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Stomiids make up the large evolutionary group called dragonfishes, scaly dragonfishes, loosejaws, snaggletooths, and viperfishes. For the most part, these fish are elongate and very darkly pigmented. With few exceptions, there are no scales, and the skin resembles dark velvet, often with small light organs scattered over it. Nearly all dragonfishes have a barbel extending from the lower jaw, which is controlled by muscles from behind the jaw bones and is movable; its function can only be estimated, but it is likely used as a lure to attract prey and as a signaling device for communication. Many stomiids have extremely large teeth, of wild design. In the viperfish, the lower jaw teeth actually extend over the head. Many can eat large prey and have bodies able to allow food to pass into the gullet with extremely muscular stomachs. These are lined with black tissue so their incandescent light organs, which run along their bodies, will not shine through, exposing them to predators.

A significant feature of the stomiid evolution has been these light organs with the pectoral fins. The function of such lights is also thought to be prey attraction and communication among member species. Their skeletons is modified to be especially mobile, suggesting that the lights are waved about to further attraction.

The black dragonfish is one of the most extreme of the dragonfishes, in terms of history and body size. The female larvae get quite large, up to 7 centimeters (2 ¼ inches). However, their most distinctive feature is the presence of the elongated stalk eyes that extend from the head, a distance of nearly one-third of the body length. As the larva transforms into a juvenile and begins to approach adult body shape, the eye rods are absorbed and the eyes move into sockets in the skull.

Another group of dragonfishes is a sometimes called loosejaws, in reference to the lack of skin between the lower jaws. There is a slender column of muscle and tissue, between the gill basket and lower jaw; contraction of the muscle pulls the mouth shut.

The dragonfish continues to be held in a combination of wonder and awe in today’s society as one of the most imposing looking fish of the sea.