Enoshima Aquarium

Fujisawa, Japan

Enoshima Aquarium

Fujisawa, Japan
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Uyeno D.,Kagoshima University | Senou H.,Kanagawa Prefectural Museum of Natural History | Sakiyama T.,Enoshima Aquarium
Species Diversity | Year: 2016

A rare copepod parasitic on marine fish, Luetkenia elongata Shiino, 1963 (Siphonostomatoida: Pandaridae), is redescribed based on type specimens and additional specimens obtained from Luvarus imperialis Rafinesque, 1810 caught in the eastern and western North Pacific Ocean off California and Japan, respectively. This represents the first record of this parasite from Japanese waters. The copepod differs from its sole congener, L. Asterodermi Claus, 1864, by following features of the female: fourth pedigerous somite with one pair of elongate posterolateral lobes; genital complex bearing a pair of well-developed posterolateral lobes with one conical protuberance on lateral corner; abdomen clearly longer than wide; and caudal rami more than 2.0 times longer than wide. © 2016 The Japanese Society of Systematic Zoology.


Itoh T.,Enoshima Aquarium | Kakino W.,Kitasato University | Yoshida Y.,Tochigi Prefectural Fisheries Experimental Station
Japanese Journal of Limnology | Year: 2012

Seasonal flow patterns of the glochidia of the freshwater unionid mussel Inversiunio jokohamensis were investigated using a plankton net (5 × 20 cm frame, 0.113 mm mesh) in a paddy field ditch. Living glochidia were collected from February to May, being most abundant in February. Dead glochidium shells were collected from February to October, being most abundant in May. A few non-mature eggs were collected in March and May. Our study shows that a plankton net is useful to investigate the flow patterns and spawning seasons of the glochidia of I. jokohamensis. © 2012, The Japanese Society of Limnology. All rights reserved.


Toshino S.,Kitasato University | Miyake H.,Kitasato University | Ohtsuka S.,Hiroshima University | Okuizumi K.,Tsuruoka Kamo Aquarium | And 5 more authors.
Plankton and Benthos Research | Year: 2013

The giant cubozoan Morbakka virulenta was collected from the central part of the Seto Inland Sea, western Japan in October 2009, in order to observe its development and polyp formation. Fertilization occurred externally. Demersal fertilized eggs were obtained during the incubation of mature females and males kept at a temperature of ca. 17 to 21°C. From the two-cell stage onwards, fertilized eggs developed into blastulae within 4 h. The development of the blastulae stopped for 21 days after forming blastocysts. This formation of blastocysts is up to now unique within the Cnidaria. The planulae, which developed inside the cysts and lacked larval ocelli, this being characteristic for the Cubozoa, finally metamorphosed into polyps bearing only a single tentacle. The 16-tentacled-stage in polyps was reached about three months after this metamorphosis. Budding occurred in eight-tentacled polyps and swimming polyps were released nine days after the commencement of budding. These unique developmental features of M. virulenta may shed additional light on the evolution of life history strategies in the Cnidaria. © The Plankton Society of Japan.


Miyaji K.,Azabu University | Nagao K.,Ajinomoto Co. | Bannai M.,Ajinomoto Co. | Asakawa H.,Shimoda Floating Aquarium | And 7 more authors.
PLoS ONE | Year: 2010

From an evolutionary perspective, the ancestors of cetaceans first lived in terrestrial environments prior to adapting to aquatic environments. Whereas anatomical and morphological adaptations to aquatic environments have been well studied, few studies have focused on physiological changes. We focused on plasma amino acid concentrations (aminograms) since they show distinct patterns under various physiological conditions. Plasma and urine aminograms were obtained from bottlenose dolphins, pacific white-sided dolphins, Risso's dolphins, false-killer whales and C57BL/6J and ICR mice. Hierarchical cluster analyses were employed to uncover a multitude of amino acid relationships among different species, which can help us understand the complex interrelations comprising metabolic adaptations. The cetacean aminograms formed a cluster that was markedly distinguishable from the mouse cluster, indicating that cetaceans and terrestrial mammals have quite different metabolic machinery for amino acids. Levels of carnosine and 3-methylhistidine, both of which are antioxidants, were substantially higher in cetaceans. Urea was markedly elevated in cetaceans, whereas the level of urea cycle-related amino acids was lower. Because diving mammals must cope with high rates of reactive oxygen species generation due to alterations in apnea/reoxygenation and ischemia-reperfusion processes, high concentrations of antioxidative amino acids are advantageous. Moreover, shifting the set point of urea cycle may be an adaption used for body water conservation in the hyperosmotic sea water environment, because urea functions as a major blood osmolyte. Furthermore, since dolphins are kept in many aquariums for observation, the evaluation of these aminograms may provide useful diagnostic indices for the assessment of cetacean health in artificial environments in the future. © 2010 Miyaji et al.


