A rare nautilus called Allonautilus scrobiculatus has been sighted for the first time in three decades. Until now, only two people had ever laid eyes on it. Peter Ward, a biologist at the University of Washington and colleague Bruce Saunders of Bryn Mawr College identified Allonautilusin 1984, and Saunders made another brief sighting in 1986, but it hasn’t been recorded since. The pair collected several specimens and found they were a new species based on their gills, jaws, shell shape, and male reproductive structures.
The nautilus is a pelagic marine mollusc of the cephalopod family Nautilidae. They are the only living descendent of a group of ocean creatures that thrived in the seas 500 million years ago when the earth’s continents were still forming and are known as living fossils due to them having remained virtually unchanged for millions of years.
It was in July of this year that Ward returned to the South Pacific to survey nautilus populations and was once again reunited with this rare species. Since nautiluses are expert scavengers, Ward and his colleagues set up “bait on a stick” systems each evening — fish and chicken meat suspended on a pole between 500 and 1,300 feet below the surface — and filmed activity around the bait for 12 hours.
“We started using this approach in 2011,” said Ward. “This year, there were about 30 guys involved and each day we would all watch the movies from the night before at 8X speed. There were a lot of ‘ohs’ and ‘ahs’.”
One night’s footage from a site off of Ndrova Island showed an Allonautilus approach the bait. The team also used baited traps to capture several nautiluses, including Allonautilus, at a depth of about 600 feet. Since most nautiluses do not like the heat, the researchers brought them to the surface in chilled water to obtain small tissue, shell and mucous samples and measure the dimensions of each animal. They then transported the animals back to their capture site and released them.
“It’s only near this tiny island,” said Ward. “This could be the rarest animal in the world. We need to know if Allonautilus is anywhere else, and we won’t know until we go out there and look.”
Nautili are found in international trade primarily for their shells and meat. In addition, their shells are prized by collectors around the world and they are harvested for the aquarium trade. Due to their life history characteristics, it is believed that chambered nautilus could be vulnerable to trade. Nautilus species are also threatened by habitat degradation as their native reefs are polluted and destroyed by destructive fishing practices and development.
Header Photo Credit: Nautilus pompilius (left) swimming next to a rare Allonautilus scrobiculatus (right) off of Ndrova Island in Papua New Guinea. PETER WARD