Giant Oarfish (Regalecus glesne) have been in the news again recently. Two washed up dead on the coast of California in October, one at Santa Catalina, the other near San Diego. They are lousy swimmers, and probably got caught in coastal currents they couldn’t fight successfully.
A dead giant oarfish is still a remarkable thing. These two were 4-5 meters long, but they can grow to as long as 11-12 meters No other bony fish species grows longer.
They are also rarely seen by humans, so every corpse is a new source of amazement. Normally the fish are pelagic, living well off shore, probably usually in deep water – their large eyes suggests adaptation to the deep dim world a few hundred meters below the surface.
And there the mystery of this fish remains. Cruising through the science articles that mention them usually just describe another dead animal that has washed up somewhere new.
The little information we have suggests they spend their time hovering vertically in the water, propelled slowly by a long and undulating dorsal fin while the rest of the body doesn’t move. You really need to see this to believe it: a robot camera captured one a couple of years ago.
We know they they are toothless, lack scales, and have small mouths. As they hover vertically, they are probably feeding, sucking in plankton and euphausids or krill and straining them from the water they push through their gill-rakers. Perhaps they somehow eat small fish. They certainly can’t chase down prey, and they grow too large to be prey for most other fish besides sharks. Somehow they don’t turn up in fishermen’s nets very often, and in fact seem able to avoid the nets.
What else? Their meat tastes mushy, gelatinous, so they are safe from human predation. There are perhaps 4 different oarfish species of different sizes around the world. They have been observed, usually dead, most often in warm-temperate waters. An old quote: “A dead oarfish is about as tough as wet cardboard.”
And the myths? Perhaps they change gender as they grow larger (many fish do). Perhaps they shed the ends of their tails the way some lizards do (maybe the ends just fall off more quickly from dead animals). Perhaps they are the source of mariners’ tales of huge sea serpents (those seen at the surface are usually sick or dying, and could perhaps have inspired the mariners). Perhaps they are especially sensitive to Earth tremors – for example, before the 2011 tsunami in Japan, 20 beached themselves and died (who knows?).
Probably none of these are true, but we really lack the facts that dispel most myths.
What we have here is a most bizarre fish, rarely observed alive and healthy, of no commercial value to us. It probably isn’t endangered, though it certainly is not abundant. It shares this planet with us, mostly out of our view, which is the safest place for it to be. It is a reminder that life on Earth is incredibly diverse, and that not only do we not know everything about everything, but that in fact perhaps we don’t need to know.
It just is.