The Deep-sea dragonfish is a member of the Stomiidae family. There are many genera and over two hundred different species altogether in the Stomiidae family. The most known about is the Barbeled Dragonfish. This dragonfish lives in the deep parts of the Atlantic Ocean beyond where any plant life grows or light reaches. This habitat has caused the Dragonfish to adapt to the conditions at these depths by having light-producing organs called photophores and skeletons that better suit deep-sea life.
Environment
The Deep-sea Dragonfish, as the name states, lives in the deep-sea of the Atlantic ocean. The Dragon fish tends to live around 1500 to 4500 meters below the surface. Some Dragonfish have even been found at depths of 5000 meters. At these depths, the conditions are very extreme. The pressure can range from 200 to 600 atmospheres (atm) and the temperatures fall just below four degrees Celsius. The Dragonfish lives below the Bathyal zone where no light reaches. The Bathyal zone starts at about 220 meters. Past this point, there is no light, and it is deep enough to not be affected by storms or ocean currents, making the environment where the dragonfish lives utterly still.
Description
To deal with the pressures, the dragon fish has a very minimalized skeleton except for the jaws and other parts used for feeding. They have large, recurved teeth that can either be tightly bound or hinged, allowing them to fall inward while eating, depending on the species. The dragonfish also has a second set of jaws located in the branchial basket, which houses the gills as well as this second set of jaws. The dragonfish has a very odd characteristic in that certain genera of dragonfish are missing the two through seven vertebras in their spine. This has been found to be due to the developmental characteristics of the dragonfish. In most fish, the spine develops from head to tail, but in dragonfish it develops in the opposite direction. These missing vertebras allow the dragonfish to have an increased flexibility in their head, allowing them to eat larger prey. The dragonfish, like other deep-sea predators, have light producing organs called Photophores along their body and on a flesh like extension of the lower jaw called a barbell. These photophores are also found on the pectoral fins. The dragonfish, unlike most fish, has a scaleless body. Their body has a slimy, flesh-like outside very similar to an eel.
Feeding
The Dragonfish is a predator since no plant life grows at the depths where the Dragonfish lives. The Dragonfish feeds primarily on marine fish and deep sea invertebrates. It uses the photophores on its body and its barbell to attract its prey before it’s snapped up into their jaws.
Special Characteristics
The deep-sea dragonfish has a special characteristic from most of its fellow deep-sea creatures. Most deep sea fish that can produce light produce blue light, but the dragon fish can produce not only blue light but a red light as well. This red light is emitted from a suborbital photophore. In order to see this red color, these dragonfish have two different visual pigments.This characteristic is only found in three genera of dragonfish: Malacosteus, Aristostomias, and Pachystomias. As a result, they are carnivores.
References
- Froese, Rainer, and Daniel Pauly, eds. (2006). "Stomiidae" in FishBase. January 2006 version.
