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Dorsal Fin (dorsal + fin)
Selected AbstractsIndependent induction and formation of the dorsal and ventral fins in Xenopus laevisDEVELOPMENTAL DYNAMICS, Issue 3 2004A.S. Tucker Abstract It has been known since the 1930s that the dorsal fin is induced by the underlying neural crest. The inducer of the ventral fin, however, has remained elusive. We have investigated the source of the inducer of the ventral fin in Xenopus and show that it is the ventral mesoderm and not the neural crest. This induction takes place during mid-neurula stages and is completed by late neurulation. In terms of cell composition, the dorsal fin mesenchyme core arises from neural crest cells, while the mesenchyme of the ventral fin has a dual origin. The ventral fin contains neural crest cells that migrate in from the dorsal side of the embryo, but a contribution is also made by cells from the ventral mesoderm. Developmental Dynamics 230:461,467, 2004. © 2004 Wiley-Liss, Inc. [source] Predation risk allocation or direct vigilance response in the predator interaction between perch (Perca fluviatilis L.) and pike (Esox lucius L.)?ECOLOGY OF FRESHWATER FISH, Issue 3 2005A. Vainikka Abstract , Predation risk allocation hypothesis predicts that a prey's response to predator depends on prey's previous experience on predator. Here we tested whether the group of three perch respond differentially to pike, predator of perch, depending on the timing of high constant (HC) and high unpredictable (HU) risk periods within low constant risk periods in short-term (10 h) experiments, and whether the response is stronger during a HU risk period than during a HC risk period. Perch clearly erected the dorsal fin in response to predation risk treatments (pike odour only, odour and visible pike). Decrease in activity and increase in shoaling behaviour were observed mainly during high risk periods. However, the perch's responses to pike did not differ statistically between periods of various levels of predation risk or depending on the timing of high risk situations within constant low risk periods, and thus, suggesting that perch respond mainly to changes in the current predation risk. Resumen 1. La hipótesis de la asignación de riesgo a la predación predice que la respuesta a un predador depende de la experiencia previa de la presa al predador. En este trabajo analizamos si un grupo de tres individuos de Perca fluviatilis respondían de forma distinta a la presencia de Esox lucius, (un predador común de esta especie) y si éstas dependían del momento en el que se producen periodos de alto riesgo constante y de alto riesgo impredecible, en experimentos de corto plazo (10 horas) de riesgo bajo y constante y si la respuesta era mayor durante perí odos de riesgo impredecible y alto que durante períodos de riesgo constante alto. 2. Claramente P. fluviatilis respondió levantando la aleta dorsal en respuesta a los tratamientos de riesgo a la predación (solamente olor y olor + visibilidad de E. lucius). Una menor actividad y una mayor tendencia a la formación de bancos fueron observados durante períodos de alto riesgo. Sin embargo, las respuesta de P. fluviatilis a E. lucius no difirieron estadísticamente entre períodos de varios niveles de riesgo a la predación o entre aquellos que dependieron del momento en el que se produjeron situaciones de alto riesgo dentro de períodos de bajo riesgo constante. 3. Concluimos que P. fluviatilis puede utilizar señales olfatorias como determinantes de respuestas al riesgo a la predación y responder a aumentos de riesgo, sin excluir la posibilidad de que amenazas repetidas decrezcan la intensidad de la respuesta. Nuestros resultados, obtenidos en experimentos realizados a pequeña escala temporal, no niegan la posibilidad de la P. fluviatilis y otras especies puedan balancear la alimentación con actividades anti-predación, de acuerdo a cambios en el riesgo de predación a lo largo de escalas temporales de varios días. [source] A juvenile Early Carboniferous (Viséan) coelacanth from Rösenbeck (Rhenish Mountains, Germany) with derived postcranial charactersFOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 2 2010Florian Witzmann Abstract A small coelacanth specimen of Viséan age from a newly described locality near Rösenbeck at the northern margin of the Rhenish Mountains (North Rhine-Westphalia, Germany) is described. The head and pectoral girdle are not preserved, however, the specimen can be distinguished from all other known Carboniferous coelacanths by derived characters of the articulated postcranial skeleton. Derived characters include: (1) The slender first and second dorsal fins that carry only seven to eight and six fin rays, respectively. (2) Both the pelvic and anal fin have a broad base and are unusually weakly lobed. (3) The fin rays of the second dorsal fin are much more robust than those of the first dorsal fin. (4) The second dorsal and anal fins are longer than the first dorsal and pelvic fins. The Rösenbeck coelacanth is interpreted as a juvenile specimen, since the basal plates that support the fins are not ossified. