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Cetaceans
Kinds of Cetaceans Terms modified by Cetaceans Selected AbstractsDOES DIVING LIMIT BRAIN SIZE IN CETACEANS?MARINE MAMMAL SCIENCE, Issue 2 2006Lori Marino Abstract We test the longstanding hypothesis, known as the dive constraint hypothesis, that the oxygenation demands of diving pose a constraint on aquatic mammal brain size.Using a sample of 23 cetacean species we examine the relationship among six different measures of relative brain size, body size, and maximum diving duration. Unlike previous tests we include body size as a covariate and perform independent contrast analyses to control for phylogeny. We show that diving does not limit brain size in cetaceans and therefore provide no support for the dive constraint hypothesis. Instead, body size is the main predictor of maximum diving duration in cetaceans. Furthermore, our findings show that it is important to conduct robust tests of evolutionary hypotheses by employing a variety of measures of the dependent variable, in this case, relative brain size. [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] Neuroanatomy of the harbor porpoise (Phocoena phocoena) from magnetic resonance imagesJOURNAL OF MORPHOLOGY, Issue 3 2003Lori Marino Abstract Cetacean (dolphin, whale, and porpoise) brains are among the least-studied mammalian brains because of the formidability of collecting and histologically preparing such relatively rare and large specimens. Among cetaceans, there exist relatively few studies of the brain of the harbor porpoise (Phocoena phocoena). Magnetic resonance imaging (MRI) offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Therefore, MRI has become a critical tool in the study of the brain of cetaceans and other large species. This article represents the first MRI-based anatomically labeled three-dimensional description of the harbor porpoise brain. Coronal plane sections of the brain of a young harbor porpoise were originally acquired and used to produce virtual digital scans in the other two orthogonal spatial planes. A sequential set of images in all three planes has been anatomically labeled and displays the proportions and positions of major neuroanatomical features. These images allow for the visualizing of the distinctive features of the harbor porpoise brain from various orientations by preserving the gross morphological structure of the specimen. J. Morphol. 257:308,347, 2003. © 2003 Wiley-Liss, Inc. [source] Structure of the cerebral cortex of the humpback whale, Megaptera novaeangliae (Cetacea, Mysticeti, Balaenopteridae)THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2007Patrick R. Hof Abstract Cetaceans diverged from terrestrial mammals between 50 and 60 million years ago and acquired, during their adaptation to a fully aquatic milieu, many derived features, including echolocation (in odontocetes), remarkable auditory and communicative abilities, as well as a complex social organization. Whereas brain structure has been documented in detail in some odontocetes, few reports exist on its organization in mysticetes. We studied the cerebral cortex of the humpback whale (Megaptera novaeangliae) in comparison to another balaenopterid, the fin whale, and representative odontocetes. We observed several differences between Megaptera and odontocetes, such as a highly clustered organization of layer II over the occipital and inferotemporal neocortex, whereas such pattern is restricted to the ventral insula in odontocetes. A striking observation in Megaptera was the presence in layer V of the anterior cingulate, anterior insular, and frontopolar cortices of large spindle cells, similar in morphology and distribution to those described in hominids, suggesting a case of parallel evolution. They were also observed in the fin whale and the largest odontocetes, but not in species with smaller brains or body size. The hippocampal formation, unremarkable in odontocetes, is further diminutive in Megaptera, contrasting with terrestrial mammals. As in odontocetes, clear cytoarchitectural patterns exist in the neocortex of Megaptera, making it possible to define many cortical domains. These observations demonstrate that Megaptera differs from Odontoceti in certain aspects of cortical cytoarchitecture and may provide a neuromorphologic basis for functional and behavioral differences between the suborders as well as a reflection of their divergent evolution. Anat Rec, 290:1,31, 2007. © 2006 Wiley-Liss, Inc. [source] Two New Species of Symbiotic Ciliates from the Respiratory Tract of Cetaceans with Establishment of the New Genus Planilamina n. gen. (Dysteriida, Kyaroikeidae)THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2006HONGWEI MA ABSTRACT. Examination of mucus discharged from the blowhole of Atlantic bottlenose dolphin (Tursiops truncatus) at Marine Life Oceanarium, Gulfport, Mississippi, and false killer whale (Pseudorca crassidens) and Atlantic bottlenose dolphin at SeaWorld Orlando, Orlando, Florida, using live observations and protargol impregnation revealed mixed infections of Kyaroikeus cetarius and two new species. Planilamina n. gen. is characterized by a C-shaped argentophilic band located along the laterally flattened margin of cell and extending from the cell apex to subposterior cone-shaped podite; a deep oral cavity containing one short preoral kinety, two circumoral kineties, seven to 13 infundibular kineties, and a cytostome; a broadly funnel-shaped cytopharynx reinforced by argentophilic fibers but without nematodesmata; closely packed postoral kinetofragments set in a pocket located anterior left of the podite; and somatic kineties as a right field closely situated at the right surface and a left field bordering