Dragonfishes and Relatives: Stomiiformes

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Dragonfishes and their relatives are famous for having large mouths filled with enormous fanglike teeth. This feature allows the fish to efficiently capture large prey, or animals hunted and killed for food. In some cases, the prey are larger than the predator, or animal that hunts and kills other animals for food. Drag-onfishes and their relatives are about 0.5 to 20 inches (1.3 to 51 centimeters) long. Some species have long, thin bodies, and others are deep-bodied and narrow from side to side.

All but one species of dragonfishes produce light. At the end of chin barbels (BAR-buhls), or long, thin feelers used for the senses of taste, touch, and smell, these fishes have bulblike glowing organs that are thought to serve as lures to other fish. These barbels range in size from less than head length to as much as ten times the length of the fish. Some of these fishes also have rows of light-producing organs along the sides of the body.


Dragonfishes and their relatives live all over the world except the Arctic Ocean.


Dragonfishes and their relatives live in the open ocean at 660 to 3,300 feet (200 to 1,000 meters), but some live below 3,300 feet (1,000 meters).


For their size, dragonfishes and their relatives are fierce predators (PREH-duh-terz) that hunt and kill for food. They feed on other fishes, shrimps, and squid, or they feed on plankton, or microscopic plants and animals.


Little is known about the behavior of drag-onfishes and their relatives, mainly because most of them have never been seen alive. Most species swim from a daytime depth of 1,600 to 3,300 feet (488 to 1,000 meters) to near the surface at night and then back down again before sunrise. This upward migration or movement is thought to be mainly for feeding. Food is much more plentiful near the surface. It is thought that most dragonfishes and their relatives spawn at their deeper daytime depths. Some species have separate sexes, while others mature into males, produce sperm to fertilize (FUR-teh-lyez) eggs, or join with them to start development, and then later develop into females, producing eggs that are fertilized by younger males. In species with separate sexes, males often have a greatly developed sense of smell to help in finding females.


Because of their bizarre and fearsome appearance, dragonfishes and their relatives have been subjects of myth, literature, and art.


Huge fangs allow dragonfishes and their relatives to take prey about one-third their own size. This meal would be equivalent to an adult human eating more than one hundred hamburgers in a single sitting.


The protein responsible for red light production by rat-trap fish has been studied for possible medical uses. This protein, if it could be synthesized and attached to an antibody, would provide a means of locating and treating tumors within a human body without the need for invasive surgery.


Dragonfishes and their relatives are not threatened or endangered.


Physical characteristics: Viperfish can be as long as 14 inches (36 centimeters). The body is long and thin, and the head is large. There are five rows of large scales on each side of the body. The body is iridescent yellowish to blue-green on the sides, dark on the back, and enclosed in a jellylike sheath. This fish has more than fifteen hundred light-producing organs. The dorsal (DOOR-suhl) fin, or the fin along the midline of the back, is well forward on the body. The second ray, or supporting rod, of this fin is much longer than the others and is thought to serve as a fishing lure.

The teeth of the viperfish are so large they do not fit within the confines of the mouth. This fish sees the world through its teeth.

Geographic range: Viperfish live all over the world except the northern Indian Ocean.

Habitat: Viperfish live in the middle to deep depths of the open ocean, migrating closer to the surface at night.

Diet: Young viperfish eat small crustaceans (krus-TAY-shuns), or water-dwelling animals that have jointed legs and a hard shell but no backbone. Adults eat fishes, mainly lanternfishes, and occasionally shrimp.

Behavior and reproduction: Scientists do not know much about the behavior of viperfish except that spawning takes place year-round with a peak in late winter and early spring.

Viperfish and people: Viperfish have no commercial value. Their fearsome appearance has inspired myth, literature, and art.

Conservation status: Viperfish are not threatened or endangered. ∎


Physical characteristics: Rat-trap fish are about 10 inches (25 centimeters) long. They are blunt on the ends, and the dorsal fin and anal (AY-nuhl) fin, or the fin along the midline of the belly, are well back near the tail fin. The body is solid black. The lower jaw is much longer than the skull and holds four pairs of large fangs. The mouths of these fish have no floor. The light organs on the body are very small. The eyes are large, and there is a large, deep-red light organ under each eye. There is no chin barbel.

Geographic range: Rat-trap fish live all over the world.

Habitat: Rat-trap fish live in the middle and deep parts of the open ocean day and night.

Diet: Rat-trap fish mainly eat small crustaceans but sometimes eat fish and shrimp.

Behavior and reproduction: Rat-trap fish can produce red light with the large light organs under their eyes. They can also see red light. Because most deep-sea fishes can see only blue-green wavelengths, this ability helps rat-trap fish search for prey without being seen by predators. Scientists do not know much about the reproduction of rat-trap fish.

Rat-trap fish and people: Rat-trap fish have no commercial value, but they have been studied for medical purposes.

Conservation status: Rat-trap fish are not threatened or endangered. ∎



Hoyt, E. Creatures of the Deep. Buffalo, NY: Firefly, 2001.

Niesen, Thomas M. The Marine Biology Coloring Book. 2nd ed. New York: HarperResource, 2000.

Web sites:

"Dragonfish." All the Sea. http://www.allthesea.com/Deep-Sea-Fish-Dragonfish.html (accessed on September 27, 2004).

"Viperfish." Environmental Literacy Council. http://www.enviroliteracy.org/subcategory.php/231.html (accessed on September 27, 2004).