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Variability of tilapias (Oreochromis spp.) introduced in Mexico: morphometric, meristic and genetic charactersJOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2004I. D. L. A. Barriga-Sosa Summary In Mexico, the tilapia Oreochromis provides one of the most important sources of animal protein and income in a wide variety of communities throughout the country, however, their culture and production face severe problems because of lack of management information. Evaluated in the present study is the degree of morphological, meristic and allozyme variation of two tilapia strains, two species and one hybrid from two important reservoirs in Mexico, two tilapia fry production farms (TFPF) and an experimental production system (EPS), to diagnose the actual status and degree of variation among them. Twenty-two presumptive loci were utilized to determine the genetic variation, structuring and distances among samples. Multivariate analyses of 11 meristic and 33 morphometric characters were also evaluated, including the distance from the end of the mouth opening to the most anterior dorsal fin (0.9894), distance from the anal fin base to the anterior part of the caudal fin (0.9845) and the base length of the dorsal fin (0.9839) which contributed to the separation of groups. The canonical discriminant functions for the morphometric and meristic variables show that the correct classification of the organisms in percentages and in the sites of origin was on average 72%. The tilapia from the reservoirs and the experimental production system had higher genetic variations than tilapia from the fry production farms (average He 0.310, 0.062, 0.151 for Metztitlan, Infiernillo and EPS, respectively, vs 0.024 and 0.000 for Los Amates and Zacatepec, respectively). The genetic data indicate that fishes of the TFPF should be monitored closely, as they are the main source of dispersion to the reservoirs. Present results show that these data could be a fast and reliable aid to the fisheries and management of tilapia in Mexico. [source] Efficacy of in-feed probiotics against Aeromonas bestiarum and Ichthyophthirius multifiliis skin infections in rainbow trout (Oncorhynchus mykiss, Walbaum)JOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2008N. Pieters Abstract Aims:, The aim of this study was to assess the efficacy of in-feed probiotics as a preventive measure against skin infections caused by Aeromonas bestiarum and Ichthyophthirius multifiliis (Ich) in rainbow trout. Methods and Results:, Fin rot was induced in fish by intradermal injection with 0·1 ml volumes containing 105 cells per ml A. bestiarum at the base of the dorsal fin. Ich infections resulted from immersion in Ich-contaminated water. Each probiotic was administered orally [108 cells per g feed for GC2 (Aeromonas sobria) and 1010 cells per g feed for BA211 (Brochothrix thermosphacta)] for 14 days. Results showed that, after challenge with A. bestiarum, probiotics GC2 and BA211 led to 76% and 88% survival, respectively, in contrast to 22% survival for controls. Fish fed with probiotic GC2 had 100% survival after challenge with Ich compared with 2% for probiotic BA211 and 0% for controls. Analysis of innate immune responses revealed that probiotic GC2 promoted higher phagocytic activity, whereas probiotic BA211 led to enhanced respiratory burst activity. Conclusion:, Of the two probiotics examined, GC2 was more effective in protecting against both fin rot and Ich. Each probiotic appeared to stimulate different pathways within the innate immune system. Significance and Impact of the Study:, This is the first demonstration that probiotics can protect fish against surface infections. Furthermore, this is the first time a probiotic has been shown to protect against a eucaryotic pathogen, namely I. multifiliis. [source] Description of a new cichlid fish species of the genus Benthochromis (Perciformes: Cichlidae) from Lake TanganyikaJOURNAL OF FISH BIOLOGY, Issue 3 2008T. Takahashi Benthochromis horii, a new cichlid species is described based on 19 type specimens from the deep waters of Lake Tanganyika. It differs from its congeners by having smaller eyes and longer snout (eye length usually shorter than snout length v. equal to or longer than snout length in Benthochromis tricoti and Benthochromis melanoides), and more dorsal fin rays (total number of spines and soft rays in dorsal fin usually 30 or 31 v. usually 28 or 29 in B. tricoti and B. melanoides). Large males of the new species differ from those of congeneric species in terms of their body colour pattern and long pelvic fins. This species has been confused with B. tricoti and has been traded as an aquarium fish. [source] First record of saddleback syndrome in wild parrotfish Sparisoma cretense (L., 1758) (Perciformes, Scaridae)JOURNAL OF FISH BIOLOGY, Issue 3 2008G. Koumoundouros The saddleback syndrome is recorded for the first time in a wild fish population of the Mediterranean Sea. The deformed specimen belongs to Sparisoma