Eoarfish is one of the most common species that exist in all temperate and tropical zones of the world. Its scientific name is Regalcus glesne and belongs to the Regalecidae family, within the Lampridiformes order. In popular literature it is also known as king of herrings due to its elongated appearance and its relationship within that lineage. They are established in marine waters practically all over the world. It is considered one of the longest bony fish in the world, reaching 17 meters in length in unverified reports and with Confirmed records around 11 meters.
A fish this long looks more like a monster than a regular fish, so it's worth getting to know it better: unique morphology, calm behavior, cosmopolitan distribution, and countless interesting facts that have made it the subject of marine legends. Want to learn everything about this fish?
Characteristics of the oarfish
Although it is a fish that is about 17 meters in length, It is not the biggest fish in the world. It has a large dorsal fin that gives it a completely unusual, snake-like shape. Its silhouette is tapered and very slender, which reduces drag in the water and allows it to remain stable with a gentle undulation of its long dorsal fin.
It is not a dangerous animal, given its rather calm behavior. Because it almost always remains in the depths, not too well known of this fish. They are able to travel to the surface when they are about to die or are extremely sick, or when environmental changes push them to shallower depths.
Its body is quite slender and flattened, which is why it is also known as the sabrefish. It has no scales; instead, it presents a silver guanine sheath covered with slimy skin. Although its mouth is protruding, does not show its teeth and is fed mainly by gill rakers specialized companies.
Its dorsal fin is very large. It runs from the top of the eyes to the end of the tail. It turns red or pink and practically occupies the entire body. The dorsal fin has about four hundred thorns (rays), twelve of which are elongated in the cephalic region, creating a very striking crest. This fin is its main driving force: it undulates to propel itself both horizontally and vertically.
The pelvic fins have tapered and elongated elements, and in their shape They resemble an oar (hence its common name). On the head, the first dorsal rays They extend and form a crest unmistakable red. On the other hand, its pectoral fins are very small, difficult to see, and its caudal and anal fins are very small, which explains its slow swimming style.
In addition to its appearance, it stands out for some internal details: it usually presents between 40 and 58 gill rakers, structures in the gill arches that act as a filter and "rake" for small prey. Their eyes are well developed to capture light in mesopelagic environments and its silver coloring provides camouflage through reflections that dissipate contours.
Behavior of the Regalecus glesne
As mentioned before, the oarfish is a very calm fish. You could say it's a shy fish that's embarrassed to draw attention to itself. When it's stalked by predators, it flees to the depths and takes refuge among the rocks or in the water column, far from the illuminated surface. It spends most of its life in the depths. swimming adrift and protecting itself from predators with its slim profile and silver color.
They use their dorsal fin to swim, often vertically. They can be found in the depths. swimming vertically, a behavior that could help them confuse predators or prey by aligning themselves with the light coming from above. They can also swim horizontally, as they have a very efficient locomotion system that allows them to perform various maneuvers to change direction and sense thanks to the undulation of the dorsal fin.
They are generally solitary fish and can rarely be seen near other specimens of the same species. They can be seen in small groups when they move to another habitat, although they do not remain together, but rather they keep a distance relative. Its pelagic nature makes its encounters sporadic and its observation complicated.
Most of the time they can be found floating near the shores because are swept away by ocean currents when they are already sick or old and are not able to resist the waves. In these cases, their large size and serpentine shape feed stories of sea monsters, (as do stone fish because of its sinister appearance), although in reality the oarfish is harmless.
In situations of intense stress against predators, some specimens show a phenomenon called partial autotomy (self-detachment of the tail end), which reduces length and surface area to facilitate escape. This ability, described in field observations, is interpreted as an extreme survival strategy.
Habitat and area of distribution
The saber fish inhabits depths at about 1000 meters, although it can approach more superficial layers and also descend to the deep mesopelagic zone. Thanks to its ability to tolerate a wide temperature range (including temperate waters), it can be found in almost all the world's oceans, except for the polar zones. It is generally a migratory fish, so it does not remain in one area for long, and its distribution is considered cosmopolitan.
They travel great distances between different bodies of water to seek food and shelter and escape predators. They are capable of moving from depths of 20 meters to 1000 meters relatively quickly. There are records of presence as far north as latitudes near 72° N and as far south as around 52° S, most frequently in tropical regions of temperate oceans.
Its presence is conditioned by the availability of prey in the water column, especially aggregations of krill and other crustaceans, so it is believed that many of their movements respond to trophic impulses and currents that concentrate plankton. This pattern supports the idea of opportunistic migratory behavior.
