  • Study of temperature-curvature relationships in Bi-stable Composite Laminates

    Moore, M.; Firouzian-nejad, A.; Ziaei-Rad, S.; Eidani nezhad, A. (2018)
    The interest in bi-stable structures comes from their ability that these structures can have two different stable equilibrium configurations to define a discrete set of stable shapes. The geometrical changes occur with no need to continuously consume power, and mechanical hinges to preserve the structure in each stable shape. It is known that asymmetric composite laminates can have bi-stable response to different kind of loadings. In this research, the non-linear temperature-curvature relationship for the asymmetric composite laminates is studied using Rayleigh–Ritz technique. Attention is focused on studying the effect of material temperature dependency and resin layers; especially in the bifurcation point by use of analytical method. To this end, the well-known analytical theories are extended and used to consider the temperature dependency of material. The results obtained from the theory are then compared with the finite element simulations results and a good correlation is obtained. Finally, an experimental investigation is carried out and several specimens with [90/0]T, [70/–20]T and [70/20]T compositions were manufactured. In order to study the effect of resin layers, optical microscopy is utilized and the exact thickness of different layers in the manufactured specimens is determined. The thermal responses of the manufactured plates were measured and used to validate the results obtained from the analytical theory and finite element simulations.
  • Population Structure of Caspian Roach (Rutilus Rutilus caspicus) in Southern Coasts of Caspian Sea using Microsatellite Maker

    Kashiri, Hadis; Shabani, Ali; Shabanpour, Bahareh; Razaei, Mohammad (2012)
    Caspian roach is regarded as a valuable bony fish that has economic importance in southern parts of Caspian Sea. Investigations show that natural reproduction of this species has been declining during recent years. Restocking of this fish is achieved by the way of artificial reproduction. Loss of genetic stock of this species is of great concern. In the current study, in order to study the population structure of roach, 54 individuals were captured from Gomishan and Anzali wetlands (27 individuals from each region) in April 2007. Genomic DNA was extracted using phenol-chloroform method and investigated by 10 microsatellite loci. The genetic diversity of two regions [(Gomishan: average number of alleles, Na= 11.4, average effective number of alleles, Ne= 7.92, observed heterozygosity, Ho= 0.69 and expected heterozygosity, He= 0.85) (Anzali: Na= 10.2, Ne= 7.38, Ho= 0.71 and He= 0.84)] were not statistically different (P>0.05). Analysis of molecular variance showed high genetic diversity (%95) within populations. The Fst value was 0.046, indicating low genetic differentiation among Anzali and Gomishan regions. In this study, 10 of 20 (10 loci × 2 populations) tests showed significant deviation (P≤ 0.005) from Hardy-Weinberg equilibrium due to the heterozygosity deficiency. Results from UPGMA cluster analysis, based on Nei´s genetic distance, showed that the regions are probably separated from each other.
  • Study of Genetic Diversity of Hara Trees on the Coast of Hormozgan Province Using Rapid Molecular Method

    Ghanavati Mohammad Ghasemi, Iman; Zolgharnein, Hosein; Khaledi, Hoda (2015)
    In order to study the genetic diversity of Hara trees in the coastal waters of Hormozgan province, using 40 RAPD molecular samples, 40 samples of Hara leaves were collected at different stations (ports of Jask, Dumitry, Tiba and Qeshm Island) and transferred to the laboratory. After extraction of DNA They were examined by 30 primers in polymerase chain reaction. The results showed that the highest mean genetic variation in Qeshm population was 0 458 with a standard deviation of 0.033 and the lowest mean of genetic diversity in Jask population was 0.423 with a standard deviation of 0.056. Also, using the PopGene software, the average Shannon information index was 0.643 for four populations. The value of Fst index was 011/0 and the gene flow rate was 25.854, and the UPGMA dendrogram, based on the Nei genetic distance, did not show a clear separation between the populations. Also, molecular variance analysis showed that there is a high variation (99%) within the studied populations. The results of this research can provide useful information for conservation and management programs of this kind with indigenous value of Iran.
  • Investigation of reproduction carachretistics of Cobitis taenia in southern costal of Caspian Sea

    Bahrebar, Soheil (2014)
    Cobitis taenia is one of the index samples and as apart of benthal fishes in the waters southern costal of Caspian Sea. In total 410 Cobitis taenia were caught. Sampling has been done by electroshocker 300 V, monthly and during one year since Oct. 2008 up to Sept. 2009 According to condition of sampling, the sum of two stations sampled monthly between 16 to 50 and has been distinguished randomly at two Kaselian and Tajoon stations of stuaries of Kazar sea. Average egg diameter of fish by Measured in the Loop was highest in April and this trend continued until May, and the average diameter in April was 36.20 Micron with SD 6.52. Investigation showed that the gonads of these fishes at sexual maturity occurs in April. Average percentage of sexual maturity index (GSI) 1.04%, respectively with SD 0.42. Average liver weight index (HSI) equal to 0.156 with SD 0.009 was calculated, so that the peak time of sexual maturity, we see a reduction in liver weight. Total length of fish at the time of sexual maturity (Lm50), with an average 67.44 mm, SD 11.17 and average weight 2.33 g and SD 0.64 was calculated. The HSI (liver weight) in spring than in other months showed a significant reduction in the loss is inversely proportional to the amount of GSI in this chapter.
  • Distribution Patterns of Rocky Shore Crustacea in the Hormuz Island.

