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Bioluminescence was observed in the ascidian, Clavelina miniata (Tunicata: Ascidiacea). This is the first report of luminescence in ascidians. A green light was evoked by mechanical stimulation, by increasing the concentration of K+ ions, or by hypotonic conditions. The source of the light was a type of tunic cell (cell type II). This luminescence is attributed to an intrinsic system, not to bacterial symbionts.
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Aoki et al. (1989) studied this question.
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