The oarfish is thought to be the longest known species of bony marine fish. It has a long, thin body growing to more than 36 feet (11 m). The oarfish has a scaleless silver body with black to brown markings along the sides. It has a large dorsal fin that starts at the head and runs the length of the oarfish's body. The dorsal fin ranges in color from bright pink to deep red. Until the first video footage was captured of a live oarfish, it was widely thought that the fish propelled itself through the water by undulating its whole body; it is now known this is not true and that they actually propel themselves by undulating the dorsal fin while the body remains mostly stationary.
Caught on film by the United States Navy for the first time in 2001, the oarfish remains a modern day mystery. Although there are occasional sightings, there has been no conclusive research into the life of this species. This fish is thought to only be found on the surface when ill or close to death, and the majority of information gathered comes from the examination of dead specimens found washed ashore on beaches across the world. Sometimes caught by recreational fishermen, the oarfish is not commercially fished because the flesh is unpalatable.
Regalecus glesne is the scientific name given to the giant oarfish. There is a debate within the scientific community surrounding whether there is only one true species or up to four known species. So little is known about the oarfish that it is difficult to know for certain. Differences between specimens could just be a result of localized adaptations of the same species across such a large geographic range. Differences in markings could also be localized variations, and it is known that the markings fade and disappear after death, which could be another factor in species recognition.
The oarfish is thought to be a solitary creature, living in all temperate to tropical oceans. It is to be found at depth of 600 feet (200 m) to more than 3,000 feet (1,000 m). This species is thought to be predominantly carnivorous, eating plankton, squid and smaller fish. Oarfish are not listed as endangered, largely because not enough is known about their numbers and any potential threats to the population to make an accurate judgment. The size and bizarre, somewhat menacing appearance of the oarfish, as well as the rarity of sightings, had led to a widely held theory that sightings of oarfish gave rise to the widespread myths about sea monsters and giant sea serpents.