抄録
The pelagic gymosomatous pteropod Clione limacina has bipolar distribution, and can be also found in the Sea of Okhotsk and the North Pacific around Japan. In Hokkaido, C. limacina appears on the coast of the Okhotsk Sea when drift-ice comes. It is also possible to collect the species from April to early July off Abashri in the Sea of Okhotsk, when the water temperature is 5℃ to 10℃ or less. Most gymnosomes are oceanic and obtainable only with a plankton net. Keeping live material for a long period in a tank is necesary for biological research. To enable their culture, the following conditions were important: 1) The water temperature is kept at 2℃ in the refrigerator. 2) A 500ml PET bottle is used as a rearing case. 3) Sample size is restricted to a single individual per bottle. The water quality is important in keeping living individuals for a long time. 4) Excrement in the bottle should be regularly removed by pipette. 5) Only one-third of the water should be changed once a month. By these methods, we succeeded in keeing Clione for over one year without feeding. In addition, we tested various chemicals to find an appropriate medium for fixation. The best result was obtained by the following treatment: 1) smearing 25% gultaraldehyde solution on the body using a brush, and 2) fixation in 45% acetic acid at 4℃ after one hour. 5% formaldehyde added to 50% glycerin solution is also useful in the latter stage of fixation. These methods provided good results for histological sectioning and morphological observations. Even one year after fixation, the condition of specimens was unchanged.
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