the anterior left margin of the oral cavity. The type species for the genus, Planilamina ovata n. sp., is distinguished from its sister species Planilamina magna n. sp. by the following characteristics: body size (28,65 × 20,43 ,m vs. 57,90 × 40,63 ,m), number of right field kineties (38,55 vs. 79,99), and position of the anterior end of the leftmost kinety in the right somatic field (anterior one-third vs. mid-body). The morphogenesis of Planilamina ovata is similar to that of K. cetarius. The diagnosis of Kyaroikeidae is emended to accommodate the new genus. [source] The Pelagos Sanctuary for Mediterranean marine mammalsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2008Giuseppe Notarbartolo-di-Sciara Abstract 1.In February 2002, France, Italy and Monaco agreed to establish an international sanctuary for Mediterranean marine mammals. The resulting Pelagos Sanctuary encompasses over 87500 km2 of the north-western Mediterranean Sea, extending between south-eastern France, Monaco, north-western Italy and northern Sardinia, and surrounding Corsica and the Tuscan Archipelago. 2.The Pelagos Sanctuary illustrates how the tenets of Marine Protected Area (MPA) design can be reconciled with the dynamic nature of oceanic systems, because its spatial scale was defined by oceanographic and ecological considerations, specifically the location of the Ligurian permanent frontal system. 3.By expanding protective measures beyond national waters, the Pelagos Sanctuary also sets a precedent for the implementation of pelagic protected areas in the high seas. The Pelagos Sanctuary will contribute to the conservation of the Mediterranean Sea at two scales: (i) locally, by protecting important cetacean foraging and breeding grounds in the Ligurian Sea, and by providing ,umbrella' protection to other marine predators in this area; and (ii) regionally, by empowering other conservation measures, such as the Specially Protected Areas Protocol of the Barcelona Convention and the wider goals of the Agreement on the Conservation of Cetaceans of the Black and Mediterranean Seas (ACCOBAMS). 4.However, because few cetacean species are resident within the Sanctuary, their effective long-term conservation will require large-scale management and coordinated monitoring throughout the Mediterranean basin. Copyright © 2007 John Wiley & Sons, Ltd. [source] Detecting the impact of oceano-climatic changes on marine ecosystems using a multivariate index: The case of the Bay of Biscay (North Atlantic-European Ocean)GLOBAL CHANGE BIOLOGY, Issue 1 2008GEORGES HEMERY Abstract Large-scale univariate climate indices (such as NAO) are thought to outperform local weather variables in the explanation of trends in animal numbers but are not always suitable to describe regional scale patterns. We advocate the use of a Multivariate Oceanic and Climatic index (MOCI), derived from ,synthetic' and independent variables from a linear combination of the total initial variables objectively obtained from Principal Component Analysis. We test the efficacy of the index using long-term data from marine animal populations. The study area is the southern half of the Bay of Biscay (43°,47°N; western Europe). Between 1974 and 2000 we monitored cetaceans and seabirds along 131000 standardized line transects from ships. Fish abundance was derived from commercial fishery landings. We used 44 initial variables describing the oceanic and atmospheric conditions and characterizing the four annual seasons in the Bay of Biscay. The first principal component of our MOCI is called the South Biscay Climate (SBC) index. The winter NAO index was correlated to this SBC index. Inter-annual fluctuations for most seabird, cetacean and fish populations were significant. Boreal species (e.g. gadiformes fish species, European storm petrel and Razorbill ,) with affinities to cold temperate waters declined significantly over time while two (Puffin and Killer Whale) totally disappeared from the area during the study period. Meridional species with affinities to hotter waters increased in population size. Those medium-term demographic trends may reveal a regime shift for this part of the Atlantic Ocean. Most of the specific observed trends were highly correlated to the SBC index and not to the NAO. Between 40% and 60% of temporal variations in species abundance were explained by the multivariate SBC index suggesting that the whole marine ecosystem is strongly affected by a limited number of physical parameters revealed by the multivariate SBC index. Aside the statistical error of the field measurements, the remaining variation unexplained by the physical characteristics of the environment correspond to the impact of anthropogenic activities such overfishing and oil-spills. [source] A review of cetacean occurrence in West African waters from the Gulf of Guinea to AngolaMAMMAL REVIEW, Issue 1 2010Caroline R. WEIR ABSTRACT 1The cetacean fauna of the west coast of Africa is poorly described. Therefore, literature on the occurrence of cetacean species in the waters of 13 potential West African range states from the Gulf of Guinea to Angola was reviewed, including sighting, stranding, capture, bycatch and whaling records. 2At least 28 species of cetacean were documented in the study region, comprising seven baleen whale species and 21 species of toothed whale (including at least 17 delphinid species). 3Cetaceans could be broadly split into seven ecological categories, based on their distribution. A warm temperate/tropical deep-water cetacean community dominated the study area. Cooler water from the Benguela Current influenced southern Angola (,16°S latitude) and at least three cetacean species occurred predominantly in this region. 