cretense and presents the typical saddleback phenotype of missing spines in the dorsal fin. [source] Description of a new Lake Tanganyikan cichlid fish of the genus Cyprichromis(Perciformes: Cichlidae) with a note on sexual dimorphismJOURNAL OF FISH BIOLOGY, Issue SB 2006T. Takahashi Cyprichromis coloratus, a new cichlid species, is described based on 41 type specimens from the Zambian coast of Lake Tanganyika. It differs from Cyprichromis microlepidotus by having fewer scales in the longitudinal line (41,44 v. 59,70 in C. microlepidotus) and upper lateral line (31,36 v. 47,59), from Cyprichromis leptosoma by more dorsal-fin spines (14,15 v. 11,13 in C. leptosoma) and longitudinal line scales (41,44 v. 38,40), from Cyprichromis pavo by fewer dorsal-fin spines and soft rays (29,31, usually 30, in total v. 30,32, usually 31, in C. pavo), and from Cyprichromis zonatus by shallower body depth [24·0,28·5 (26·4 ± 1·1)% of standard length v. 24·5,30·5 (28·4 ± 1·3)% in C. zonatus] and smaller eye [eye length 25·2,30·9 (27·2 ± 1·1)% of head length v. 27·9,33·3 (30·2 ± 1·2)%]. The new species is also separable from C. microlepidotus, C. pavo and C. zonatus by absence of distinct small spots on the body (v. pearl grey and yellowish small spots along scale rows on body at least in males of C. microlepidotus and C. pavo), its distinct dichromatism (particularly on the caudal fin) between males of the same population (v. dichromatism absent in C. zonatus) and absence of vertical bands (v. three or four distinct vertical bands beneath dorsal fin base in live males of C. zonatus). Cyprichromis coloratus n. sp. also exhibits sexual dimorphism, females having a larger head and males having longer pelvic fin, differences which are discussed in relation to reproductive behaviour. A key to the five species of Cyprichromis is included. A lectotype is designated for Cyprichromis leptosoma. [source] Impact of Background on Color Performance of False Clownfish, Amphiprion ocellaris, CuvierJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 6 2009Inayah Yasir Color performance of false clownfish, Amphiprion ocellaris, Cuvier was first examined at four color backgrounds (blue, green red, and white) for 4 wk, then all fish were transferred to a white background for another 4 wk to test whether the impact of background colors on fish skin could have a lasting effect when the environment colors are changed. The experiment was conducted in 10-L rectangular plastic buckets with three replicates. Thirty fish were stocked in each bucket and three fish were randomly sampled from each tank in Weeks 1, 4, and 8. The color hue, saturation, and brightness were quantified using image analysis. In addition to the whole body analysis, each fish image was divided into ventral and dorsal parts to examine the body position-dependent response. Furthermore, color differences among the dorsal fin, anal fin, ventral fin, and caudal fin were also quantified. Blue or green background enhanced red orange color on fish skin, whereas white background made fish color brighter. Irrespective of background color, the dorsal side of fish exhibited more red orange, but the color was less bright and less saturated than that of ventral side. Upper fins (dorsal and caudal fins) were more red orange in a blue background than in a white background. Transferring fish from colored backgrounds to a white background made the fish skin and fins brighter, the color of ventral body and ventral fins less saturated, and the bottom fins more yellow orange. The results indicate that blue or green background could strengthen the orange color, whereas white background made fish color less saturated but brighter. The impact of background on the performance of fish color is temporary and likely to disappear when environmental color changes. [source] Effect of Light Intensity on Color Performance of False Clownfish, Amphiprion ocellaris CuvierJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2009Inayah Yasir Color performance of false clownfish, Amphiprion ocellaris Cuvier, was examined under three levels of light intensity (20,50 , 600,850 , and 2700,3500 lx) for 5 wk. The experiment was conducted in nine rectangular glass aquaria (25 × 25 × 20 cm) with three replicates. Each aquarium was stocked with 36 fish, and 3 fish were randomly sampled from each aquarium every other week. Digital images were taken weekly on each individual fish after it was anesthetized in MS-222. The color performance in hue, saturation, and brightness was quantified using image analysis. In addition to the whole-body analysis, each fish image was divided into ventral and dorsal parts to assess the body position-dependent effect. Furthermore, color differences between dorsal fin, anal fin, ventral fin, and caudal fin were also quantified. The whole body was brighter at low light than at medium or at high light intensity. Irrespective of light intensity, the dorsal side was more orange but less bright than the ventral side. Brighter light strengthened overall orange color on fish fins. The dorsal fin and ventral fins