The name "viperfish" is also sometimes applied to the lesser weever.
A viperfish is any species of marine fish in the genus Chauliodus. Viperfish
are characterized by long, needle-like teeth and hinged lower jaws. A typical
viperfish grows to lengths of 30 to 60 cm. Viperfish stay near lower depths in
the daytime and shallower depths at night, primarily in tropical and
temperate waters. Viperfish are believed to attack prey after luring them within
range with light-producing organs called photophores, which are located along the
ventral sides of its body, and with a prominent photophore at the end of a
long spine in the dorsal fin reminiscent of the illicium of the unrelated deepsea
anglerfishes. The viperfish flashes this natural light on and off, at the same
time moving its dorsal spine around like a fishing rod and hanging completely
still in the water. It also uses the light producing organ to communicate to
potential mates and rivals. Viperfish vary in color from green,
silver, to black. A viperfish uses its fang-like teeth to immobilize prey and
would not be able to close its mouth because of their length, if it were not
able to fold and curve them behind its head. The first vertebra behind the head
of the viperfish absorbs the shock of biting prey. As with other deepsea fish,
they are able to undergo long periods with scarcely any food.
Viperfish are believed to live from 30 to 40 years in the wild, but in
captivity they rarely live more than a few hours. Some species of dolphins and
sharks are known to prey upon viperfish. Scientists believe they can swim at a
speed of two body lengths per second, but this is not yet an official speed.
Although it may look like it is covered in scales, it in fact is covered by a
thick, transparent coating of unknown substance Extremely large, fang-like
teeth gives the fish a slightly protruded lower jaw which makes catching
prey easy for this deep-sea predator. The viperfish is lined with three
different types of photophores which some speculate is used to lure in
unsuspecting prey They have microscopic spheres without a pigment layer that are
scattered over the dorsal side, large spheres with a pigment coat, reflectors,
and lens, and finally, large, bell-shaped organs with a pigment coat,
reflectors, and lens that are grouped together in rows along the dorsal
surface. Photophores can also be seen along the ventral and lateral surface of
the fish Habitat
Because viperfish live in bathypelagic environments inaccessible to humans,
very little is known about their habits. They are found from a depth of 1000 to
4000 meters with an average temperature of 4 degrees Celsius. Viperfish are
thought to engage in a daily vertical migration, as they have been observed in
the mesopelagic region during the night, which lies directly above the
bathypelagic region. More direct observation is needed to confirm this
assumption, however. Feeding
Viperfish do not appear to have any preferred prey: stomach contents of
captured individuals have contained lanternfish, bristlemouthes, and other
fish, suggesting that they attack and swallow whatever random prey they
encounter. With their dark coloration, they can appear invisible and have been
observed to remain motionless for hours ready to strike on unsuspecting prey
Prey is captured and killed by being pierced by the viperfish's long teeth as
the prey is grasped in the viperfish's mouth: subdued prey is then swallowed
whole. The photophores along the viperfish's belly are thought to help
lure prey closer to it, though further observation is need to confirm this
hypothesis. Species
There are currently nine, extant, recognized species in this genus:
Chauliodus barbatus Garman, 1899 Chauliodus danae Regan & Trewavas, 1929
Chauliodus dentatus Garman, 1899 Chauliodus macouni T. H. Bean, 1890
Chauliodus minimus Parin & Novikova, 1974
Chauliodus pammelas Alcock, 1892 Chauliodus schmidti Ege, 1948
Chauliodus sloani Bloch & J. G. Schneider, 1801
Chauliodus vasnetzovi Novikova, 1972 At least two more species are recognized
from Late Miocene-aged fossils: Chauliodus eximus,, originally Eostomias
eximus,, from Late Miocene California Chauliodus testa, Nazarkin, 2014, from
the Late Miocene of Western Sakhalin Island
References