Beedessee G.,Mauritius Oceanography Institute | Beedessee G.,Macquarie University | Watanabe H.,Japan Agency for Marine - Earth Science and Technology | Ogura T.,Japan Agency for Marine - Earth Science and Technology | And 8 more authors.
PLoS ONE | Year: 2013

Dispersal ability plays a key role in the maintenance of species in spatially and temporally discrete niches of deep-sea hydrothermal vent environments. On the basis of population genetic analyses in the eastern Pacific vent fields, dispersal of animals in the mid-oceanic ridge systems generally appears to be constrained by geographical barriers such as trenches, transform faults, and microplates. Four hydrothermal vent fields (the Kairei and Edmond fields near the Rodriguez Triple Junction, and the Dodo and Solitaire fields in the Central Indian Ridge) have been discovered in the mid-oceanic ridge system of the Indian Ocean. In the present study, we monitored the dispersal of four representative animals, Austinograea rodriguezensis, Rimicaris kairei, Alviniconcha and the scaly-foot gastropods, among these vent fields by using indirect methods, i.e., phylogenetic and population genetic analyses. For all four investigated species, we estimated potentially high connectivity, i.e., no genetic difference among the populations present in vent fields located several thousands of kilometers apart; however, the direction of migration appeared to differ among the species, probably because of different dispersal strategies. Comparison of the intermediate-spreading Central Indian Ridge with the fast-spreading East Pacific Rise and slow-spreading Mid-Atlantic Ridge revealed the presence of relatively high connectivity in the intermediate- and slow-spreading ridge systems. We propose that geological background, such as spreading rate which determines distance among vent fields, is related to the larval dispersal and population establishment of vent-endemic animal species, and may play an important role in controlling connectivity among populations within a biogeographical province. © 2013 Beedessee et al.


Nakagawa S.,Hokkaido University | Nakagawa S.,Japan Agency for Marine - Earth Science and Technology | Shimamura S.,Japan Agency for Marine - Earth Science and Technology | Takaki Y.,Japan Agency for Marine - Earth Science and Technology | And 15 more authors.
ISME Journal | Year: 2014

Deep-sea vents harbor dense populations of various animals that have their specific symbiotic bacteria. Scaly-foot gastropods, which are snails with mineralized scales covering the sides of its foot, have a gammaproteobacterial endosymbiont in their enlarged esophageal glands and diverse epibionts on the surface of their scales. In this study, we report the complete genome sequencing of gammaproteobacterial endosymbiont. The endosymbiont genome displays features consistent with ongoing genome reduction such as large proportions of pseudogenes and insertion elements. The genome encodes functions commonly found in deep-sea vent chemoautotrophs such as sulfur oxidation and carbon fixation. Stable carbon isotope (13 C)-labeling experiments confirmed the endosymbiont chemoautotrophy. The genome also includes an intact hydrogenase gene cluster that potentially has been horizontally transferred from phylogenetically distant bacteria. Notable findings include the presence and transcription of genes for flagellar assembly, through which proteins are potentially exported from bacterium to the host. Symbionts of snail individuals exhibited extreme genetic homogeneity, showing only two synonymous changes in 19 different genes (13 810 positions in total) determined for 32 individual gastropods collected from a single colony at one time. The extremely low genetic individuality in endosymbionts probably reflects that the stringent symbiont selection by host prevents the random genetic drift in the small population of horizontally transmitted symbiont. This study is the first complete genome analysis of gastropod endosymbiont and offers an opportunity to study genome evolution in a recently evolved endosymbiont. © 2014 International Society for Microbial Ecology All rights reserved.


Adachi A.,Enoshima Aquarium
Der Zoologische Garten | Year: 2016

Even today there is still a lot to learn regarding the biology of the diverse group of coelenterates. With a better knowledge the husbandry can be improved, too. Only since less than 40 years is it possible to keep and cultivate corals, and since almost 50 years some jellyfish species can be kept and bred successfully in an aquarium. But nevertheless it is still difficult to breed certain other jellyfish species for prolonged periods of time.The Enoshima Aquarium, which was opened in 1954, tried right from its beginning to be a pioneer amongst the Japanese aquariums for new husbandry and exhibition methods (Fig. 1). In the 1970s the Enoshima Aquarium became famous also outside of Japan for the trained fish shows (Gewalt, 1973). But already in 1973 the Enoshima Aquarium started to exhibit Moon jellyfish for the regular exhibition. Today 50 jellyfish species are shown in the exhibition. © 2015.