appeared more orange than the anal and caudal fins regardless of light intensity and exposure duration. Similar to body color, low light also led to brighter fins, especially for caudal and dorsal fins. Our results indicate that ambient light could regulate fish color performance but could not change the pigment dominance by ,-carotene. Light intensity is unlikely to change the contrast between dorsal and ventral sides, but dim light tends to make fish body brighter, and bright light strengthens orange color on fins. [source] Blubber testosterone: A potential marker of male reproductive status in short-beaked common dolphinsMARINE MAMMAL SCIENCE, Issue 3 2009Nicholas M. Kellar Abstract A novel molecular technique was used to measure blubber testosterone (BT) in 114 male short-beaked common dolphins, Delphinus delphis, collected from incidental fishery bycatch and strandings. When these concentrations were compared across maturity states, the mean (± SEM) BT levels of mature D. delphis (14.3 ± 3.0 ng/g) were significantly higher than those of pubertal (2.5 ± 0.5 ng/g, P= 0.006) and immature animals (2.2 ± 0.3 ng/g, P < 0.0001). BT concentrations in mature males were significantly higher in summer months (53.9 ± 2.0 ng/g) than during the rest of the year (7.9 ± 0.69 ng/g, P < 0.0001), indicating reproductive seasonality. An analysis of BT in different anatomical locations showed that hormone concentrations were not homogenous throughout the body; the levels in the dorsal fin were significantly lower than in most other areas (F= 5.39, P= 0.043). Conversely, we found no significant differences in BT concentration with respect to subepidermal depth (F= 2.09, P= 0.146). Finally, testosterone levels in biopsies from 138 free-swimming male D. delphis, of unknown maturity state, sampled off California were found to be of concentrations similar to those from the fishery bycatch and stranding samples and revealed an analogous trend with respect to ordinal date. [source] REACTIONS OF CAPTIVE HARBOR PORPOISES (PHOCOENA PHOCOENA) TO PINGER-LIKE SOUNDSMARINE MAMMAL SCIENCE, Issue 2 2006Jonas Teilmann Abstract Pingers on gill nets can reduce bycatch of harbor porpoises. If harbor porpoises habituate to pingers, the effect may be reduced or lost. Two captive harbor porpoises were exposed to three sound types. All sounds were in the frequency band from 100 kHz to 140 kHz, 200 ms long, and presented once per 4 s. The source level was 153 dB re 1 ,Pa RMS at 1 m. Each session consisted of a 10-min presound, a 5-min sound, and a 10-min postsound period. Behavior was recorded on video and on dataloggers placed on the dorsal fin of one animal. The loggers recorded heart rate, swimming speed, dive duration, and depth. The animals responded most strongly to the initial presentations of a sound. Surface time decreased, the heart rate dropped below the normal bradycardia, and echolocation activity decreased. The reactions of both animals diminished rapidly in the following sessions. Should the waning of responsiveness apply to wild animals, porpoises may adapt to the sounds but still avoid nets, or the bycatch may increase after some time. The success of long-term use of pingers may then depend on the variety of sounds and rates of exposure. [source] DOES RADIO TAGGING AFFECT THE SURVIVAL OR REPRODUCTION OF SMALL CETACEANS?MARINE MAMMAL SCIENCE, Issue 1 2006A TEST Abstract A long-term study of botos (inia geoffrensis) in the Brazilian Amazon permitted the comparison of survival and reproduction between 51 adults fitted with radio transmitters and an equal number that were captured and handled in the same way but released without a transmitter. For both sexes combined, 47 radio tagged botos (92.2%) survived at least three years after release compared with 42 (82.4%) without radios, equating to annual survival of 97.3% and 93.6% respectively. The difference was not statistically significant. Eight of 15 closely monitored radio tagged females were lactating at capture, and all their calves weaned successfully. Two that were pregnant at capture subsequently gave birth. The mean number of calves per year born to these 15 females after first release was 0.172 (SD = 0.107) and to 17 non-tagged was 0.174 (SD = 0.095), again a non-significant difference. These results indicate that the anchoring of packages to the dorsal fin of dolphins can be accomplished with no measurable impact on their subsequent survival or reproductive output. However, botos may be unusually robust to handling, and this study should not be used to justify using similar techniques on other species without customary caution, diligence, and expert guidance. [source] SEXUAL ECOLOGY OF THE SPINNER DOLPHIN, STENELLA LONGIROSTRIS: GEOGRAPHIC VARIATION IN MATING SYSTEMMARINE MAMMAL SCIENCE, Issue 3 2003William F. Perrin Abstract We offer the first report for a cetacean of geographical variation in mating system based in morphology. Analysis of samples from 1,678 male spinner dolphins from the eastern Pacific revealed that testis + epididymis weight was greater (to 1,354 g) in the whitebelly