Regalecus russelii

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Regalecus russelii
Regalecus russelii Academia Sinica.jpg
Preserved specimen of R. russelii in Academia Sinica, Taipei
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Lampriformes
Family: Regalecidae
Genus: Regalecus
Species:
R. russelii
Binomial name
Regalecus russelii
Cuvier, 1816
Larve R. russelii 2 days after hatching Larval Oarfish.png
Larve R. russelii 2 days after hatching

Regalecus russelii, or Russell's oarfish, is a species of oarfish in the family Regalecidae. [1] It is a broadly-distributed marine fish, found in waters in the bathypelagic zone. [2] R. russelii is a scaleless, elongate and ribbonlike fish, growing up to 8 meters in length. [2]

Contents

Taxonomy

Regalecus russelii is a member of the fish genus Regalecus and oarfish family Regalecidae. The genus currently includes only one other species of oarfish, Regalecus glesne . [2] [3] R. russelii is part of the order Lampriformes, which represents tube-eyes and ribbonfishes, and is part of the larger class of ray-finned fishes called Actinopterygii. [2]

Anatomy and morphology

Regalecus russelii can grow up to 8 meters in length, and it has two dorsal fin crests that can reach 1 meter high. [2] The species can be distinguished by its red dorsal fin crests, light brown head, and scaleless, silver body. [2] [3] The body is covered by dermal tubercles, which are concentrated along the ventral and lower side regions of the body. [3] Each dorsal fin has 333 to 371 rays, which shorten and then become longer at the middle of the body. [3] [2] Its pelvic fin contains more than three membranous appendages and is a single elongated ray. [2] The stomach has a long caecum, beginning posterior of the abdomen and extending to the end of the body. [2] Muscle is contained in intermuscular septa, with dorsal and ventral septa along with teleost's characteristic horizontal, vertical, and transverse septa. [2] Older R. russelii often have a posterior stump-like tail, which is a consequence of self-amputation but show no signs of regeneration. [2] In some specimens, this tail appears jagged and unhealed, consistent with a fresh self-amputation. [2]

The majority of these fish have toothless jaws, but small vestigial teeth have been observed in some. [2] There are 113 to 122 vertebrae present in the spine. [2] The skeleton contains distinct areas of hyperostosis, or hyper-ossified bones, that are most prominent on the dorsal pterygiophores, but is also present on the cleithrum and along the supraoccipital bone. [4] The rest of the skeleton is cartilaginous. [4] The hyperostosis provides additional support to the pterygiophores during movement. [4] It has also been hypothesized that this hyper ossification acts as a lever for the oarfish dorsal fins, which contributes to the organism's buoyancy. [4] The presence of hyperostosis varies among R. russelii of different ages and sizes; it is present in most large adult fish, and many smaller fish lack these regions of swollen bones. [4] R. russelii's flaccid skeleton lacks mineralization, which is advantageous in maintaining buoyancy in deep waters. [4]

One of the few biological structures that has been studied is the otolith, which is a structure in the inner ear that is involved in sensing movement and gravity. [5] R. russelii have very small sagittal otoliths that are difficult to observe; their small size may indicate that they play an insignificant role in sensing. [5] Researchers have been able to perform CT scans and rare, invasive studies on this structure of a deceased R. russelii to better understand its physiological significance. [5]

Regalicus russelii juvenile.jpg
Regalicus russelii juvenile 2.jpg
Regalicus russelii juvenile 3.jpg
Juveniles, Japan

Life history traits

In addition to the otolith, recent studies have revealed more information about the reproductive organs of the oarfish. Using photographs, histological cross-sections, and measurements of four samples of R. russelii, researchers were able to qualitatively describe the sexual organs of the species. These studies have shown that female oarfish have bifurcated ovaries containing a cavity through which the eggs pass before leaving the body of the oarfish. Testes on male oarfish are located in a similar place as the ovaries of female oarfish, near the digestive tract called the coelomic cavity. The oarfish have two separate, disconnected testes and the left testes observed were longer than the right testes. An analysis of these findings led researchers to conclude that R. russelii are likely batch spawning fish that produce a large number of offspring every breeding season. [6]

Based on a study that performed an artificial insemination with the eggs and sperm from a pair of deceased R. russelii samples, the morphology of the oarfish larvae was able to be examined. This study described the larvae as having long yet compact bodies. The larvae were invertebrates but had bones in their head area, as well as fins. The swimming patterns of the larvae were analyzed, and it was determined that they primarily used their pectoral fins for motility. [7]

