Thursday, October 4, 2012

56' of Sea Serpent

What's the longest fish on record? The oarfish, Regalecus is the longest bony fish in the oceans today, holding the record of 17 meters (56') in length. Seems like something that big would have a hard time hiding, so why have most people never heard of or seen something that large?

Some sailors in the US Navy pose with a dead oarfish (1996; from Wikipedia)

Oarfish live at depths up to 3,280 feet (1,000 m), although they're more typically found at around 656 feet (200 m). They rarely venture to the surface unless they're injured or dying. Occasionally, one of these giant eely fish will be tossed onto a beach after a storm. Their eggs can be seen during spawning season from July to December in the northern hemisphere. They release the brightly coloured, buoyant eggs (up to 6 millimetres (0.24 in) across) which are incorporated into the zooplankton. The eggs hatch after about three weeks into highly active larvae that feed on other zooplankton.

Drawing of the sea serpent-like oarfish
With their long, tapering body, smooth silvery skin (they don't have scales), and red dorsal fin that runs from the eye down the entire length of the body, oarfish are the most likely source of tales of sea serpents. Their dorsal fin is composed of 400 rays, the first 10-12 of which are elongated and flow from the head like a mane. Their pelvic fins are also elongated and end in a fleshy tab. It was once believed they rowed themselves through the water with these pelvic fins, thus the name oarfish. They actually swim by undulating their long dorsal fin while keeping the body straight (as do sea horses). Similar to sea horses, oarfish have been observed swimming in a vertical position in what is believed to be a method used to search for prey.

A dead oarfish washed up on a beach in Perth, Australia
Oarfish are found in temperate to tropic seas, but as mentioned, they're rarely seen because of their preferred depth. In fact, the first time a swimming oarfish was caught on video was in 2001! You can see parts of that on this You-Tube video.

Oarfish have no teeth and feed on plankton, so they're no threat to humans, and humans are no threat to them since their mushy flesh isn't very tasty. Still, I might think twice about jumping into the water with a 56' long fish!!
Oarfish. Image from Wikipedia.

For more information on the oarfish, see:
Hendrickson, R. (1984). The Ocean Almanac. Doubleday, NY. 446 pp.