form of the species than in the eastern form (to 843 g). Sexual dimorphism in dorsal-fin shape is greater in the eastern form. The difference in testis size was strongly linked with shape of the dorsal fin on an individual basis. Only a few eastern males (0.6%) reached testis + epididymis weight at which all epididymides contain sperm, while a much larger proportion of whitebelly spinners (15.2%) reached this level, suggesting that a smaller proportion of eastern spinner males may participate in reproductive activity. This, and the fact that increased dimorphism and decreased testis size are indicative of increased polygyny in a wide variety of other mammal species, leads to the conclusion that the mating system varies geographically in the species, with a gradient from a more polygynous mating system in the eastern form to a more open or polygynandrous mating system in the whitebelly form. Differences in ovulation rate in the two forms are consistent with this conclusion. [source] STATUS, RELATIONSHIPS, AND DISTRIBUTION OF MESOPLODON BOWDOINI ANDREWS, 1908 (CETACEA: ZIPHIIDAE)MARINE MAMMAL SCIENCE, Issue 3 2001Alan N. Baker Abstract The specific status of Mesoplodon bowdoini Andrews is reviewed and new information on its morphology, reproduction, and distribution is presented. This species of beaked whale, known only from 35 specimens, has a southern, circumpolar distribution north of the Antarctic convergence, between 32° and 54°30,S. It shares with M. bahamondi Reyes, Van Waerebeek, Cárdenas and Yáñez from the south Pacific Ocean including New Zealand (this paper) and M. carlhubbsi Moore from the north Pacific, a number of morphological features such as prominential notches in the maxillary bones in the skull. It is less similar to M. stejnegeri True from the north Pacific and M. ginkgodens Nishiwaki and Kamiya from the tropical Indo-Pacific. Mesoplodon bowdoini can be distinguished from all other species of Mesoplodon by the shape of its teeth (male and female), and differences in the morphology of its skull, especially the proportions of the rostrum, separation of the nasals, the shape of the prominential notches, and the nature of the antorbital processes. The species' distinguishing external characteristics are: a robust body up to about 4.50 m long; a low melon and short, thick beak; an elevated jawline posteriorly; and a low, blunt-tipped, triangular dorsal fin. The occurrence of fetuses of M. bowdoini in May and September, and perinatal juveniles in May and June, indicates a summer-autumn breeding season in the New Zealand region; the length at birth is estimated at about 2.20 m. [source] PHOTOGRAPHIC IDENTIFICATION OF NORTHERN BOTTLENOSE WHALES (HYPEROODON AMPULLATUS): SOURCES OF HETEROGENEITY FROM NATURAL MARKSMARINE MAMMAL SCIENCE, Issue 1 2001Shannon Gowans Abstract The use of natural marks in capture-recapture studies can lead to unequal capture probabilities. This paper examined a catalog of northern bottlenose whale (Hyperoodon ampullatus) photographs from the Gully, Nova Scotia, to identify potential sources of heterogeneity. This information can be used to select appropriate individuals and photographs to include in analyses. Individual northern bottlenose whales were sufficiently marked to uniquely identify individuals (x,= 14.5 marks/individual; range 1-67), but not all mark types persisted over time. Reliable marks were defined as mark types that were not lost over the nine-yeat study period (notches, back indentation, and mottled patches). Individuals were considered reliably marked if they possessed at least one back indentation or mottled patch (located within one dorsal fin width, at the base of the dorsal fin) or a notch on the dorsal fin. Sixty-six percent (SE = 5%) of the population were reliably marked. Longterm analyses (months to years) should use only reliably marked individuals, and the results scaled to account for the rest of the population. Our results also showed that photographic quality affected an observer's ability to identify individuals. For this catalog, quantitative analysis indicated only photographs of Q , 4 (on a 6-point scale with 6 representing the highest quality) should be included in mark-recapture analyses sensitive to heterogeneity. [source] Muscle Cellularity at Cranial and Caudal Levels of the Trunk Musculature of Commercial Size Sea Bass, Dicentrarchus labrax (Linnaeus, 1758)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2005I. Abdel Summary In eight specimens of Atlantic sea bass of commercial size (,350 g) muscle cellularity was studied at two selected sampling levels of the trunk axial musculature: caudal (anal opening) and cranial (fourth radius of the dorsal fin). The following parameters were quantified at both sampling levels: white muscle cross-sectional area, white muscle fibre diameter (900,1200 fibres), muscle fibre number and muscle fibre density. Results showed a higher total cross-sectional area at cranial than at caudal level (P < 0.05), what is related with their different gross morphology. However, the white muscle fibre size distribution, as