PubMed | Albion Fisheries Research Center, Mauritius Oceanography Institute, University of Tokyo, Enoshima Aquarium and 2 more.
Type: Journal Article | Journal: PloS one | Year: 2013

Dispersal ability plays a key role in the maintenance of species in spatially and temporally discrete niches of deep-sea hydrothermal vent environments. On the basis of population genetic analyses in the eastern Pacific vent fields, dispersal of animals in the mid-oceanic ridge systems generally appears to be constrained by geographical barriers such as trenches, transform faults, and microplates. Four hydrothermal vent fields (the Kairei and Edmond fields near the Rodriguez Triple Junction, and the Dodo and Solitaire fields in the Central Indian Ridge) have been discovered in the mid-oceanic ridge system of the Indian Ocean. In the present study, we monitored the dispersal of four representative animals, Austinograea rodriguezensis, Rimicaris kairei, Alviniconcha and the scaly-foot gastropods, among these vent fields by using indirect methods, i.e., phylogenetic and population genetic analyses. For all four investigated species, we estimated potentially high connectivity, i.e., no genetic difference among the populations present in vent fields located several thousands of kilometers apart; however, the direction of migration appeared to differ among the species, probably because of different dispersal strategies. Comparison of the intermediate-spreading Central Indian Ridge with the fast-spreading East Pacific Rise and slow-spreading Mid-Atlantic Ridge revealed the presence of relatively high connectivity in the intermediate- and slow-spreading ridge systems. We propose that geological background, such as spreading rate which determines distance among vent fields, is related to the larval dispersal and population establishment of vent-endemic animal species, and may play an important role in controlling connectivity among populations within a biogeographical province.


PubMed | Enoshima Aquarium, Japan Agency for Marine - Earth Science and Technology, University of Tokyo and Hokkaido University
Type: Journal Article | Journal: The ISME journal | Year: 2013

Deep-sea vents harbor dense populations of various animals that have their specific symbiotic bacteria. Scaly-foot gastropods, which are snails with mineralized scales covering the sides of its foot, have a gammaproteobacterial endosymbiont in their enlarged esophageal glands and diverse epibionts on the surface of their scales. In this study, we report the complete genome sequencing of gammaproteobacterial endosymbiont. The endosymbiont genome displays features consistent with ongoing genome reduction such as large proportions of pseudogenes and insertion elements. The genome encodes functions commonly found in deep-sea vent chemoautotrophs such as sulfur oxidation and carbon fixation. Stable carbon isotope ((13)C)-labeling experiments confirmed the endosymbiont chemoautotrophy. The genome also includes an intact hydrogenase gene cluster that potentially has been horizontally transferred from phylogenetically distant bacteria. Notable findings include the presence and transcription of genes for flagellar assembly, through which proteins are potentially exported from bacterium to the host. Symbionts of snail individuals exhibited extreme genetic homogeneity, showing only two synonymous changes in 19 different genes (13810 positions in total) determined for 32 individual gastropods collected from a single colony at one time. The extremely low genetic individuality in endosymbionts probably reflects that the stringent symbiont selection by host prevents the random genetic drift in the small population of horizontally transmitted symbiont. This study is the first complete genome analysis of gastropod endosymbiont and offers an opportunity to study genome evolution in a recently evolved endosymbiont.


PubMed | Enoshima Aquarium, Kitasato University, Kyoto University, University of Tokyo and Hokkaido University
Type: Journal Article | Journal: PloS one | Year: 2015

Brown adipose tissue (BAT) plays an important role in thermoregulation in species living in cold environments, given heat can be generated from its chemical energy reserves. Here we investigate the existence of BAT in blubber in four species of delphinoid cetacean, the Pacific white-sided and bottlenose dolphins, Lagenorhynchus obliquidens and Tursiops truncates, and Dalls and harbour porpoises, Phocoenoides dalli and Phocoena phocoena. Histology revealed adipocytes with small unilocular fat droplets and a large eosinophilic cytoplasm intermingled with connective tissue in the innermost layers of blubber. Chemistry revealed a brown adipocyte-specific mitochondrial protein, uncoupling protein 1 (UCP1), within these same adipocytes, but not those distributed elsewhere throughout the blubber. Western blot analysis of extracts from the inner blubber layer confirmed that the immunohistochemical positive reaction was specific to UCP1 and that this adipose tissue was BAT. To better understand the distribution of BAT throughout the entire cetacean body, cadavers were subjected to computed tomography (CT) scanning. Resulting imagery, coupled with histological corroboration of fine tissue structure, revealed adipocytes intermingled with connective tissue in the lowest layer of blubber were distributed within a thin, highly dense layer that extended the length of the body, with the exception of the rostrum, fin and fluke regions. As such, we describe BAT effectively enveloping the cetacean body. Our results suggest that delphinoid blubber could serve a role additional to those frequently attributed to it: simple insulation blanket, energy storage, hydrodynamic streamlining or contributor to positive buoyancy. We believe delphinoid BAT might also function like an electric blanket, enabling animals to frequent waters cooler than blubber as an insulator alone might otherwise allow an animal to withstand, or allow animals to maintain body temperature in cool waters during sustained periods of physical inactivity.

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