Distribution

Regalecus russelii lives in deep waters near areas such as Japan, California, and Baja California, in waters such as the Pacific, Atlantic, and Indian oceans. [2] The oarfish typically reside in the mesopelagic area of the sea. [7] Since 1901, there have been 19 verified sightings and strandings along the coast of California waters. [8] R. russelii is found around the world equatorially, while Regalecus glesne is found with antitropical distribution. [9] Regalecus glesne are termed mesopelagic fish because they spend most of their time at a depth of around 300–1000M. [10]

In June 2022, a juvenile was seen on the Great Barrier Reef off Queensland, Australia, by a snorkel tour leader. Identification was later made from pictures, by Dr Tyson Roberts, a former researcher at the Smithsonian Tropical Research Institute in Panama. [11]

Between January and February 2024, two Russell's oarfish were first found in Thailand in the Andaman Sea. The first was found between Trang and Satun provinces, and the second was found in Phuket. Their remains are preserved in the Natural History Museum. [12] [13]

The low number of live sightings of oarfish has made it difficult to determine the precise distribution of the Regalecus, and further research is needed.

Feeding and diet

The species uses a feeding stance to see the silhouette of its prey. It feeds on euphausiid crustaceans, small fishes and squid, and uses its protrusile jaws to suck in prey. [14] The oarfish mostly consumes a diet of krill [15] as its energy source, using its jaw to fill its oro-branchial cavity with the crustaceans, that will then be held in the gullet and passed through. [16]

Conservation

There are no specific conservation measures for R. russelii, and it occurs in at least one marine protected area. It has been listed as 'Least concern' by the IUCN Red List. [14]

Mythology

In Japanese mythology, oarfish are referred to as "Messengers from the Sea God's Palace" (竜宮の使い ryūgū-no-tsukai).

Two deep sea oarfish were caught live in nets off the coast of Okinawa, Japan January 28, 2019. Both died before making their way into an aquarium inland in the town Motobu. One fisher described the two oarfish squirming in the nets as looking like "real dragons." [17]

Earthquakes

A belief surrounds the species that they are "harbingers of earthquakes", but there is no scientific evidence or an association established between recorded oarfish sightings and earthquakes. [8]

Though Kiyoshi Wadatsumi, an expert in ecological seismology and director of e-PISCO, an organization which studies earthquakes, states that deep sea fish are more sensitive to the tectonic movements or tremors from active faults than fish closer to the surface of the ocean. [18]

From December 2009 to March 2010, unusual numbers of this species of oarfish appeared in the waters and on the beaches of Japan. [19] After the 2011 Tōhoku earthquake and tsunami which killed over 20,000 people, many pointed to the oarfish from 2009–2010 to build up this myth. [20]

Parasites

Despite the relatively limited number of oarfish researched, in 2014 scientists were able to discover a new species of nematode called Spinitectus gabata (Spirurina: Cystidicolidae) within the gastrointestinal tract of a R. russelii off the coast of Japan. S. gabata likely uses the krill the oarfish consumes as an intermediate host, since known Spinitectus species often involve crustaceans as intermediate hosts. [15]

A recent study concerning the parasitization of this species revealed that the shortfin mako shark and the sperm whale could both be predators of the oarfish, based on patterns of parasite transmission. [21] These conclusions were made based on analysis of the visceral tissue of an oarfish recovered by the Catalina Island Marine Institute in Santa Catalina Island, California. [21]

Related Research Articles

Lampriformes is an order of ray-finned fish. Members are collectively called lamprids or lampriforms, and unite such open-ocean and partially deep-sea Teleostei as the crestfishes, oarfish, opahs, and ribbonfishes. A synonym for this order is Allotriognathi, while an often-seen, but apparently incorrect, spelling variant is Lampridiformes. They contain seven extant families which are generally small but highly distinct, and a mere 12 lampriform genera with some 20 species altogether are recognized. They are the only extant members of the superorder Lamprimorpha, which was formerly diverse throughout much of the Late Cretaceous.

<span class="mw-page-title-main">Dorsal fin</span> Fin on the dorsal of fish and cetaceans

A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through convergent evolution they have independently evolved external superficial fish-like body plans adapted to their marine environments, including most numerously fish, but also mammals such as cetaceans, and even extinct ancient marine reptiles such as various known species of ichthyosaurs. Most species have only one dorsal fin, but some have two or three.

<span class="mw-page-title-main">Oarfish</span> Pelagic lampriform fish belonging to Regalecidae

Oarfish are large and extremely long pelagic lampriform fish belonging to the small family Regalecidae. Found in areas spanning from temperate ocean zones to tropical ones, yet rarely seen, the oarfish family contains three species in two genera. One of these, the giant oarfish, is the longest bony fish alive, growing up to about 8 m (26 ft) in length.

