We're learning some amazing things from those massive washed-up oarfish

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Remember those oarfish that washed ashore a few weeks ago in California? Scientists are busy at work studying these elusive serpent-like sea monsters, and they're discovering a lot about their ecology and habitat, including what they eat — and what's eating them.

Above image: A second oarfish that washed ashore near Oceanside, California. AP photo/Mark Bussey.

Recently, two oarfish washed ashore (one off Santa Catalina Island on October 13, and one near Oceanside on October 18), prompting some, quite ridiculously, to worry that it was sign of a pending earthquake. More seriously, however, scientists are using the opportunity to learn more about this remarkable fish.


Oarfish sightings are extremely rare, and so to are physical finds. Maybe one every few years. So when samples are recovered, scientists get really excited. And these two specimens have got biologists completely buzzing, including a team of parasitologists working at UC Santa Barbara.


Parasites Tell Tales

The UCSB researchers were able to secure small samples of tissue from the Santa Catalina oarfish, including gills, intestine, stomach, spleen and gallbladder. Their analysis shows that oarfish are a majorly parasitized fish — and that they're regularly eaten by sharks. So even at depths of 650 to 1,000 feet, life for the world's largest bony fish is not without its headaches. And indeed, this new analysis is revealing much more than who's leeching off them — it's also revealing much about their ecology and habitat as well.


While looking at the oarfish's intestine, the researchers discovered a significant amount of larval tapeworms. One of them was about 6-inches (15 cm) long. They also found a couple dozen tapeworms in the small segment, along with two juvenile roundworms. And surprisingly, they found the hooked proboscis of an adult spiny-headed worm lodged in the intestine as well.

These are important clues for parasitologists; by looking at the precise life cycle stages of parasites, researchers can deduce who the natural enemies of oarfish are, and where the elusive oarfish are likely to live or hunt for food.


Parasites live out their life cycles in different hosts. The larval tapeworms, which weren't fully developed, will stay in the larval stage indefinitely until the oarfish gets eaten by a shark, after which time they enter into their maturation phase. As for the spiny-headed worm, it was consumed by the oarfish, probably via krill or some deep-water crustacean that hosted its juvenile form.

Much More to Come

This UCSB study is the first of what will be several more to come. As Nature News recently reported, the Oceanside fish was X-rayed and several parts of it have already been claimed by various researchers. The heart has gone to a scientist who studies cardiac function, the gills are being looked at by a respiratory physiologist, and the stomach and other tissues are being analyzed to determine its diet.


The rest of the fish, which has been chopped-up into nine easy pieces, is now in a freezer to prevent decomposition. The next step will be to run it through a computerized tomography (CT) scanner so that researchers can create a three-dimensional model of the oarfish's anatomy — a remarkable creature that swims vertically. And genetic data will help researchers determine how many species of this animal exist; some believe that there are at least two distinct species.

[ University of California | Nature News ]