Captive Spirula hang head-downward in the water. This species is able to withdraw its head and arms completely within the mantle; the mantle opening can then be closed by folding over the large dorsal and ventrolateral extensions of the mantle margin. The photophore at the posterior end of the body is known to glow for hours at a time. When the animal is swimming slowly downward, head first, its terminal fins are pointed upward (i.e. posteriorly) and move with a rapid "waving or fluttering motion" that propels it downward (Bruun, 1943).
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