4Only three or fewer species were confirmed in the waters of Togo, Nigeria, Cameroon and the Democratic Republic of Congo. Seventeen or more species were documented in Ghana, Gabon and Angola, where dedicated cetacean research projects have been initiated in recent years. Angola had the most diverse documented cetacean community: 28 confirmed species. 5The humpback whale Megaptera novaeangliae was the most widely recorded species, and was documented in 11 (85%) countries. Sperm whales Physeter macrocephalus, Bryde's whales Balaenoptera cf. brydei, bottlenose dolphins Tursiops truncatus and Atlantic spotted dolphins Stenella frontalis were recorded in over half of the countries. [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] FIELD EXPERIMENTS SHOW THAT ACOUSTIC PINGERS REDUCE MARINE MAMMAL BYCATCH IN THE CALIFORNIA DRIFT GILL NET FISHERYMARINE MAMMAL SCIENCE, Issue 2 2003Jay Barlow Abstract A controlled experiment was carried out in 1996,1997 to determine whether acoustic deterrent devices (pingers) reduce marine mammal bycatch in the California drift gill net fishery for swordfish and sharks. Using Fisher's exact test, bycatch rates with pingers were significantly less for all cetacean species combined (P < 0.001) and for all pinniped species combined (P= 0.003). For species tested separately with this test, bycatch reduction was statistically significant for short-beaked common dolphins (P= 0.001) and California sea lions (P= 0.02). Bycatch reduction is not statistically significant for the other species tested separately, but sample sizes and statistical power were low, and bycatch rates were lower in pingered nets for six of the eight other cetacean and pinniped species. A log-linear model relating the mean rate of entanglement to the number of pingers deployed was fit to the data for three groups: short-beaked common dolphins, other cetaceans, and pinnipeds. For a net with 40 pingers, the models predict approximately a 12-fold decrease in entanglement for short-beaked common dolphins, a 4-fold decrease for other cetaceans, and a 3-fold decrease for pinnipeds. No other variables were found that could explain this effect. The pinger experiment ended when regulations were enacted to make pingers mandatory in this fishery. [source] Tissue-specific distribution and whole-body burden estimates of persistent organic pollutants in the bottlenose dolphin (Tursiops truncatus)ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2010Jennifer E. Yordy Abstract Most exposure assessments for free-ranging cetaceans focus on contaminant concentrations measured in blubber, and few data are available for other tissues or the factors governing contaminant distribution among tissues. The goal of this study was to provide a detailed description of the distribution of persistent organic pollutants (POPs) within the common bottlenose dolphin (Tursiops truncatus) body and assess the role of lipid dynamics in mediating contaminant distribution. Thirteen tissues (brain, blubber, heart, liver, lung, kidney, mammary gland, melon, skeletal muscle, spleen, thyroid, thymus, and testis/uterus) were sampled during necropsy from bottlenose dolphins (n,=,4) and analyzed for lipid and 85 POPs, including polychlorinated biphenyls, organochlorine pesticides, and polybrominated diphenyl ethers. Significant correlations between tissue POP concentrations and lipid suggest that distribution of POPs is generally related to tissue lipid content. However, blubber:tissue partition coefficients ranged widely from 0.753 to 6.25, suggesting that contaminant distribution is not entirely lipid-dependent. Tissue-specific and whole-body contaminant burdens confirmed that blubber, the primary site of metabolic lipid storage, is also the primary site for POP accumulation, contributing >90% to the whole-body burdens. Observations also suggest that as lipid mobilizes from blubber, contaminants may redistribute, leading to elevated tissue concentrations. These results suggest that individuals with reduced blubber lipid may be at increased risk for exposure-related health effects. However, this study also provides evidence that the melon, a metabolically inert lipid-rich structure, may serve as an alternate depot for POPs, thus preventing the bulk of blubber contaminants from being directly available to other tissues. This unique physiological adaptation should be taken into consideration when assessing contaminant-related health effects in wild cetacean populations. Environ. Toxicol. Chem. 2010;29:1263,1273. © 2010 SETAC [source] Occurrence of several arsenic compounds in the liver of birds, cetaceans, pinnipeds, and sea turtlesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2003Reiji Kubota Abstract Concentrations of total arsenic and individual arsenic compounds were determined in livers of birds, cetaceans, pinnipeds, and sea turtles by using hydride generation-atomic absorption spectrometry and high-performance liquid chromatography/inductively coupled plasma-mass spectrometry. Hepatic arsenic concentrations in loggerhead turtles (11.2 ± 3.0 ,g/g dry wt) and black-footed albatrosses (12.2 ± 10.8 ,g/g dry wt) were extremely high among the species examined, and the values were comparable with those of lower trophic marine animals such as fishes, cephalopods, crustaceans, and shellfishes. In all the species, arsenobetaine was the predominant arsenic compound in the livers. Especially, for black-footed albatrosses and black-tailed gull, the mean percentage of arsenobetaine was as high as 97.1 and 87.5, respectively, of extractable arsenic. The present study is among the first on arsenic speciation in avian species. Total arsenic concentration was strongly correlated with the concentration of arsenobetaine, while no significant relationship