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Fig. 3. Ink visualization of the jets generated by the crayfish fan organs.
Bilateral jets directed at 25° and 40° upwards (A) and horizontally
(B); unilateral jet directed horizontally (C). Water-based ink for a fountain
pen was used. After the animal had been observed fanning for about 1 min, the
ink was slowly released from a pipe of 0.6 mm i.d. placed in front of the
animal fan organs. Caution was taken to prevent the ink from getting in
contact with the animal's chemoreceptors. The photo in A was acquired 5 s, and
in B and C, 30 s, after the beginning of the ink injection.