Japanese Journal of Ichthyology
Online ISSN : 1884-7374
Print ISSN : 0021-5090
ISSN-L : 0021-5090
Volume 16, Issue 2
Displaying 1-7 of 7 articles from this issue
  • Characteristics of the Digestive System in Larvae at the Stage of First Feeding
    Masaru Tanaka
    1969 Volume 16 Issue 2 Pages 41-49
    Published: September 15, 1969
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
    The digestive organs of 11 marine and9 freshwater teleost larvae were compared one another and with those of adults to speculate their function at the transitional stage (from prelarvae to postlarvae). The digestive tract of larvae is divided into two major types: the straight- and convolute-type. The former is seen in the fishes referred to clupeichthyes and mesoichthyes and the latter in the fishes of percichthyes.
    Generally, in parallel with the evolutional trend of fish, the digestive tract tends to become shorter with development of internal mucosal folds, external muscular coats and posterior valvular constriction . The taste buds are obscure and few in number in many marine fish larvae, but, they are well developed in freshwater fish larvae, especially in those having pharyngeal teeth at the prelarval stage. These rules are also applicable to the case of mucous cells in the pharynx and esophagus which produce PAS-positive materials at the present stage.
    The larvae whose adults have true stomach possess a shorter and slightly distending part between the esophagus and intestine. This is the early appearance of the stomach without gastric gland and blind sac. No differentiated pyloric caeca are seen, except in Salmo gairdnerii. In spite of some exceptions, intestinal epithelium is exclusively composed of columnar absorptive cells, provided with well developed striated border. Goblet cells, if exist, are extremly few. Glycogen and fat scarcely ac-cumulate in the liver. The pancreatic tissues with eosinophile zymogen granules form the compact organs in all species examined, and hepatopancreas is not yet formed even in those having this peculiar structure in the adults. The fact that basic structure of digestive system in larvae at the stage of first feeding is common with that of stomachless fish suggests the similarity between them in function.
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  • Akira Ochiai, Susumu Umeda
    1969 Volume 16 Issue 2 Pages 50-54
    Published: September 15, 1969
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
    The mature grey mullet, usually called “Karasumu-bora”, were examined based on the materials taken from the coastal water of Kochi Prefecture, Pacific coast, Shikoku Island, Japan.There is a tendency that the size of mature female is larger than ripe male;the former measuring 32 to 56 cm in standard length and the latter 27 to 42 cm. The ovarian eggs grow larger gradually from September to early October, when the eggs are small measuring less than 0.04 mm n in diameter, but they grow faster thence up to early November, when they gain the diameter of about 0.7 mm.The spent females are found only in the first decade of November in the area surveyed, while, the ripe males occur during the middle of October and early November.Various evidence thus accumulated will suggest the spawning of the grey mullet, Mugil cephalus taking place from late October to early November in the coastal water of Kochi Prefecture.
    (Department of Cultural Fisheries, Faculty of Agriculture, Kochi University Nangoku City, Kochi Prefecture, Japan)
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  • Nobuhiko Taniguchi
    1969 Volume 16 Issue 2 Pages 55-67
    Published: September 15, 1969
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
    Based on the characters of the neurocranium, 16 species of the sciaenid fishes are classified into Megalonibea-, Nibea-, Johnius-, Argyrosomus- and Pseudosciaena-forms.The Megalonibea-form comprises the genera Megalonibea, Miichthys and some species of Nibea;the Nibea-form the remain-ing species in the genus Nibea;the Johnius-form the genera Johnius and Wak;the Argyrosomus-form the genera Argyrosomus and Atrobucca;the Pseudosciaena-form the genera Pseudosciaena and Collichthys.Of these five forms, the Megalonibea- and Nibea-form are probably the most gene- ralized, and the Pseudosciaena- and Johnius-form specialized.The Argyrosomus-form is considered to be intermediate between the Nibea-form and Pseudosciaena-form.The neurocranium is proved to be an important character as well as the sagitta for the speculation of phylogeny of the sciaenid fishes.
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  • Isao Hayashi
    1969 Volume 16 Issue 2 Pages 68-73
    Published: September 15, 1969
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
    The microscopical structure of the reproductive ducts of L.japonicus has been studied.Both spermiduct and oviduct of the fish are single, short organs, and are characterized by the folded condition of tunica propria lined with a single epithelial cell layer mainly consisting of cuboidal or squamous cells.No cyclic changes of the epithelium and the tunica propria have been observed except that the vessels in the tunica propria became filled with blood at the spawning time and that the partial stratification of epithelial cell layer was found in the spermiduct of mature male collected in early January.Judging from the histological features, the duct seems to serve mainly as a pathway of gametes from the gonad to the extremity.It was also believed that the spermiduct may play a certain role in a degenerating process of the remaining spermatozoa in the duct.The oviduct is closed in the immature females as well as in the adult females in the months intervened between the spawning seasons, as observed in some other teleosts.The orifice is produced between the anus and the urinary orifice just prior to ovulation.
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  • Ryoichi Arai
    1969 Volume 16 Issue 2 Pages 74-77
    Published: September 15, 1969
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
    Four brotulid fish referred to the genus Bythites, one collected from Suruga Bay and the others from Tosa Bay, were examined.All these specimens are distinguished from Bythites lepidogenys Smith and Radcliffe by the arrangement of its lateral lines, number of the pectoral fin-rays and width of the interorbital space.Bythites matsubarai sp.nov.is proposed for the fish in the waters of Japan.
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  • Fuiio Yasuda, Naoki Oda, Seiichi Watanabe, Kenya Mizuguchi
    1969 Volume 16 Issue 2 Pages 78-82
    Published: September 15, 1969
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
  • Clifford Ray Johnson
    1969 Volume 16 Issue 2 Pages 83-85
    Published: September 15, 1969
    Released on J-STAGE: June 28, 2010
    JOURNAL FREE ACCESS
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