was observed between total arsenic concentration and other arsenic compounds in these animals. Because arsenobetaine is known to be rapidly excreted into the urine in humans and experimental animals, the observed results suggest that higher trophic marine animals might have a unique metabolism of arsenobetaine and that arsenobetaine plays an important role in the accumulation of arsenic in these animals. [source] Polychlorinated biphenyls, organochlorine pesticides, tris(4-chlorophenyl)methane, and tris(4-chlorophenyl)methanol in livers of small cetaceans stranded along Florida coastal waters, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Mafumi Watanabe Abstract Concentrations of polychlorinated biphenyl congeners (PCBs) and organochlorine pesticides were determined in the livers of bottlenose dolphins, Atlantic spotted dolphins, and pygmy sperm whales found stranded along the coastal waters of Florida, USA, during 1989 to 1994. The PCBs were the most predominant contaminants followed in order by DDTs, chlordanes, tris(4-chlorophenyl)methane (TCPMe), tris(4-chlorophenyl)methanol (TCPMOH), hexachlorobenzene, and hexachlorocyclohexane isomers. Among the cetaceans analyzed, organochlorine concentrations were greatest in bottlenose dolphins followed by Atlantic spotted dolphins and pygmy sperm whales. Hexa- and heptachlorobiphenyls were the predominant PCB congeners found in the livers of dolphins. Patterns of relative concentrations of PCB congeners varied among individual bottlenose dolphins. A few individuals contained predominant concentrations of octa- (CB-199, 196/201) and nonachlorobiphenyl (CB-206, 208) congeners, which suggested exposure to the highly chlorinated PCB formulation, Aroclor® 1268, a contaminant at a coastal site in Georgia bordering northern Florida. The estimated 2,3,7,8-tetrachlorodibenzo- p -dioxin toxic equivalents (TEQs) of coplanar PCBs in bottlenose dolphins were 170 to 18,000 pg/g, lipid weight (mean: 5,400 pg/g) with mono- ortho congeners 118, 105, and 156 contributing more than 80% of the TEQs. The ratios of CB-169 to CB-126 in cetacean livers were linearly related to total PCB concentrations, which suggested a strong induction of microsomal monooxygenase enzymes in the liver. The hepatic concentrations of TCPMe and TCPMOH in bottlenose dolphins and Atlantic spotted dolphins were greater than those in the blubber of marine mammals of various regions, which suggested the presence of sources for these chemicals along the Atlantic coast of Florida. [source] Oxidative metabolic profiles of Brucella strains isolated from marine mammals: contribution to their species classificationFEMS MICROBIOLOGY LETTERS, Issue 2 2007Isabelle Jacques Abstract Since the 1990s, Brucella strains not matching the characteristics of any of the six conventional species have been isolated worldwide from marine mammals. In this study, 31 Brucella strains isolated from various marine mammals were examined for their oxidative metabolic pattern on 12 amino-acid and carbohydrate substrates. Three main oxidative profiles different from those of the Brucella terrestrial mammal strains were identified for the marine mammal strains: one gathering strains isolated from pinnipeds and two gathering strains from cetaceans. Thus, both oxidative metabolism results and previous molecular studies are in agreement with the proposal of two new Brucella species, Brucella pinnipediae and Brucella cetaceae, to classify the Brucella strains isolated from marine mammals, and are also in accordance with a classification of species of the Brucella genus based on host preference. [source] Flow-field observations of a tidally driven island wake used by marine mammals in the Bay of Fundy, CanadaFISHERIES OCEANOGRAPHY, Issue 5 2007D. W. JOHNSTON Abstract Correlations between fine-scale oceanographic features and aggregations of marine mammals are frequently reported, but the physical forces shaping these relationships are rarely explored. We conducted a series of oceanographic observations and remote sensing surveys of an oceanographic feature near Grand Manan Island known to attract marine mammals on flood tides. We tracked drift drogues from cliff-top with a theodolite and conducted box-type surveys with an acoustic Doppler current profiler (ADCP) to assess flow patterns within the oceanographic feature. The feature was also visualized with Synthetic Aperture Radar (SAR) scenes. Drift drogues were advected towards a shear line originating near the northern tip of the island and entrained in one or more eddies downstream. ADCP surveys confirmed the presence of the shear line between rapid easterly flow and slower return flow. As the tide progressed, the shear line extended and manifested a single anti-cyclonic eddy at its distal end. As the flood tide progressed, northerly flow along the eastern shore of the island intensified and deflected the shear line northwards, shedding the eddy at slack high water. SAR images confirmed the presence of the shearline and eddy system, illustrating the evolution of a wake behind the island on flood tides. Profiles of flow direction and acoustic backscatter revealed secondary flows within the wake consistent with models and observations of other wakes. Oceanographic and remote sensing observations confirm that an island wake is generated by tidal flow past Grand Manan Island and provide an ecological context for the predictable aggregations of odontocete and mysticete cetaceans observed foraging within this region. [source] Detecting the impact of oceano-climatic changes on marine ecosystems using a multivariate index: The case of the Bay of Biscay (North Atlantic-European Ocean)GLOBAL CHANGE BIOLOGY, Issue 1 2008GEORGES HEMERY Abstract Large-scale