King of herrings

📖 Overview

Cool-water, anti-tropical distribution, at latitudes greater than 15° . Oceanic and can live at great depths , but occasionally cast up on beaches . Large adults sometimes kill themselves by swimming out of the water onto beaches; occurrence of such strandings may be linked to certain areas, seasons or months and often in spates. With a unique adaptation of self-amputation (autotomy) of the posterior part of the body past the vent which may involve only the caudal fin (or one to a few small adjacent vertebrae) or as far anterior as just before the abdomen; apparently occurs several times during its lifetime (serial autotomy) but do not damage any vital organs and are usually survived except in strandings. All records over 1.5 m long have bodies shortened by autotomy and may exhibit a healed-over stump or "terminus"; still, many specimens found with fresh (with a ragged appearance very different from a healed termini) incomplete self-amputations of the posterior part of the body, notably not consistent with shark bites; the lost part is never regenerated. Species of this Regalecus attain lengths of 7-8 meters and this is well established by documented specimens. Oftentimes vertically suspended head-up in clear oceanic or inshore waters with the rays of the two dorsal fin crests usually extended vertically upwards while the pelvic fin rays may be horizontally spread outward and away from the body . This is hypothesized to be a feeding stance that visually allows the fish to spot the silhouette of its potential prey against the skylight . Feed on euphausiid crustaceans, small fishes and squid . Toothless protrusile jaws work to suction krill-laden water into its oro-branchial cavity and retained in the gullet by the long, spiny and bristly gill rakers . Occassionally associate in pairs (gender undocumented) but no record of group larger than three or of schooling behavior . Spawning occurs between July and December and larvae are encountered near the surface . Mature individuals spawn in the North Atlantic along the west coast of Florida and off the northern coast of America; in or near the Straits of Messina in the Mediterranean; in the South Pacific in the Catham Rise area of New Zealand and somewhere off the west coast of southern Australia . In Guinness Book of Records as longest bony fish . Also caught with encircling nets and marketed fresh . Reputed to be unpalatable because the flesh is tasteless or otherwise unappetizing . Underwater footage shows them slowly swimming vertically, head up, with a stiff body, only undulating the dorsal fin, and with photophores on their appendages. The mouth can be protruded for capturing prey (RF, pers. comm. 2013).

🔬 Taxonomy

🐟 Physical Description

Dorsal spines (total): 0; Dorsal soft rays (total): 414 - 449. Head and body silver in color with blue streaks; body with blackish streaks and spots. Dorsal fins crimson in color and with 10-12 + about 400 soft rays. Pelvic fin represented by a prolonged, ribbon-like ray . Distinguished by the following features: dorsal fin rays until the end of the abdomen numbering 90 to 120; abdominal vertebrae count 45 to 56; in complete specimens: total vertebrae, 127 to 163 and total dorsal fin rays, 414 to 449; total gill rakers on first gill arch in large fish 33 to 47; dorsal fin in adults with 2 crests: first dorsal fin crest with 6 to 8 rays membranously joined and second dorsal fin crest with 5 to 11 elongated and ornamented rays with no fin membranes connecting them or other dorsal fin rays. Other characteristics: cristophore (new term) present and supports the first dorsal fin crest; pelvic fin with a single permanent, extremely elongate and ornamented ray; 11-14 pectoral-fin rays, with a horizontally-oriented base, allowing the fin to be vertically-oriented when adpressed against the body; all large fish lacking a caudal fin, but in the young, principal rays number 3-4 (usually 4), may be extremely elongate, and the tip rarely with ornament; lacking procurrent rays; highly elongate body, with no anal fin; total dorsal fin rays in complete specimens (significantly less in individuals of approx. max. TL of 1.5 m), 3 33 to 449 and total vertebrae 113 to 163; approx. max. length of largest specimens, 8 m (all autotomized); stomach characterized with an elongate postabdominal caecum extending to end of body; muscle masses compartmentalized by a complex system of connected intermuscular septa; with up to three dorsal horizontal septa and three ventral horizontal septa in addition to the horizontal, vertical, and transverse septa common to most teleosts; as a result of autotomy, the posterior part of the adult body (including most large juveniles) terminating in a healed-over stump or terminus (new term); still, many specimens found with fresh (with a ragged appearance very different from a healed termini) incomplete self-amputations of the posterior part of the body, notably not consistent with shark bites. Toothless jaws or with only some tine vestigial teeth .: eel-like.

🌀 Behaviour

Little is known about oarfish behavior. It has been observed swimming by means of undulating its dorsal fin, and also swimming in a vertical position using undulatory movements of both its body and dorsal fin. In 2010, scientists filmed a giant oarfish in the Gulf of Mexico swimming in the mesopelagic layer, the first footage of a reliably identified R. glesne in its natural setting. The footage was caught during a survey, using an ROV in the vicinity of Thunder Horse PDQ, and shows the fish swimming in a columnar orientation, tail downward. A 2016 episode of TV show River Monsters filmed two oarfish, most likely R. glesne, swimming in deep water in the middle of the Mediterranean Sea, off the coast of France. In season 8 episode 1, titled "Deep Sea Demon" (the 47th episode of the series), River Monsters host Jeremy Wade and his crew went to a specific buoy, anchored to the seabed by a single vertical chain, where previous sightings of an oarfish had been reported. At the buoy, the water is approximately 2.4 km (1.5 mi) deep. The rarely-sighted oarfish was reported to occasionally swim up and down the chain, sometimes as close as 9.1 m (30 ft) from the surface. During Wade's second diving attempt, done around nightfall, he successfully saw first one, then two living and healthy oarfish. Wade estimated the first oarfish was roughly 2.5 times Wade's height; unofficial reports list Wade's height as 1.83 m (6.0 ft) tall, meaning the oarfish was roughly 4.57 m (15.0 ft) long. The first oarfish seemed mildly curious but unafraid of Wade; it came close enough that Wade was able to reach out and gently touch it, to which the oarfish barely reacted. A little after this, the second oarfish swam up to Wade, leaving him diving in the water with two extremely rare fish. It is unknown exactly why the oarfish were there, whether they came to that location to feed, or whether or not they were a breeding pair.

🦐 Diet

There is little known about the feeding habits of Regalecus. Most accounts report the stomach and gut as empty, or with colored liquid inside. There is one account of R. glesne with a gut content of thousands of krill. Another report of the stomach contents of two adult R. glesne consisted of 43 heads and 7 individuals of Mediterranean krill.

🥚 Reproduction

Are broadcast spawners with no parental care for the young .

🌍 Habitat & Distribution

Marine; pelagic-oceanic; oceanodromous ; depth range 20 - 1000 m , usually 20 - 200 m . Subtropical; 72°N - 52°S, 180°W - 180°E distributed, including the Mediterranean (Ref.

🌿 Ecology

📐 Morphometrics

🌡️ Water Parameters & Tolerance

🛡️ Conservation Assessment

📊 Population Risk & Fisheries

🌐 Names & Taxonomy

Scientific Synonyms

🐠 Related Species

🔍 Similar Species

🗺️ Global Occurrence Map

Occurrence records from the Global Biodiversity Information Facility (GBIF) - 23 records indexed .

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