<i>Lophius</i> Genus of fishes

Members of the genus Lophius, also sometimes called monkfish, fishing-frogs, frog-fish, and sea-devils, are various species of lophiid anglerfishes found in the Atlantic and Indian Oceans. Lophius is known as the "monk" or "monkfish" to the North Sea and North Atlantic fishermen, a name which also belongs to Squatina squatina, the angelshark, a type of shark. The North European species is Lophius piscatorius, and the Mediterranean species is Lophius budegassa.

<span class="mw-page-title-main">Crevalle jack</span> Species of fish

The crevalle jack, also known as the common jack, black-tailed trevally, couvalli jack, black cavalli, jack crevale, or yellow cavalli is a common species of large marine fish classified within the jack family, Carangidae. The crevalle jack is distributed across the tropical and temperate waters of the Atlantic Ocean, ranging from Nova Scotia, Canada to Uruguay in the western Atlantic and Portugal to Angola in the eastern Atlantic, including the Mediterranean Sea. It is distinguishable from similar species by its deep body, fin colouration and a host of more detailed anatomical features, including fin ray and lateral line scale counts. It is one of the largest fish in the genus Caranx, growing to a maximum known length of 124 cm and a weight of 32 kg, although is rare at lengths greater than 60 cm. The crevalle jack inhabits both inshore and offshore waters to depths of around 350 m, predominantly over reefs, bays, lagoons and occasionally estuaries. Young fish dispersed north by currents in the eastern Atlantic are known to migrate back to more tropical waters before the onset of winter; however, if the fish fail to migrate, mass mortalities occur as the temperature falls below the species' tolerance.

<span class="mw-page-title-main">Ceratiidae</span> Family of fishes

Ceratiidae, the warty sea devils, caruncled seadevils or seadevils, are a family of marine ray-finned fishes belonging to the suborder Ceratioidei, the deep-sea anglerfishes, in the anglerfish order Lophiiformes. The warty sea devils are sexually dimorphic with the small males being obligate sexual parasites of the much larger females. The fishes in this family are widely distributed from polar to tropical seas around the world.

<span class="mw-page-title-main">Giant oarfish</span> Species of oceanic ray-finned fish

The giant oarfish is a species of oarfish of the family Regalecidae. It is an oceanodromous species with a worldwide distribution, excluding polar regions. Other common names include Pacific oarfish, king of herrings, ribbonfish, and streamer fish.

<span class="mw-page-title-main">Sillaginidae</span> Family of fishes

The Sillaginidae, commonly known as the smelt-whitings, whitings, sillaginids, sand borers and sand-smelts, are a family of benthic coastal marine fish historically classified in the order Perciformes, although the 5th edition of Fishes of the World places the family in the Spariformes. The smelt-whitings inhabit a wide region covering much of the Indo-Pacific, from the west coast of Africa east to Japan and south to Australia. The family comprises only five genera and 35 species, of which a number are dubious, with the last major revision of the family in 1992 unable to confirm the validity of a number of species. They are elongated, slightly compressed fish, often light brown to silver in colour, with a variety of markings and patterns on their upper bodies. The Sillaginidae are not related to a number of fishes commonly called 'whiting' in the Northern Hemisphere, including the fish originally called whiting, Merlangius merlangus.

<span class="mw-page-title-main">Bonefishes</span> Family of fishes

Albulidae is a family of fish, commonly known as the bonefishes, that are popular as game fish in Florida, select locations in the South Pacific and the Bahamas and elsewhere. The family is small, with 11 species in 3 genera. Presently, the bonefishes are in their own order: Albuliformes. The families Halosauridae and Notacanthidae were previously classified in this order, but are now, according to FishBase, given their own order Notacanthiformes. The largest bonefish caught in the Western Hemisphere is a 16-pound, 3 ounce example caught off Islamorada, Florida, on March 19, 2007.

<span class="mw-page-title-main">Yellowtail scad</span> Species of fish

The yellowtail scad, is an abundant species of small inshore marine fish of the jack family, Carangidae. The species is widespread in the Indo-Pacific region from east Africa in the west to Hawaii in the east, extending north to Japan and south to Australia. The yellowtail scad is the only member of the monotypic genus Atule and is distinguished from similar species by a well-developed adipose eyelid and finlet-like extensions of the last rays of the dorsal and anal fins. It inhabits coastal areas such as bays and coral reefs, preying on small fishes and crustaceans. Spawning has been well studied in Hawaii, where fish enter bays to spawn, releasing up to 161,000 eggs each between March and October. The yellowtail scad is an important component of fisheries throughout its range, taken by a number of netting and hook-and-line methods. It is a prized food fish in some regions and is cooked or preserved by a variety of methods.