univariate climate indices (such as NAO) are thought to outperform local weather variables in the explanation of trends in animal numbers but are not always suitable to describe regional scale patterns. We advocate the use of a Multivariate Oceanic and Climatic index (MOCI), derived from ,synthetic' and independent variables from a linear combination of the total initial variables objectively obtained from Principal Component Analysis. We test the efficacy of the index using long-term data from marine animal populations. The study area is the southern half of the Bay of Biscay (43°,47°N; western Europe). Between 1974 and 2000 we monitored cetaceans and seabirds along 131000 standardized line transects from ships. Fish abundance was derived from commercial fishery landings. We used 44 initial variables describing the oceanic and atmospheric conditions and characterizing the four annual seasons in the Bay of Biscay. The first principal component of our MOCI is called the South Biscay Climate (SBC) index. The winter NAO index was correlated to this SBC index. Inter-annual fluctuations for most seabird, cetacean and fish populations were significant. Boreal species (e.g. gadiformes fish species, European storm petrel and Razorbill ,) with affinities to cold temperate waters declined significantly over time while two (Puffin and Killer Whale) totally disappeared from the area during the study period. Meridional species with affinities to hotter waters increased in population size. Those medium-term demographic trends may reveal a regime shift for this part of the Atlantic Ocean. Most of the specific observed trends were highly correlated to the SBC index and not to the NAO. Between 40% and 60% of temporal variations in species abundance were explained by the multivariate SBC index suggesting that the whole marine ecosystem is strongly affected by a limited number of physical parameters revealed by the multivariate SBC index. Aside the statistical error of the field measurements, the remaining variation unexplained by the physical characteristics of the environment correspond to the impact of anthropogenic activities such overfishing and oil-spills. [source] Perspectives on hyperphalangy: patterns and processesJOURNAL OF ANATOMY, Issue 3 2004Tim J. Fedak Abstract Hyperphalangy is a digit morphology in which increased numbers of phalanges are arranged linearly within a digit beyond the plesiomorphic condition. We analyse patterns and processes of hyperphalangy by considering previous definitions and occurrences of hyperphalangy among terrestrial and secondarily aquatic extant and fossil taxa (cetaceans, ichthyosaurs, plesiosaurs and mosasaurs), and recent studies that elucidate the factors involved in terrestrial autopod joint induction. Extreme hyperphalangy, defined as exceeding a threshold condition of 4/6/6/6/6, is shown only to be found among secondarily aquatic vertebrates with a flipper limb morphology. Based on this definition, hyperphalangy occurs exclusively in digits II and III among extant cetaceans. Previous reports of cetacean embryos having more phalanges than adults is clarified and shown to be based on cartilaginous elements not ossified phalanges. Developmental prerequisites for hyperphalangy include lack of cell death in interdigital mesoderm (producing a flipper limb) and maintenance of a secondary apical ectodermal ridge (AER), which initiates digit elongation and extra joint patterning. Factors of the limb-patterning pathways located in the interdigital mesoderm, including bone morphogenetic proteins (BMPs), BMP antagonists, fibroblast growth factors (FGFs), growth/differentiation factor-5 (GDF-5), Wnt-14 and ck-erg, are implicated in maintenance of the flipper limb, secondary AER formation, digit elongation and additional joint induction leading to hyperphalangy. [source] Observations on the biology and ecology of the blue shark in the North-east AtlanticJOURNAL OF FISH BIOLOGY, Issue 5 2001A. C. Henderson Of 159 blue sharks Prionace glauca examined (59% female, 41% male) from oceanic waters SW of Britain and Ireland, all but two males were immature. Size-at-age and growth rate were similar to previous studies in the North Atlantic, while stomach contents included cephalopods, fish, cetaceans, and to a lesser degree, birds and crustaceans. [source] Head morphology in perinatal dolphins: A window into phylogeny and ontogenyJOURNAL OF MORPHOLOGY, Issue 11 2006Michael A. Rauschmann Abstract In this paper on the ontogenesis and evolutionary biology of odontocete cetaceans (toothed whales), we investigate the head morphology of three perinatal pantropical spotted dolphins (Stenella attenuata) with the following methods: computer-assisted tomography, magnetic resonance imaging, conventional X-ray imaging, cryo-sectioning as well as gross dissection. Comparison of these anatomical methods reveals that for a complete structural analysis, a combination of modern imaging techniques and conventional morphological methods is needed. In addition to the perinatal dolphins, we include series of microslides of fetal odontocetes (S. attenuata, common dolphin Delphinus delphis, narwhal Monodon monoceros). In contrast to other mammals, newborn cetaceans represent an extremely precocial state of development correlated to the fact that they have to swim and surface immediately after birth. Accordingly, the morphology of the perinatal dolphin head is very similar to that of the adult. Comparison with early fetal stages of dolphins shows that the ontogenetic change from the general mammalian bauplan to cetacean organization was characterized by profound morphological transformations of the relevant organ systems and roughly seems to parallel the phylogenetic transition from