The Oarfish

I’m going to take a break from the topic of catfishes to post an overview of the lovely and mysterious oarfish.  This topic also serves as an appropriate follow-up to a previous post concerning the largest fish ever, for, in the present era, Oarfish are either the longest bony fish in the world or the longest fish outright (depending on the source).  The Guinness Book of Records recorded a specimen of the oarfish Regalecus glesne which measured 17 meters (56 feet) long.  If correctly recorded, that fish’s length surpassed the length of the largest confirmed whale shark–which was 12.65 metres (41.50 ft) long. However Regalecus glesne specimens more usually measure 11 meters or less. Other species of oarfish do not attain such great sizes: Regalecus russelii usually measures a maximum of 5.5 meters and Agrostichthys parkeri, the streamer fish, seldom exceeds 3 meters.

A 23-foot long Oarfish that washed up at the Naval Training Center, Coronado Island, Calif, September 1996.

Oarfish are solitary animals which live deep in the pelagic zone of the ocean (the pelagic zone is the part of the ocean which is neither close to the shore nor to the bottom).  They swim through the great open waters of the oceans frequenting depths of about 200 meters–although they lack a swim bladder and may sometimes swim much deeper into the abyssal portions of the ocean.  Like many other ocean giants, oarfish are filter feeders and subsist on zooplankton, tiny crustaceans, and the occasional jellyfish, or squid. Because their regular habitat is so remote for humans, oarfish are seldom seen at all (and those that do get spotted are usually sick, dying, or dead).  In days before the internet, their rarity provided fodder for tragicomic tales of yokels mistaking them for sea serpents. Oarfish are covered with irregular blue and black squiggles which fade when they die, as does their silver iridescence. In addition to their great length, oarfish are notable for their beautiful red and pink dorsal fins.  The first few rays of these fins are very long and give the fish the appearance of wearing a crown (hence the family name Regalecidae—the regal ones). Oarfish obtained their common name from the mistaken belief that they “rowed” through the water using their elongated pelvic fins.  The fish actually move by undulating body-length dorsal fins. Six species of oarfish are known to science, although the creatures are so rarely encountered that undiscovered species or genera may exist.

A rare photo of a live oarfish. Oarfish are known to orient themselves vertiically in this manner--perhaps to search for food.

Oarfish painted by Judith Pryor

Like many teleosts, oarfish go through a larval stage immediately after they hatch from the egg.  During this time the tiny transparent fry possess an appearance greatly different from their adult counterparts.  They hunt among the zooplankton which they gobble up with extensible mouths.  Nothing is known of how oarfish spawn. It is also not known how long they live or what their habits are in the great blue expanses of the ocean.

larva of oarfish Regalecus glesne

An oarfish nearing adulthood.