Viper Fish

The viperfish is one of the fiercest predators of the deep. It’s scientific

name is Chauliodus sloani. The viperfish’s name comes from its fang

resemblance to the Viper Snake. The viperfish, which typically grows to at least

a foot long, has a very large mouth, which opens very widely but is not big

enough to contain the fish's long teeth. The viperfish is also bioluminescent, with

photophores light-emitting organs on its dorsal fin and along its body to lure its

prey to it. The fish has been observed hovering in place in the water with its

dorsal fin curved around so that its photophore is waving near its mouth, as a

means of drawing prey. Because the viperfish's body is dark blue or black in

color, it is thought that other fish can see no part of it other than its lights.

The viperfish uses swimming for locomotion. It has been known to impale

its victims on its teeth by swimming toward them, while using its first vertebra as

a shock absorber. The viperfish’s diet consists of shrimp, squid, and little fishes.

The viperfish is found at depths of 500-2500 meters during the day in the part of

the ocean sometimes called the "twilight zone," because very little light

penetrates to that depth. When it goes in search of the crustaceans and small

fish that are its main sources of food at night; it rises as close as to the surface

as 80 meters where food is more plentiful. The Viperfish occurs in tropical and

temperate marine waters world-wide. In Australia, specimens have been

collected from south-western Western Australia, around the north of the country

and south to Tasmania.

An adaptation that the viperfish has made is the dorsal fin has

photophores that are believed to attract prey. Little is known of the reproduction

of this species, but it is believed to spawn externally. This means that the males

and females release sperm and eggs into the water where fertilization occurs.

Chauliodus sloani inhabit depths that make them very difficult to study.