terrestrial ancestors to modern odontocetes. J. Morphol., 2006. © 2006 Wiley-Liss, Inc. [source] Sperm head morphology in 36 species of artiodactylans, perissodactylans, and cetaceans (Mammalia)JOURNAL OF MORPHOLOGY, Issue 2 2005Amy Downing Meisner Abstract Detailed descriptions of mammalian sperm morphology across a range of closely related taxa are rare. Most contributions have been generalized descriptions of a few distantly related mammalian species. These studies have emphasized a generalized ungulate sperm morphology, but have not underscored several important morphological differences in ungulate sperm, such as head shape. The present study is the first to document descriptions of sperm head morphology using cold field-emission scanning electron microscopy (FE-SEM) for a large number of closely related mammalian species. In total, the sperm of 36 species in three orders: Artiodactyla (even-toed ungulates), Cetacea (whales, porpoises, and dolphins), and Perissodactyla (odd-toed ungulates) were examined to gather new information relevant to the debate about the phylogenetic placement of cetaceans relative to terrestrial ungulates. In all species examined, the sperm heads were generally flattened and ovate in shape with a distinct apical ridge, although considerable variation in sperm head shape was detected, both within and between orders. In artiodactylans, the sperm head was uniformly flat in lateral view, whereas perissodactylan and cetacean sperm heads showed a distinct posterior thickening. In both artiodactylans and perissodactylans, the mitochondria were elongate and wound in a tight helix around the midpiece, whereas in cetaceans the mitochondria were rounded and appeared to be randomly arranged around the midpiece. Additionally, prominent ridges running along the anterior,posterior axis were observed in the postacrosomal region of the sperm head in four species of cetaceans. These ridges were not observed in any of the terrestrial ungulates examined. Pits or fenestrations were detected in the postacrosomal region in most artiodactylan species examined; these structures were not detected in perissodactylans or cetaceans. The equatorial segment of the acrosome was detected in the artiodactylan species examined, tentatively identified in perissodactylans, but not found in cetaceans. Its shape and location are described for relevant taxa. The presence of a recently reported substructure within the equatorial segment (the equatorial subsegment; Ellis et al. [2002] J Struct Biol 138:187,198) was detected in artiodactylans, and its shape is described for the species examined. © 2004 Wiley-Liss, Inc. [source] Neuroanatomy of the harbor porpoise (Phocoena phocoena) from magnetic resonance imagesJOURNAL OF MORPHOLOGY, Issue 3 2003Lori Marino Abstract Cetacean (dolphin, whale, and porpoise) brains are among the least-studied mammalian brains because of the formidability of collecting and histologically preparing such relatively rare and large specimens. Among cetaceans, there exist relatively few studies of the brain of the harbor porpoise (Phocoena phocoena). Magnetic resonance imaging (MRI) offers a means of observing the internal structure of the brain when traditional histological procedures are not practical. Therefore, MRI has become a critical tool in the study of the brain of cetaceans and other large species. This article represents the first MRI-based anatomically labeled three-dimensional description of the harbor porpoise brain. Coronal plane sections of the brain of a young harbor porpoise were originally acquired and used to produce virtual digital scans in the other two orthogonal spatial planes. A sequential set of images in all three planes has been anatomically labeled and displays the proportions and positions of major neuroanatomical features. These images allow for the visualizing of the distinctive features of the harbor porpoise brain from various orientations by preserving the gross morphological structure of the specimen. J. Morphol. 257:308,347, 2003. © 2003 Wiley-Liss, Inc. [source] Biogeography of common dolphins (genus Delphinus) in the Southwestern Atlantic OceanMAMMAL REVIEW, Issue 1 2010Maurício TAVARES ABSTRACT 1The common dolphins (genus Delphinus) have one of most problematic taxonomies and complex distribution patterns of all cetaceans. Although the taxonomy and the distribution seem to have been clarified somewhat in the eastern North Pacific and Indo-Pacific Oceans, many questions remain in the Southwestern Atlantic Ocean (SWA). We review the biogeography of Delphinus in the SWA. 2We reviewed data from strandings, incidental catches and sightings since 1922. Systematic surveys were conducted in five major areas. Twenty-one natural history collections were examined, and 135 skulls were measured. 3A total of 184 records of common dolphins were compiled. Delphinus apparently occurs in three stocks in the SWA: one located in northern Brazil and two from southeastern Brazil (,22°S) to central Argentina (,42°S). Two distinct patterns in habitat use were observed by depth: in southeastern Brazil, sightings were restricted to coastal waters with water depths ranging from 18m to 70m. On the other hand, in the area that extends from southern Brazil to Central Argentina (from 28°S to 42°S), sightings were recorded in deeper waters, ranging from 71m to 1435m, with the exception of occasional coastal sightings. The cranial analyses demonstrated that both short-beaked common dolphins Delphinus delphis and long-beaked common dolphins Dephinus capensis occur in the SWA. 4In the SWA, Delphinus seems to occur near areas of high productivity. One stock is associated with the productive waters discharged by the Amazon River and possibily with the coastal upwelling system off the coast of Venezuela, while the other stocks are associated with the Cabo Frio upwelling system and the Subtropical Convergence. Our results indicate that the current taxonomy does not adequately reflect the amount of variation within the genus in the world. [source] Ecology and conservation of common bottlenose dolphins Tursiops truncatus in the Mediterranean SeaMAMMAL REVIEW, Issue 2 2009GIOVANNI BEARZI ABSTRACT 1Bottlenose dolphins Tursiops truncatus are amongst the best-known cetaceans. In the Mediterranean Sea, however, modern field studies of cetaceans did not start until the late 1980s. Bottlenose dolphins have been studied only in relatively small portions of the basin, and wide areas remain largely unexplored. 