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Species of Pterygioteuthis are probably the smallest of all oceanic squids (Oegopsida). P. microlampas, for example, has a maximum size of 23 mm ML and short arms. One of the most distinctive features of the genus is the presence of a photophore on each eye that has a lid that can open and close over the organ. This photophore can produce a brilliant flash. The lid, presumably, allows a sudden beginning and end to the flash and, when closed, conceals the reflector that lies behind the photogenic tissue. Concealment is important as the reflector otherwise could reveal the squids presence in dark waters to predators that use luminescent search lights. A second pair of flashing photophores that lacks lids is located at the base of the gills. These latter organs are much larger than their counterparts in Pyroteuthis; the size difference is present in paralarvae and is helpful in distinguishing paralarvae of the two genera (Young, et al., 1992).
Members of the genus also have a distinctive hectocotylized arm that contains a peculiar toothed plate and large swollen regions containing folded, glandular tubes of unknown function (Chun, 1910).