name = Telescopefish
image_width = 220px
image_caption = "
familia = Giganturidae
genus = "Gigantura"
genus_authority = Brauer, 1901
subdivision = "
Telescopefish are small, deep-sea
aulopiform fishcomprising the small family Giganturidae. There are just two known species, both within the genus"Gigatura". Though rarely captured, they are found in cold, deep tropical to subtropical waters worldwide.
The common name of these fish are understandably named for their bizarre, tubular
eyes. The genus name "Gigantura" is in reference to the Gigantes, a race of giants in Greek mythology—coupled with the suffix "oura", meaning "tail", thus "Gigantura" refers to the ribbon-like lower half of the tailfin.
The Giganturidae are slender, slightly tapered fish with large heads dominated by large, forward-pointing telescoping eyes with large lenses. The head ends in a short, pointed snout. The highly extensile mouth is lined with sharp, slightly recurved and depressible teeth and it extends well past the eyes. The body lacks scales but is covered in easily abraded, silvery
guaninewhich imparts a greenish to purplish iridescencein life. The gas bladderis absent and the stomachis highly distensible.
fins are spineless; the deeply forked and hypocercal caudal finis most striking, with the lower lobe extended to a length exceeding that of the body. The pectoral fins are large (ca. 30–42 rays), situated above the gillopening, and inserted horizontally. The anal fin(ca. 8–14 rays) and single dorsal fin(ca. 16–19 rays) are both situated far back of the head. The pelvic fins and adipose finare absent.
Also absent are: the
premaxilla, orbitosphenoid, parietal, symplectic, posttemporal, and supratemporal bones; the gill rakers; and the branchiostegal rays. The loss of these structures is attributed to neoteny; that is, the retention of larval characteristics.
Gigantura indica" is the larger of the two species in terms of length at ca. 20.3 centimetres standard length (a measurement excluding the caudal fin). However, " Gigantura chuni" (at ca. 15.6 cm standard length) is slightly more robust in build.
Telescopefish are presumed to be solitary, active
predators, frequenting the mesopelagic to bathypelagic zones of the water column, from ca. 500 metres down to ca. 3,000 metres. By using their tubular, large-lensed eyes—which are adapted for optimal binocular light collection, at the expense of lateral vision—telescopefish are likely able to spy their prey's weak bioluminescencefrom a distance, as well as (by looking skyward) resolve the outlined silhouettes of prey against the gloom above. Their eyes may also help telescopefish to better judge distance of prey; these visual adaptations are typical of deep-sea fish (cf. barrel-eye, tube-eye). Common prey items include bristlemouths, lanternfish, and barbeled dragonfish. Owing to the telescopefishes' highly extensile jaws and distensible stomachs, they are able to swallow prey larger than themselves; this is also a common adaptation to life in the lean depths (cf. sabertooth fish, black seadevil).
Much less is known of their reproductive habits. They are presumed to be non-guarding pelagic spawners, releasing eggs and sperm indiscriminately into the water. The fertilized eggs are buoyant and become incorporated into the
zooplankton, wherein they and the larvae remain—likely at much shallower depths than the adults—until metamorphosis into juvenile or adult form.
List of fish families
List of fish common names
* [http://www.bio.uib.no/biodoc/pdffiles/pub/1325.pdf "Mesopelagic fishes"] . "Encyclopedia of ocean sciences", Vol. 3, 2001. A. G. V. Salvanes and J. B. Kristofersen. February 2005 version. (PDF file.)
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