A type of a sea creature known as a nautilus, not seen for more than 30 years and thought perhaps extinct, has been spotted in the South Pacific, researchers say.
Nautiluses -- small, distant relatives of cuttlefish and squid -- are ancient animals, sometimes referred to as "living fossils" because the creatures' distinctive spiral shells have been showning up in the fossil record for the last 500 million years.
The particular nautilus in question, Allonautilus scrobiculatus, was rediscovered in waters of Papua New Guinea's Ndrova Island by University of Washington biologists Peter Ward.
It was a case of meeting a long-lost friend after at long absence; Ward and a colleague were the original discoverers of the creature in the same waters in 1984.
Considered one of the rarest animals on Earth, it hasn't been seen since -- until its recent rediscovery by Ward.
"Before this, two humans had seen Allonautilus scrobiculatus," says Ward, "My colleague Bruce Saunders from Bryn Mawr College found Allonautilus first [in 1984], and I saw them a few weeks later."
At the time, the two scientists collected several specimens and found their shell shape, gills, jaws and other features were different from other known nautilus species.
They had found a new, previously unknown and unnamed species, they realized.
"Some features of the nautilus -- like the shell giving it the 'living fossil' label -- may not have changed for a long time, but other parts have," explains Ward.
There was one additional feature, not found in any other nautilus species, that made it clear they were looking at something new, he says.
"It has this thick, hairy, slimy covering on its shell," Ward says. "When we first saw that, we were astounded."
After one subsequent sighting of Allonautilus by Saunders in 1986, the elusive creatures seemed to disappear -- until July of this year, when Ward made a journey back to Papua New Guinea for a survey of nautilus populations.
Ward and research colleagues lowered baited poles into the water, suspended at depths between 500 and 1,300 feet, along with cameras, and waited.
They were rewarded with footage of an Allonautilus approaching the bait -- the first spotting of the species by Ward in 31 years.
They new how deep to look, Ward says, because the creatures inhabit a narrow range of ocean depths.
"Just like submarines, they have 'fail depths' where they'll die if they go too deep, and surface waters are so warm that they usually can't go up there," he explains. "Water about 2,600 feet deep is going to isolate them."
The New Guinea island is the only place on Earth Allonautilus has ever been found, he says.
"This could be the rarest animal in the world."
