Oarfifsh – Regalecus russellii

Regalecus russellii, commonly known as the oarfish, is a species of deep-sea fish belonging to the family Regalecidae. It is one of the longest bony fishes in the world, with specimens reaching impressive lengths. These enigmatic creatures are known for their ribbon-like bodies and distinctive red crests, often leading to sightings being mistaken for mythical sea serpents.

Description & Characteristics

Regalecus russellii can grow to a maximum length of 800.0 cm, with an elongated, compressed body that resembles an oar. Its silvery-grey skin is covered in small scales, and it possesses a prominent dorsal fin that extends the entire length of its body. The first few rays of this fin are elongated and form a distinctive red crest, which can be mistaken for a crown when viewed from a distance. This crest, along with its long, narrow body, has contributed to the species’ association with sea serpent myths.

Habitat and Occurrence

Regalecus russellii is a deep-sea fish that typically inhabits the mesopelagic and bathypelagic zones, ranging in depth from 200 to 1,000 meters. These zones are characterized by low light levels and high pressure, making them challenging environments for most marine life. Despite this, the Regalecus russellii is a relatively common inhabitant of these depths, with its presence often being noted in the Atlantic, Indian, and Pacific Oceans.

Taxonomy

Regalecus russellii belongs to the Class: Teleostei, Order: Lampriformes, and Family: Regalecidae. This family is known for its unusual morphology and deep-sea adaptations, including the presence of elongated dorsal fins and specialized feeding mechanisms. The Order Lampriformes includes other notable deep-sea fishes, such as the opah and the ribbonfish.

Feeding

Regalecus russellii is a carnivore, with a diet consisting primarily of zooplankton, small fish, and squid. Its feeding habits are not fully understood, but it is believed to use its long, slender body to sweep through the water, catching prey with its small mouth. The species’ large, sensitive head and distinctive crest suggest that it may also be able to detect prey through vibrations in the water column.