    Mirzabagheri, Dara; Nabavi, S.M.B.; Mehvari, Alireza; Karami, Kambiz (2014)
    A general description of distribution patterns of rocky shore cructacea along the Hormuz Island coasts is presented to provide the context for comparisons of distribution patterns of this intertidal organisms. In order to test if there was any variation in species distribution and abundance from upper to lower intertidal zone (littoral zone) along the entire rocky shores of the Hormuz Island, three main regions (west, south and south-eastern) were studied and 3 transects were sampled in each region. At each one of the 9 transects the shore was levelled and a general qualitative description was made, which also aided grouping of subsequent quantitative sampling. Photographs and slides were taken from the live specimens and then specimens were fixed in 4% formalin and transported to lab for analyses. The upper zone was characterized by the presence of Balanus amphitrite. The midlittoral zone was essentially dominated by Balanus amphitrite. The distribution patterns observed on the lower zone showed a similarity between rocky shores located in south and south-east of the Hormuz Island dominated by Elasmopus sp.. It has also provided important information on abundance and seasonal distribution of cructacea in rocky shores of the Hormuz Island. According to the results abundance of cructacea was markedly lower in Summer compared to Winter. In conclusion species of cructacea is prevailing and environmental conditions and bed is the main reason for high abundance of this class. Distribution of crustacean is mainly affected by prevailing environmental conditions and the substratum type.
  • Numerical Modeling and Estimation of Renewable Energy of Tidal Current in Khoore Musa

    Mahmoudaf, Masoud; Chegini, Vahid (2014)
    In this article, two three-dimensional hydrodynamic and numerical models, COHERENS and BOM are used to investigate the renewable tidal energy in Khoore Musa. Firstly, the effect of 6 tidal constituents on regional hydrodynamic is estimated in 10 sigma levels in vertical and 250 resolution. The results of both models are verified with field data recorded by Iranian National Institute for Oceanography. It is found that the outcomes of COHERENS are more reliable but calibration is required. Whereas the accuracy of calibrated hydrodynamic module of COHERENS is approved, the energy of tidal currents is calculated. In this study, the current energy module is developed and set as a supplementary module. Hourly averaging of current energy during one month indicated that the maximum value recorded was more than 0.65 MWh. The maximum depth-integrated energy of this area was about 5 MWh. The best and more advantageous area to extract energy is a strait in the Middle-Bar with density of more than 300.
  • Effects of environmental factors on distribution of sea cucumbers in subtidal region of Chabahar Bay

    Shakouri, A.; Nabavi, S.M.B.; Kochanian, P.; Savari, A.; Safahiye, A.R. (2014)
    Considering the importance of environmental factors on marine organisms, a survey of factors that affect the subtidal sea cucumber community was carried out in the eastern part of Chabahar Bay, a region with anthropogenic effects on marine ecosystem, from May 2007 to July 2008. Four quadrates with 100m2 area were sampled with SCUBA diving method in each region. Temperature had significant variation among the stations and seasons. There is a positive correlation (99%) between salinity and sea cucumber density and a negative correlation (95%) between turbidity and density. PCA indicated that salinity, pH, turbidity and temperature had 82.78% of all variance of the environmental factors and other factors did not exhibit such a relation with sea cucumber dispersion. Northern stations (Sepah and Kalantary) were located in same category in Fall 2007 and Winter 2008. These stations had the least pH and the highest salinity and turbidity in Fall and the highest pH and the least turbidity in Winter. Southern stations (Beheshti and Hotel Daryai) located in the same category in summer and fall 2007. These stations had the most pH and the least salinity in the summer and the most temperature and turbidity in the fall.
  • Histological characterization of venom secretory cells in the stinger of 3 stingrays (Dasyatidae) species: Dasyatis bennetti, Himantura walga, Himantura gerrardi, in northern water of Persian Gulf and Oman Sea

    Dehghan, Hadi; Sajjadi, Mir Masoud; Parto, Paria; Rajaian, Hamid; Jalaei, Jafar (2014)
    Rays are common elasmobranches in the northern waters of Persian Gulf and Oman Sea that may have one or more mineralized serrated stingers on the whip-like tail. The stingers are covered by epidermal cells among which some can produce venom. When these animals are dorsally touched, the stinger may be introduced into the aggressor by a whip reflex mechanism, causing severe mechanical injuries and inoculating the venom. A comparative morphological characterization of the stinger epidermal tissue of different ray species in the northern part of Persian Gulf and Oman Sea was carried out in this study. EDTA was used for decalcification of stings and conventional histological processes were subsequently employed. The results indicated that structure of dermis and epidermis layers of stings in all species are similar to those of corresponding layers in other parts of fish’s body. The results of the present study have also shown that all three examined species, had venom secretory cells. Distribution of venom secretory cells varies in each species; in Dasyatis bennetti and Himantura walga species, these cells presented in all covered epithelium of stings and in Himantura gerrardi, were in the ventral, ventro-lateral and dorso-lateral of the spine. These differences among the stingers of various species may explain the envenomation severity in these species.

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