The deaths of two giant oarfish that washed up off California within the span of a week may have been caused by an ocean current that the weak-swimming creatures could not overcome, a scientist said.

The 18-foot giant found off Santa Catalina Island on Oct. 13 was among the largest oarfish reported in nearly 20 years. A 14-foot fish beached in Oceanside on Friday was dissected and examined by scientists Monday.

Oarfish, deep-sea dwellers that remain largely mysterious to researchers, have been seen underwater only a handful of times. What is known comes from the few carcasses that have washed ashore.

Despite its menacing appearance, the serpentine, silver fish is toothless and heavy, with weak, flabby muscles. It glows slightly, and a ribbon-like dorsal fin waves along the length of its body as it hangs in the water, sucking down plankton and jellyfish, said Russ Vetter, who assisted in the smaller fish's dissection and directs the fisheries resource division at the Southwest Fisheries Science Center.

The fish aren't adapted to surviving in the more turbulent waters near the shore, and may have perished after being carried away from more still waters, said Milton Love, a research biologist at the Marine Science Institute at UC Santa Barbara

Experts, however, stressed that they have not pinpointed a cause of death.

"With a rare event like this, it is a bit troubling, but it's a total mystery," Vetter said.

The tissue will be divided and sent to research specialists around the world, who will look for clues about the creature and its habitat — its eyes, gills, heart and liver will be studied, its DNA will be sequenced for insight about the fish's evolution and its ear bones will be examined to determine age.

The fish's tissue will be tested for toxins, and data that could indicate low oxygen levels in the water will be examined as they become available, Vetter said.

Results from the research could take years to complete, scientists said.

"People from all around the world are desperate for a piece of tissue," Vetter said.

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samantha.schaefer@latimes.com

Twitter: @Sam_Schaefer