2This paper reviews the ecology, behaviour, interactions with fisheries and conservation status of Mediterranean bottlenose dolphins, and identifies threats likely to have affected them in historical and recent times. 3Whilst intentional killing was probably the most important cause of mortality until the 1960s, important ongoing threats include incidental mortality in fishing gear and the reduced availability of key prey caused by overfishing and environmental degradation throughout the region. Additional potential or likely threats include the toxic effects of xenobiotic chemicals, epizootic outbreaks, direct disturbance from boating and shipping, noise, and the consequences of climate change. 4The flexible social organization and opportunistic diet and behaviour of bottlenose dolphins may allow them to withstand at least some of the effects of overfishing and habitat degradation. However, dolphin abundance is thought to have declined considerably in the region and management measures are needed to prevent further decline. 5Management strategies that could benefit bottlenose dolphins, such as sustainable fishing, curbing marine pollution and protecting biodiversity, are already embedded in legislation and treaties. Compliance with those existing commitments and obligations should be given high priority. [source] Design and field methods for sighting surveys of cetaceans in coastal and riverine habitatsMAMMAL REVIEW, Issue 1 2008STEVE DAWSON ABSTRACT 1Dolphins and porpoises in coastal and/or riverine habitats face serious conservation threats, yet surveys of their abundance are often especially difficult due to the challenges imposed by the habitats. Because many of these species occur in developing countries, lack of resources imposes a further set of challenges. 2We offer advice on designing and conducting line-transect surveys with a focus on sound, practical, design rather than analytical sophistication, and we attempt, where possible, to offer simple, inexpensive solutions. 3We guide the reader through the questions of what kind of survey should be done, whether by boat or aircraft, and we discuss ways to avoid bias and increase precision. 4Our treatment of field methods focuses especially on robust, but low-cost, approaches. We provide two case studies to illustrate the implementation of these ideas. [source] Mixed species groups in mammalsMAMMAL REVIEW, Issue 3-4 2003EVA STENSLAND ABSTRACT 1.,Mixed species groups have long been noted in birds, but they also occur among different species of mammals ranging from closely related species to species from different orders. Mixed species groups of mammals occur in many different habitats, e.g. ungulates on the savannah, primates in various types of forests and cetaceans in the oceans. Mixed species groups are very different in their duration, frequency, predominant activity and structure depending on the species interacting and the habitat they occur in. 2.,Functional explanations for mixed species groups usually fall within two categories: foraging advantages and predator avoidance. However, there could also be other social and reproductive advantages of mixed species groups that could contribute to their formation and stability. The advantages do not have to be equally distributed between the participating species and can also vary according to season and the presence of predators. 3.,It is important that all investigators of mixed species groups take their studies one step further after the naturalistic description and test the function and benefits of mixed species groups in order to give more strength to their conclusions. In this paper we review and discuss the function of mixed species groups in mammals and suggest an approach on how to investigate the function of such groups. [source] Determining the sex of bottlenose dolphins from Doubtful Sound using dorsal fin photographsMARINE MAMMAL SCIENCE, Issue 1 2009Lucy E. Rowe Abstract Sexing cetaceans usually requires time-consuming observation, or genetic sexing via biopsy sampling or skin swabbing. We developed a method to determine the sex of bottlenose dolphins (Tursiops sp.) in Doubtful Sound, Fiordland, using laser-metric dorsal fin photographs. From dorsal fin photographs of 43 bottlenose dolphins of known sex (25 females, 18 males) we analyzed the shape, proportion of fin area covered in scarring and epidermal lesions, and the number of fin nicks. Males had significantly higher rates of scarring (P < 0.001) and dorsal fin nicks (P < 0.01) than females, whereas the severity of epidermal lesions was higher in females (P < 0.05). A logistic regression applied to all measured variables, and measurements of dorsal fin size, indicated that the proportion of dorsal fin scarring (P < 0.001), number of fin nicks (P < 0.01), and dorsal fin surface area (P < 0.01) were significant variables and together correctly predicted the sex of 93% (40/43) of the dolphins. The classification function may not be applicable to other populations