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| Oarfish | |
|---|---|
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| King of herrings | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Lampriformes |
| Family: | Regalecidae |
| Genera | |
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Agrostichthys Regalecus |
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The common name oarfish is presumably in reference to either their highly compressed and elongated bodies, or to the former (but now discredited) belief that the fish "row" themselves through the water with their pelvic fins.[4] The family name Regalecidae is derived from the Latin regalis, meaning "royal". The occasional beachings of oarfish after storms, and their habit of lingering at the surface when sick or dying, make oarfish a probable source of many sea serpent tales.
Although the larger species are considered game fish and are (to a minor extent) fished commercially, oarfish are rarely caught alive; their flesh is not well regarded due to its gelatinous consistency.
Contents
Anatomy and morphology
Like other members of its order, the oarfish has a small yet highly protrusible oblique mouth with no visible teeth. The body is scaleless and the skin is covered with easily abraded, silvery guanine. In the streamer fish (Agrostichthys parkeri), the skin is clad with hard tubercles. All species lack gas bladders and the number of gill rakers is variable.
Oarfish coloration is also variable; the flanks are commonly covered with irregular bluish to blackish streaks, black dots, and squiggles. These markings quickly fade following death. The king of herrings is by far the largest member of the family at a published total length of 11 metres (36 ft) (with unconfirmed reports of 15 metres (49 ft) or more) and 272 kilograms in weight. The streamer fish is known to reach 3 metres (9.8 ft) in length whilst the largest recorded specimen of Regalecus russelii measured just 540 centimetres standard length.
Distribution
The members of the family are known to have a worldwide range. However, specific encounters with live individuals in situ are rare and distribution information is collated from records of oarfishes caught or washed ashore.[4]Ecology and life history
Rare encounters with divers and accidental catches have supplied what little is known of oarfish behaviour and ecology. Apparently solitary animals, oarfish may frequent significant depths up to 1,000 metres (3,300 ft). An oarfish measuring 3.3 metres (11 ft 4 in) and 63.5 kg (140 lb) was reported to have been caught on 17 February 2003 by Ms Val Fletcher using a fishing rod baited with squid, at Skinningrove, United Kingdom.[5]A photograph on display in bars, restaurants, guesthouses and markets around Laos and Thailand that is captioned, "Queen of Nāgas seized by American Army at Mekhong River, Laos Military Base on June 27, 1973 with the length of 7.80 metres," is a hoax. The photograph was taken by Dr. Leo Smith of The Field Museum, of an oarfish found in late 1996 by United States Navy SEAL trainees on the coast of Coronado, California, USA.[6][7]
Behavior
In 2001 an oarfish was filmed alive and in situ: the 1.5 metre (5 ft) fish was spotted by a group of U.S. Navy personnel during the inspection of a buoy in the Bahamas.[8] The oarfish was observed to propel itself via an amiiform mode of swimming; that is, rhythmically undulating the dorsal fin whilst keeping the body itself straight. Perhaps indicating a feeding posture, oarfish have been observed swimming in a vertical orientation, with their long axis perpendicular to the ocean surface. In this posture the downstreaming light would silhouette the oarfishes' prey, making them easier to spot.In July 2008, scientists captured footage of the rare fish swimming in its natural habitat in the Gulf of Mexico. It is the first ever confirmed sighting of an oarfish at depth, as most specimens are discovered dying at the sea surface or washed ashore. The fish was estimated to be between 5 m (16.5 ft) and 10 m (33 ft) in length.[9]
As part of the SERPENT Project, five observations of apparently healthy oarfish Regalecus glesne by remotely operated vehicles were reported from the northern Gulf of Mexico between 2008 and 2011 at depths from within the epipelagic and mesopelagic zones.[10] These observations include the deepest verified record of R. glesne (463–492 m) and the first record of an arthropod ectoparasite (isopod).[11]
From December 2009 to March 2010, unusual numbers of the slender oarfish Regalecus russelii[12] (竜宮の使い “Ryūgū-No-Tsukai”,) known in Japanese folklore as the Messenger from the Sea God's Palace, appeared in the waters and on the beaches of Japan; the appearance of which is said to portend earthquakes.[13]
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