| Research Abstract |
Melanin-concentrating hormone (MCH) was shown to act on chromatophores through its specific receptor on the membrane of the effector cells. Upside- down catfish is a curious fish, which usually swim upside-down, as its common name signifies. Its ventral skin contains melanophores, which are controlled, like those on dorsal skin, by both sympathetic nervous and endocrine systems. Greenish hue as displayed by some damselfishes, including scalycheek and blue- green damselfishes, is realized by the presence of blue spots against yellowish background. Both blue and yellow are based on multiple layered thin film interference phenomenon of the non-ideal type, occurring in the peculiar iridophores there. Mainly through histological observations on the distribution of visual cells in the retina, the visual acuity of the lateral eye was examined. It was deduced that the fish sees another one as homogeneously green entity, if the object is more than 2 cm apart. Many bitterling species possess green vertical stripes on the lateral part of the trunk. Working mainly on the rose bitterling, we could show that iridophores were primarily responsible for its coloration. When the band is viewed from the level of the fish, golden hue with higher reflectance damonates. If the angle of depression or elevation increases, the tone shifts to blue through blue-green. These phenomena are due to special arrangement of reflecting platelets in the iridophores. In schools, individuals of this species make orderly ranks by seeing others' band. That is, they seem to keep their positions by recognizing the bright-colored stripe of others swimming nearby. The conclusion was that the band is of great importance for their schooling behavior.
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