due to geographic variation in bottlenose dolphin morphology and social structure. The method is quick and noninvasive to apply, and further increases the value of dorsal fin photo-identification pictures. [source] Circadian and seasonal rhythms in the behavior of spinner dolphins (Stenella longirostris)MARINE MAMMAL SCIENCE, Issue 1 2009Flávio José de Lima Silva Abstract The present study investigated both circadian and seasonal fluctuations in the daytime activities of the spinner dolphin, Stenella longirostris, from the Fernando de Noronha Archipelago in Brazil. The number of dolphins, and aerial, and reproductive activities were documented. The observations were carried out from January 1997 to December 2001. Temporal series and rhythmic characteristics (mesor, rhythmic percentage, and acrophase) were obtained by COSINOR analysis and later compared. The dolphins entered the bay in the morning, displayed aerial and reproductive activities during daytime, and left the bay in late afternoon to the open ocean. This study indicated that the rainy season affected the three behaviors investigated decreasing the rhythms parameter and advancing the beginning of these activities. The number of individuals was higher during the dry season and the animals stayed longer inside the bay. During the dry season, there was a bimodal expression of aerial activity, expressing a longer use of the temporal niche than in the rainy season. The phases with high frequencies of aerial activity seemed associated with those showing high reproductive activity, both with peak frequencies at about 0800. The results represent an important contribution to the advancement of chronobiological studies, and to the biology of cetaceans, considering that the existence of circadian and seasonal rhythms was proven in the behavior of spinner dolphins in an area of the SW Atlantic. Moreover, it allows restricting periods of the day for the activities of tourism as a form of minimizing the impacts of the boats on the dolphins. [source] Consequences of injuries on survival and reproduction of common bottlenose dolphins (Tursiops truncatus) along the west coast of FloridaMARINE MAMMAL SCIENCE, Issue 4 2008Randall S. Wells Abstract Accurate identification of human-induced injuries that lead to death or interfere with reproduction is important for marine mammal management, as deaths exceeding established limits can lead to restrictions on fisheries or vessel operations. The fates of cetaceans last seen swimming with attached gear, particularly in pelagic fisheries, or with vessel strike lacerations, have been difficult to predict. Survival and reproduction data from long-term research on resident common bottlenose dolphins near Sarasota, Florida were examined relative to consequences of fishing gear ingestion, line entanglements, vessel strikes, and amputations of unknown origins. Fishing hooks embedded in the throat, goosebeak, or esophagus, or line wrapped around the goosebeak, generally lead to death. Multiple, constrictive line wraps around fin insertions can lead to amputation, blood loss, impaired mobility, or infection. Dolphins with ingested gear or severe entanglements may swim away with the gear, but likely die later. Propeller injuries involving only soft tissue were often survivable. Some dolphins survived amputations of the distal ends of fins, and continued to reproduce. As a precautionary approach, dolphins with ingested gear or severe constrictive entanglements should be considered mortalities, but extrapolations of findings from coastal bottlenose dolphins to other cetaceans and different gear must be done with caution. [source] DOES DIVING LIMIT BRAIN SIZE IN CETACEANS?MARINE MAMMAL SCIENCE, Issue 2 2006Lori Marino Abstract We test the longstanding hypothesis, known as the dive constraint hypothesis, that the oxygenation demands of diving pose a constraint on aquatic mammal brain size.Using a sample of 23 cetacean species we examine the relationship among six different measures of relative brain size, body size, and maximum diving duration. Unlike previous tests we include body size as a covariate and perform independent contrast analyses to control for phylogeny. We show that diving does not limit brain size in cetaceans and therefore provide no support for the dive constraint hypothesis. Instead, body size is the main predictor of maximum diving duration in cetaceans. Furthermore, our findings show that it is important to conduct robust tests of evolutionary hypotheses by employing a variety of measures of the dependent variable, in this case, relative brain size. [source] SEXUAL DIMORPHISM AND BODY SCARRING IN THE BOTO (AMAZON RIVER DOLPHIN) INIA GEOFFRENSISMARINE MAMMAL SCIENCE, Issue 1 2006A. R. Martin Abstract Measurements and quantitative descriptions of a large sample of live adult botos (Inia geoffrensis) were obtained from the Mamirauá Reserve in the central Amazon. Males were on average 16% longer and weighed 55% more than females, demonstrating that this species is one of the most sexually dimorphic of all cetaceans for size. Males were also pinker than females, more heavily scarred by intraspecific tooth rakes, and had more life-threatening injuries. Some larger males had areas of modified skin that may simply be scar tissue, but may also be a heritable characteristic used as a shield or weapon. As in sperm whales, sexual size dimorphism and male-male aggression appear to be linked in botos, suggesting fierce competition for a resource,probably mating opportunities. The boto is unique among river dolphins in that males are larger than females. This distinction implies long evolutionary separation and fundamental differences in social behavior. [source] | ||||||||||||||||||||||||||||