<i>Lutjanus</i> Genus of ray-finned fishes

Lutjanus is a genus of marine ray-finned fish, snappers belonging to the family Lutjanidae. They are found in the Atlantic, Indian, and Pacific Oceans. They are predatory fish usually found in tropical and subtropical reefs, and mangrove forests. This genus also includes two species that only occur in fresh and brackish waters.

<span class="mw-page-title-main">Rhadinorhynchidae</span> Family of worms

Rhadinorhynchidae is a family of parasitic worms from the order Echinorhynchida.

<i>Regalecus</i> Genus of fishes

Regalecus is a fish genus of the family Regalecidae, commonly called oarfish, with these currently recognized species:

<i>Agrostichthys</i> Species of fish

Agrostichthys parkeri, also called the streamer fish, is a species of oarfish. Only seven identified specimens have been examined, with few found fully intact, and have mainly been found in the Southern Ocean. Agrostichthys parkeri belongs to the Regalecidae (oarfish) family in the Lampriformes order and is the only known member of its genus. This species has been known to grow up to 3 metres (9.8 ft) long and has a ribbon-like body, two large eyes, a protruding mouth and long filamentous rays originating at the head. Due to only seven specimens being found, only the distribution and anatomy of Agrostichthys parkeri can be documented.

<i>Pterois russelii</i> Species of fish

Pterois russelii, the largetail turkeyfish, plaintail firefish, plaintail turkeyfish, Russell's firefish, Russell's lionfish, spotless butterfly-cod or the spotless firefish, is a species of ray-finned fish with venomous spines belonging to the family Scorpaenidae, the scorpionfishes and lionfishes. It is native to the Indo-Pacific Ocean from the eastern part of Africa to the Persian Gulf.

<i>Lutjanus russellii</i> Species of fish

Lutjanus russellii, Russell's snapper, Moses snapper, fingermark bream, Moses seaperch or Russell's sea-perch, is a species of marine ray-finned fish, a snapper belonging to the family Lutjanidae. It is native to the western Pacific Ocean.

<i>Argyropelecus olfersii</i> Species of fish

Argyropelecus olfersii is a common species of marine hatchetfish, found in mesopelagic waters.

Spinitectus is a genus of nematodes belonging to the family Cystidicolidae.

<i>Gymnocanthus pistilliger</i> Species of fish

Gymnocanthus pistilliger, the threaded sculpin, is a species of marine ray-finned fish belonging to the family Cottidae, the typical sculpins. This species occurs in the northern Pacific Ocean.

Rhadinorhynchus mariserpentis is a species of parasitic thorny-headed worm within the family Rhadinorhynchidae. The species is a endoparasite of Regalecus russeli, with the type locality coming from an intestine of an individual collected in the Sea of Japan off the coasts of northern Kyushu.

