Perhaps the most notable characteristic of the beryciform fishes is their ability to produce light, and in some cases, readily control it. The light is the result of bioluminescent bacteria that take up residence in pockets just below the skin of various species, including the flashlight, pineapple, and pineconefishes. Other beryciform fishes also have light organs, including members in the genera Sorosichthys and Para-trachichthys. As well as using the light to find and/or to attract
A flashlightfish, with its light organ glowing under its eye in an otherwise dark background. Flashlightfish use the light organ at night to look for prey and to communicate with each other. (Illustration by Wendy Baker)
prey during their nocturnal feeding forays, in some cases these fishes apparently employ the illumination as a means of communication between members of the their own species and as a method of confusing potential predators. This assumption is based on observations of alterations in the blinking pattern of the light when conspecifics approach one another or when a predator swims nearby. The eyelight fish (Photoblepharon palpebratus) can control its light production by lifting or dropping a flap of skin over the light organ. Other species have other ways of controlling the light.
Several beryciform species also make noises, either when interacting with members of their own species or with other fishes. The squirrelfishes are noted for their grunting and clicking sounds, which they produce with the swim bladder.
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