well as the muscle fibre number and density did not show significant differences between them. This study contributes to typify muscle fibre sampling in sea bass of commercial size what is of great interest for morphometric studies where white muscle cellularity is commonly correlated with textural or organoleptic parameters. [source] Genetic basis of pectoral fin deformities in the African catfish Clarias gariepinus (Burchell, 1822), Heterobranchus longifilis (Valenciennes 1840) and their hybridsAQUACULTURE RESEARCH, Issue 1 2001P O Aluko Abstract Morphological aberrations of the pectoral fins in nine mating combinations involving Clarias gariepinus (Burchell, 1822), Heterobranchus longifilis (Valenciennes, 1840) and their hybrids were investigated to determine the level and genetic basis of occurrence. The highest mean percentage survival in a Clarias×,Clarias group was 75%, whereas the least mean percentage survival was 2% in the same group. The least mean percentage survival (40.3%) in the remaining three groups occurred in the cross of female hybrid (right pectoral fin absent) × male C. gariepinus (right pectoral fin absent). A maximum of nine types of aberrations was observed in the four mating groups , double dorsal fin, curved posterior dorsal fin, spineless right pectoral fin, right pectoral fin absent, left pectoral fin absent, rudimentary pectoral fin, both pectoral fins absent, double anal fin and curved anterior dorsal fin. These nine aberration types were recorded in the Clarias×,Clarias group, with a total frequency ranging from 7.14% to 75.00%. The least number of aberrations was observed in the hybrid ×Clarias group (double dorsal fin and both pectoral fins absent) with a frequency range of 1.47,5.55%. No aberration was observed in two crosses involving female hybrid (right or left pectoral fin absent) × female C. gariepinus (normal). The level of aberrations in some of these crosses indicates the involvement of genotype rather than the influence of environment. [source] A New Perleidiform (Actinopterygii, Osteichthyes) from the Middle Anisian (Middle Triassic) of Yunnan, South ChinaACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 3 2009Zuoyu SUN Abstract: Two complete specimens from the Pelsonian (Middle Anisian, Middle Triassic) of Luoping, Yunnan Province, South China are referred to a new actinopterygian genus, Luopingichthys gen. nov., and ascribed to the perleidiform family Polzbergidae based especially on a typical synapomorphy of a peculiar premaxillary-maxillary complex, i.e., the fusion between premaxillary and maxillary along the antero-dorsal margin of the maxillary. The new taxon differs from other deep-bodied representatives of the family, Felberia and Stoppania, in its fusiform or deep fusiform body shape; sickle-shaped preopercular with short infraorbital process; lack of modified scales at the base of the anal fin; the short-based dorsal fin; scarcely ornamented scales; and thin anterior teeth. Based on a redescription of the holotype of the taxon Ctenognathichthys hattichi from the Middle Triassic (Ladinian) Prosanto Formation, Canton Graubünden, eastern Switzerland, the only known specimen, which shows the same fusion between premaxillary and maxillary, the systematic position of the species is clarified and the taxon is proposed to be a further representative of the family Polzbergidae, and is transferred to the new genus. [source] A new articulated hybodontoid from Late Permian of northwestern ChinaACTA ZOOLOGICA, Issue 2009N.-Z. Wang Abstract A new genus and species of hybodontoid elasmobranchs, Gansuselache tungshengi, is described on the basis of an articulated skeleton from the Fangshankou Formation (Late Permian) of the Mazongshan Mountain of Gansu Province, northwestern China. All dermal skeletons including dorsal fin-spines, cephalic spines, dermal denticles and one tooth are well preserved in their natural position. It is a shark of about 490 mm total length with a fusiform body. The braincase has large, downturned postorbital processes and otic capsules, no postorbital articulation, long palatoquadrate and large triangular Meckel's cartilage. It bears two dorsal fins and two pairs of heteromorphic cephalic spines. The tooth is of low-crowned, multicuspid type; the elongate tooth crown has stout crown shoulder and well-developed, rounded labial peg; the cusp and cusplets are moderately tumid, and have a few strong and curved folds; the tooth root is higher on the labial face than the lingual face. The dermal denticle is placoid scale-like, with its crown surface ornamented with some parallel ridges. Gansuselache, the first articulated hybodontiform from Asia, also represents the first complete hybodontiform from the Permian. [source] A juvenile Early Carboniferous (Viséan) coelacanth from Rösenbeck (Rhenish Mountains, Germany) with derived postcranial charactersFOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 2 2010Florian Witzmann Abstract A small coelacanth specimen of Viséan age from a newly described locality near Rösenbeck at the northern margin of the