It may never be known for certain what killed two giant oarfish in the US within a week of each other.
But one scientist suggests that an unusual ocean current may have brought the deep-water creatures toward the Southern Californian shore, where they got trapped in shallow waters and died.
Oarfish, the world's longest bony fish, are rarely seen dead or alive. They live in deep ocean waters, up to 3,000 feet (914m) below the surface, and are difficult to study for that reason. Only recently have scientists captured video of an oarfish swimming in the Gulf of Mexico.
The carcass of a 14-foot-long (4m) oarfish washed ashore in Oceanside, California, on October 18, just five days after a dead 18-foot-long (5m) oarfish - among the biggest seen in two decades - was discovered off Catalina Island.
The timing of the two events is very strange, says Russ Vetter, a director at the Southwest Fisheries Science Center.
The smaller fish was cut up into four large pieces, each about 27kg, before it was carted off in a pickup truck by Vetter's team to be dissected in the lab.
The fish seemed to be perfectly healthy when it died, Vetter said. It did not appear to be malnourished, diseased, or have any marks or indications of outside trauma from things like fishing gear or a boat propeller.
Because of the fish's apparent health, the cause of death may be due to an unusual ocean current that brought the fish close to shore, he said.
Oarfish are not thought be strong swimmers. To swim they use a small fin that runs along the whole length of the body instead of moving their entire body. The fish may have not been strong enough to escape the unfamiliar shallow waters it was trapped in.
"Compared to tuna or salmon, the meat is very watery," said Vetter, who was examining an oarfish for the first time in his life.
"The meat was also very white meat, another sign that it is not a strong swimmer." Meat that is made of muscles that are exercised often has a darker colour.
This fish probably died on the day it was found because it was in such good condition.
DNA samples were taken from the fish to determine its closest living relatives. The gills, stomach, and ovaries will be studied by researchers in California, while the eyes went to an expert in Australia.
"The whole fish got used," said Vetter.
