Viperfish

Viperfish are of the genus Chauliodus. They are recognized by their big hinged jaw and large teeth. They are a deepwater fish. They possess bioluminescent organs, like other stomiiforms, to lure prey. Since they live in such deep water and humans can't get to them they are deemed harmless.

Anatomy
The viperfish come in shades of blue, green, black, and silver. They have an adipose fin and a split caudal fin. The dorsal fin is located just behind the head. Most of the fins contain a soft fin (flexible, jointed ray supporting a fin). The first soft ray on the dorsal fin is about the length of half the fish itself. It has a really big mouth with long fang-like teeth, that do not fit inside its mouth.  Other fish can't see the viperfish's teeth in the dark, so they act as an invisible trap.  The sides of its body is covered with hexagonal pigmented areas. Each of these areas has one or two small photophores. The viperfish has a low lipid content, about 2.4%. The fact that they vertically migrate at night and have a low lipid content suggests that they might have some sort of swim bladder. They are supposed to have a low BMR (Basal Metabolic Rate) on account of they only eat once every 12 days. The photophores along the sides of the viperfish cast out a purple hue with red dots. The viperfish cannot be brought to the surface because it lives under such great pressure, they usually die when they are brought to the surface. They also need to be stored properly to keep from decay. Its vital organs can be located between the two sides of the lower jaw. The viperfish is also able to increase the size of its stomach in order to digest its prey, if it is bigger than itself. It never chews its prey even though it has long fang-like teeth. It is also believed that some hover at a forty-five degree angle.  Viperfish have straight intestines and are able to distend their stomach. Since they have a large mouth and hinged fangs they are able to rotate inward to keep prey from escaping. They have a hinged connection between their skull and backbone and are able to rotate the skull upward to allow the easier passage of large prey

Reproduction
Viperfish larvae look some what like the larval form of of eels. They are about 6mm in length when they hatch from the egg. The length of time it takes for the viperfish to fully develop is unknown. The reproductive habits of the viperfish are pretty much unknown. Whether they are sexually dimorphic or not is undetermined, because the specimens caught are not usually sexed. Since different species contain certain specific photophores it is assumed that light emission is used in mate attraction. Chauliodus sloani are only able to produce few offspring. Spawning most likely happens all year, even though the number of larvae is higher in the months January to March.

Ecology
Viperfish live in the sea at depths between 1500ft to 9000ft. Chaulidous sloani eat an array of different organisms such as; crustaceans, bony fish, Cyclothone, Bregmaceros, Diaphus, Lampanyctus, and Myctophoum are examples of nektonic organisms that the viperfish eats. Some of the bigger viperfish are piscivores, which means they only eat other fish. They get food by curving their first soft ray, on their dorsal fin, in front of their mouth to act as a lure.

Bioluminescence
Viperpish are supposed to have approximately three hundred and fifty luminous organs, which are located along its sides. They use these to attract prey so they can catch them easily, it is also supposed to be used for attracting mates and communication.

Related References

 * taxonomy
 * Viperfish Chaulidous sloani Bloch and Schneider, 1801 Australian Museum Fish site
 * Osteichthyes Salmoniformes Chauliodontidae AnEmaW Animal Electromagnetism and Waves
 * viperfish wikipedia
 * Chauliodus macouni Pacific viperfish Fishbase
 * Chauliodus sloanianimal diversity