References

  1. 1 2 "WoRMS - World Register of Marine Species - Regalecus russelii (Cuvier, 1816)". www.marinespecies.org. Retrieved 2019-03-28.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 "Regalecus russelii summary page". FishBase. Retrieved 2019-03-28.
  3. 1 2 3 4 Angulo, A.; López-Sánchez, M. I. (2017). "New records of lampriform fishes (Teleostei: Lampriformes) from the Pacific coast of lower Central America, with comments on the diversity, taxonomy and distribution of the Lampriformes in the eastern Pacific Ocean". Zootaxa. 4236 (3): 573–591. doi:10.11646/zootaxa.4236.3.11. PMID   28264321.
  4. 1 2 3 4 5 6 Paig-Tran, E.W.; Barrios, A.S.; Ferry, L.A. (2016). "Presence of repeating hyperostotic bones in dorsal pterygiophores of the oarfish, Regalecus russellii". Journal of Anatomy. 229 (4): 560–7. doi: 10.1111/joa.12503 . PMC   5013060 . PMID   27296623.
  5. 1 2 3 Midway, S.R.; Wagner, T. (2015). "The first description of oarfish (Regalecus russellii Cuvier 1816) (Regalecidae) ageing structures". Journal of Applied Ichthyology. 32 (1): 113–116. doi: 10.1111/jai.12967 .
  6. ↑ Forsgren, Kristy L.; Jamal, Homam; Barrios, Andrew; Paig-Tran, E.W. Misty (September 2017). "Reproductive Morphology of Oarfish ( Regalecus russellii ): OARFISH REPRODUCTIVE MORPHOLOGY". The Anatomical Record. 300 (9): 1695–1704. doi: 10.1002/ar.23605 . PMID   28390152. S2CID   205413717.
  7. 1 2 Oka, Shin-ichiro; Nakamura, Masaru; Nozu, Ryo; Miyamoto, Kei (2020-04-08). "First observation of larval oarfish, Regalecus russelii, from fertilized eggs through hatching, following artificial insemination in captivity". Zoological Letters. 6 (1): 4. doi: 10.1186/s40851-020-00156-6 . ISSN   2056-306X. PMC   7140580 . PMID   32292594.
  8. 1 2 Feeney, Richard F.; Lea, Robert N. (December 2018). "California Records of the Oarfish, Regalecus russelii (Cuvier, 1816) (Actinopterygii: Regalecidae)". Bulletin, Southern California Academy of Sciences. 117 (3): 169–179. doi:10.3160/3294.1. ISSN   0038-3872. S2CID   91283288.
  9. ↑ Chakrabarty, Prosanta (2013). "Systematics, Biology, and Distribution of the Species of the Oceanic Oarfish Genus Regalecus (Teleostei, Lampridiformes, Regalecidae)". Copeia. 2013 (2): 336. doi:10.1643/OT-12-165. ISSN   0045-8511. JSTOR   24635733. S2CID   85635714.
  10. ↑ Benfield, M. C.; Cook, S.; Sharuga, S.; Valentine, M. M. (July 2013). "Five in situ observations of live oarfish Regalecus glesne (Regalecidae) by remotely operated vehicles in the oceanic waters of the northern Gulf of Mexico". Journal of Fish Biology. 83 (1): 28–38. doi:10.1111/jfb.12144. ISSN   0022-1112.
  11. ↑ Oarfish spotted on the Great Barrier Reef during snorkel swim, Phil Brandel, ABC News Online, 2022-07-02
  12. ↑ "Highlight Activities 2024: First of Regalecus russellii (Cuvier, 1816) (Teleostei:Regalecidae) from the southwestern Thailand". Faculty of Science, Mahidol University (in Thai). 2024-08-26. Retrieved 2024-07-16.
  13. ↑ "Museum upbeat as dead Oarfish offers opportunity to increase scientific knowledge". The Nation . 2024-08-26. Retrieved 2024-02-20.
  14. 1 2 "The IUCN Red List of Threatened Species". IUCN Red List of Threatened Species. Retrieved 2019-03-28.
  15. 1 2 Poinar, George; Weinstein, Sara; Garcia-Vedrenne, Ana; Kuris, Armand (2014). "First description of a nematode, Spinitectus gabata n. sp. (Spirurina: Cystidicolidae), from the deep sea oarfish, Regalecus russelii (Regalecidae) in Japan". International Journal of Nematology. 24 (2): 117–123.
  16. ↑ "Regalicus russelii" . Retrieved 2020-03-11.
  17. ↑ "Okinawan fishermen reel in two live oarfish, eat portion of one". The Japan Times Online. 2019-02-17. ISSN   0447-5763 . Retrieved 2020-03-11.
  18. ↑ Yamamoto, Daiki (2010-03-06). "Sea serpents' arrival puzzling, or portentous?". The Japan Times Online. ISSN   0447-5763 . Retrieved 2020-03-11.
  19. ↑ Yamamoto, Daiki (4 March 2010). "Sea serpents' arrival puzzling, or portentous?". Kyodo News. Retrieved 6 March 2010. TOYAMA — A rarely seen deep-sea fish regarded as something of a mystery has been giving marine experts food for thought recently after showing up in large numbers along the Sea of Japan coast.
  20. ↑ Alex Stambaugh and Junko Ogura. "Pair of rare oarfish discovered alive in Japan". CNN. Retrieved 2019-02-24.
  21. 1 2 Kuris, Armand M.; Jaramillo, Alejandra G.; McLaughlin, John P.; Weinstein, Sara B.; Garcia-Vedrenne, Ana E.; Poinar, George O.; Pickering, Maria; Steinauer, Michelle L.; Espinoza, Magaly; Ashford, Jacob E.; Dunn, Gabriela L. P. (February 2015). "Monsters of the Sea Serpent: Parasites of an Oarfish, Regalecus russellii". Journal of Parasitology. 101 (1): 41–44. doi:10.1645/14-581.1. ISSN   0022-3395. PMID   25220829. S2CID   32384405. Closed Access logo transparent.svg
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