Rhenish Mountains (North Rhine-Westphalia, Germany) is described. The head and pectoral girdle are not preserved, however, the specimen can be distinguished from all other known Carboniferous coelacanths by derived characters of the articulated postcranial skeleton. Derived characters include: (1) The slender first and second dorsal fins that carry only seven to eight and six fin rays, respectively. (2) Both the pelvic and anal fin have a broad base and are unusually weakly lobed. (3) The fin rays of the second dorsal fin are much more robust than those of the first dorsal fin. (4) The second dorsal and anal fins are longer than the first dorsal and pelvic fins. The Rösenbeck coelacanth is interpreted as a juvenile specimen, since the basal plates that support the fins are not ossified. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of temperature and salinity on the settlement and survival of copepodids of Lepeophtheirus salmonis (Krøyer, 1837) on Atlantic salmon, Salmo salar L.JOURNAL OF FISH DISEASES, Issue 5 2000C S Tucker The effects of temperature and salinity on the settlement, subsequent survival and development of the copepodids of Lepeophtheirus salmonis on Atlantic salmon were investigated experimentally. There was a significantly greater settlement and survival of copepodids at 10 days post-infection (dpi) at 12 °C compared with at 7 °C at a constant salinity of 34,. Development of L. salmonis was also more rapid at 12 °C. Settlement was significantly greater at a salinity of 34, than at 24,. In one experiment, survival at 10 dpi was significantly greater at 34,; however, a second experiment found that there was no significant difference between the two saline levels. This may have been because of a rise in water temperature for 2 dpi, which appears to have overridden the effect of low salinity. Development of L. salmonis was more rapid at 34,. Copepodids settled on all of the external surfaces of the salmon, although the proportion on different surfaces varied between experiments. The gills, particularly at low temperatures, the body surface, and the pectoral and dorsal fins were especially favoured. [source] Effect of Light Intensity on Color Performance of False Clownfish, Amphiprion ocellaris CuvierJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2009Inayah Yasir Color performance of false clownfish, Amphiprion ocellaris Cuvier, was examined under three levels of light intensity (20,50 , 600,850 , and 2700,3500 lx) for 5 wk. The experiment was conducted in nine rectangular glass aquaria (25 × 25 × 20 cm) with three replicates. Each aquarium was stocked with 36 fish, and 3 fish were randomly sampled from each aquarium every other week. Digital images were taken weekly on each individual fish after it was anesthetized in MS-222. The color performance in hue, saturation, and brightness was quantified using image analysis. In addition to the whole-body analysis, each fish image was divided into ventral and dorsal parts to assess the body position-dependent effect. Furthermore, color differences between dorsal fin, anal fin, ventral fin, and caudal fin were also quantified. The whole body was brighter at low light than at medium or at high light intensity. Irrespective of light intensity, the dorsal side was more orange but less bright than the ventral side. Brighter light strengthened overall orange color on fish fins. The dorsal fin and ventral fins appeared more orange than the anal and caudal fins regardless of light intensity and exposure duration. Similar to body color, low light also led to brighter fins, especially for caudal and dorsal fins. Our results indicate that ambient light could regulate fish color performance but could not change the pigment dominance by ,-carotene. Light intensity is unlikely to change the contrast between dorsal and ventral sides, but dim light tends to make fish body brighter, and bright light strengthens orange color on fins. [source] Sharksucker,shark interaction in two carcharhinid speciesMARINE ECOLOGY, Issue 1 2006Juerg M. Brunnschweiler Abstract It is not known whether sharksuckers have positive or negative effects on their hosts, partly because this association is difficult to study in free-ranging fish. I observed the behaviour of sharks with and without sharksuckers, to determine whether the hosts actively avoid sharksuckers. Wild blacktip sharks, Carcharhinus limbatus, took evasive actions when sharksuckers, Echeneis naucrates, attached to them, presumably to escape from skin irritation or hydrodynamical drag caused by the sharksuckers. Sharksuckers were most often attached to the belly or back of the shark, and sharks reacted most strongly to sharksuckers on their heads, sides, and dorsal fins. Observations of two captive bull sharks, Carcharhinus leucas, indicated that swimming speed increased when sharksuckers were attached. This paper supports the hypothesis that sharksucker attachment irritates sharks, and that the relationship between the two is best viewed as a subtle host,parasite interaction. [source] ABUNDANCE OF BOTTLENOSE DOLPHINS IN THE