When they approach the surface they usually do so in a punctual and brief, or in a state of weakness. In such circumstances, they may strand on beaches and be found by fishermen or bathers, which has given rise to a large number of viral sightings on the coasts of different countries.
Meals
Their diet is fully carnivorous. They enter their diet squid, small fish, crustaceans and even planktonIt requires great effort to capture prey, as it must use its gills with specialized gill rakers to retain its prey. This filter-feeding and ambush feeding system is efficient in deep waters where available energy is limited.
As it does not have a developed functional dentition, can't bite forcefully to its prey. But as evolution is very intelligent, this species has adapted to this: what it lacks robust teeth, it compensates with gill rakers designed for hunting. They have a rake-like shape and are used for pull and hold small prey comfortably.
By swimming vertically, you gain an advantage over other fish, such as the flying fish (which moves horizontally near the surface). In a vertical position it can position itself below of schools or shoals of krill and gently ascend to engulf them with its protractile mouth, reducing the chances of being detected.
It is suspected that it adjusts its trophic habits to the daily vertical migration cycles Zooplankton (which rises at night), which would explain why some specimens are observed closer to the surface during low-light hours. This behavior maximizes energy efficiency by coinciding with times of greater food availability.
Can you eat oarfish?
Despite its size and the fact that it is occasionally caught in sporting activities or as fortuitous find, the oarfish no commercial fishingIts meat is described as gelatinous and little appreciated gastronomically, so it is not considered edible in conventional markets. For conservation and health reasons, it is not recommended to consume stranded fish, as they are usually weakened or decomposing.
Reproduction
Although little is known about this fish, it is known that the spawning season takes place between July and December. This is when They lay a greater number of eggs. The size of these oscillates around 2,5 millimeters and they are thrown towards the surface where they keep floating until they hatch.
The oarfish is fertilized externally, since the eggs are fertilized outside the female's bodyThe male remains close to the female to protect her from danger and promote fertilization. When the female releases her eggs, the male releases his sperm and fertilizes them.
When the eggs hatch, the larvae remain good weather in areas close to the surface until they are dragged by the currents to the bottom. The larvae already have a developed dorsal fin and elongated conformation, and feed on microcrustaceans during their early stages. Once they reach deeper layers, they continue their development until they reach the juvenile stage and, later, adulthood.
The age of sexual maturity and longevity remain poorly documented topics, partly due to the difficulty in studying this species in its natural habitat and the scarcity of direct observations of its complete life cycle.
Curiosities of the saber fish
The oarfish has a characteristic that makes it special and different from the rest. de peces and it is not its length. Is about the ability to self-amputate a limb (partial tail autotomy). It was assumed that it did this by biting its own tail to free itself from its predator. However, it cannot do this because lacks a set of teeth suitable for this. What happens is that it can detach the distal part of its body to escape and then heal. It can do this on more than one occasion throughout its life.
Another popular curiosity is its relationship with the bad omensIn Japanese tradition it is known as Ryugu no tsukai, the “messenger of the palace of the sea god”. Hence, culturally, the arrival of several oarfish to the coast is associated with earthquakes and tsunamisAlthough this belief is widespread, it does not exist. conclusive scientific evidence that links its appearances with natural disasters.
Where does the idea come from? Some experts have proposed that deep-sea fish could be sensitive to vibrations and changes physicochemical changes associated with tectonic activity (such as ionic variations or the presence of oxidizing compounds in the water). These hypotheses, defended by researchers in ecological seismology and animal biology, suggest that certain changes in the deep marine environment could stress the fish and force them to ascend. However, other studies They have not found correlations robust between strandings de peces rowing and seismic events, so the scientific community maintains a cautious stance.
Beyond the legends, the oarfish is harmless to humans and plays an ecological role as a consumer of small fish and crustaceans. Its serpentine appearance and imposing size may explain many of the stories surrounding it since ancient times.
At the taxonomic level, its genus name Regalecus means "belonging to the king", a nod to his nickname of king of the herrings. The specific epithet glesne It refers to a Nordic toponym linked to historical findings of the species.
As you can see, the oarfish is a true survivor and well worth getting to know. With a ribbon-like body, an endless dorsal fin, and life strategies fine-tuned to the darkness of the ocean, this bony giant epitomizes the wonderful diversity of pelagic life: discreet, resilient and shrouded in myths that invite us to discover its reality with a scientific eye.