BAYS, SOUNDS, AND ESTUARIES OF NORTH CAROLINAMARINE MAMMAL SCIENCE, Issue 1 2003Andrew J. Read We conducted a mark-recapture survey of bottlenose dolphins Tursiops truncatus in the bays, sounds, and estuaries of North Carolina during July 2000, using photographic identification techniques. During this survey we took 7,682 photographs of dolphins and, of these, 3,457 images were of sufficient quality for analysis. We identified 306 dolphins from distinctive nicks and notches on their dorsal fins. Eighry-six dolphins were photographed on more than one occasion during the course of the survey; one dolphin was photographed on four separate days. We then applied the results of our photographic analyses to several mark-recapture models and examined potential violations of the assumptions of these models, including an unexpected correlation between photo quality and mark distinctiveness. Our analysis suggests that our results are robusr to possible violations of these assumptions. The resulting estimates were then scaled to account for the proportion (0.46) of unmarked dolphins in the population. Our best estimate of the number of dolphins present in the inshore waters of North Carolina during July 2000 is 1,033 with a 95% Confidence Interval of 860,1,266 (CV = 0.099). Most dolphins were found in the northern part of the study area, which includes the second largest estuarine system in the United States. [source] Comparing skeletal development of wild and hatchery-reared Senegalese sole (Solea senegalensis, Kaup 1858): evaluation in larval and postlarval stagesAQUACULTURE RESEARCH, Issue 14 2009Paulo Jorge Gavaia Abstract The Senegalese sole is a marine pleuronectiform that naturally occurs in Southern Europe and Mediterranean region where it is being produced in aquaculture, in particular in Portugal and Spain. The aim of this study was to assess the quality of hatchery-reared larvae in comparison with those reared in the wild, and determine to which extension wild growing larvae are also affected by skeletal deformities. The main structures affected included those forming the axial skeleton, the caudal fin complex and both anal and dorsal fins, with the most prevalent anomalies affecting caudal vertebrae and arches. Hatchery-reared fish presented a higher incidence of deformities (79%) compared with the 19% observed in wild specimens. In wild postlarvae collected in Autumn no deformities were observed. This work clearly shows that wild Senegalese sole present less skeletal deformities than those hatchery-reared during larval stages, indicating a selective mortality of wild deformed fish and/or an effect of aquaculture-related rearing conditions in the development of skeletal deformities in sole. [source] Dolphins in a bottle: abundance, residency patterns and conservation of bottlenose dolphins Tursiops truncatus in the semi-closed eutrophic Amvrakikos Gulf, GreeceAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2008Giovanni Bearzi Abstract 1.Boat surveys were conducted between 2002 and 2005 to study bottlenose dolphins living in the 400 km2 Amvrakikos Gulf, western Greece. During 116 survey days, 4705 km of total effort resulted in the individual photo-identification of 106 animals, through long-term natural markings on their dorsal fins. 2.Mark,recapture analyses based on the Mth model provided estimates of 82 marked individuals in 2003 (95% CI=80,91), 92 in 2004 (95% CI=86,108) and 98 in 2005 (95% CI=94,110). To include the unmarked portion of the population, the proportion of unmarked individuals was computed based on the number of photographs of marked and unmarked dorsal fins. The mean proportion of unmarked animals in the population was 0.338 (95% CI=0.288,0.389). By adding this to the estimate for marked animals in 2005, considered as the most robust, a total population estimate of 148 individuals (95% CI=132,180) was obtained. 3.Dolphin encounter rates in 2003,2005 did not show significant variations, and averaged 7.2 groups per 100 km or 72.5 individuals per 100 km. Encounter rates within the Gulf were about one order of magnitude greater than those found for bottlenose dolphins in nearby eastern Ionian Sea coastal waters. 4.Mean dolphin density in the Gulf was 0.37 animals km,2. This relatively high density, together with high levels of site fidelity shown by most individuals, was thought to be related primarily to prey availability, particularly of epipelagic schooling fish. 5.The importance of the semi-closed Amvrakikos Gulf for bottlenose dolphins and other threatened species encourages the adoption of measures aimed to conserve its valuable ecosystems and raise the naturalistic profile of the area, while promoting environment-conscious development. Meaningful action includes restoring natural hydrology (e.g. freshwater input from rivers), curtailing pollution from various sources, responsible fisheries and aquaculture management, and control of illegal fishing. Interactions between dolphins and fisheries also deserve careful quantitative investigation. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||