HAWAI‘I – US scientists have discovered what might be new coral species and a very rare octopus on an underwater expedition to an previously unexplored extinct volcano in the deep ocean off Hawai‘i

Diving in a submersible to the previously unexplored Cook seamount, an extinct volcano at the bottom of the sea 160km south-west of Hawaii’s Big Island, the three-person team was hoping to examine the rich variety of marine life that collects around the nutrient-rich volcanic waters.

Among other things, the researchers from the University of Hawaii and the nonprofit group Conservation International spotted such wonders as a rare type of octopus with big fins that look like Dumbo’s ears, and a potentially new species of violet-hued coral they dubbed Purple Haze.

Conservation International hopes to study 50 seamounts, or undersea volcanoes, over the next five years.

“We don’t know anything about the ocean floor,” said Peter Seligmann, chairman, CEO and co-founder of Conservation International.

“What we know is that each one of those seamounts is a refuge for new species, but we don’t know what they are. We don’t know how they’ve evolved. We don’t know what lessons they have for us.”

“We don’t know what we’re going to find,” echoes Conservation International’s Greg Stone. “There will always be the unexpected when you go into the deep ocean.”

Halfway down to the volcano, which rises four kilometres from the ocean floor, no sunlight penetrated.

The only light that could be seen from the submarine’s face-sized windows was the bluish glow of the vessel’s own bright lights. Occasionally, bioluminescent creatures drifted past in the darkness.

Stone and sub pilot Terry Kerby, who helps run the Hawai‘i undersea research laboratory at the University of Hawai‘i, watched as the volcano and its rugged basalt walls came into view.

Seamounts are either active or dormant volcanoes that rise from the bottom of the ocean and never reach the surface.

They are hotspots for marine life because they carry nutrient-rich water upward from the sea floor. Seamounts are believed to cover about 18 million square miles of the planet.

Cook seamount is part of a group of undersea volcanoes known as the Geologist Seamounts that are about 80 million years old and could hold many new animal species, as well as elements such as nickel and cobalt that mining companies could extract.

“My goal today is to find out what’s living on them, find out how they support ocean life, what their effect is from ocean currents and essentially what drives the ocean, what makes the ocean what it is,” said Stone.

“Seamounts are a key part of that, and something which humanity knows very little about.”

Within minutes of the vessel’s arrival at the summit– 900 metres below the surface – life begins to appear – a starfish clinging to a rock, joined shortly after by eels, sharks, chimaera (also known as “ghost sharks”), shrimp, crabs and two rare Dumbo octopuses.

One of the octopuses changed colour from white to pink to reddish brown as it swam by.

Several types of deep-sea corals were found along the seamount’s cliffs, including a vibrant purple one.

“I need to go home, look through the literature and also go and run some genetic analyses,” said Sonia Rowley, a postdoctoral researcher at the University of Hawai‘i who is taking part in the project.

“But as this is a new seamount that no one had dived on before, it won’t be any surprise to me whether this is going to be a new species.”

Two other seamounts were studied over three days of expeditions – McCall, home to a large number of small deep-sea sharks, and Lo‘ihi, an active volcano.

Lo‘ihi has been extensively surveyed by manned submersibles over the past 30 years. The past few times Kerby was there, he saw a large Pacific sleeper shark lurking about the volcano’s crater.

As hot vents shot out volcanic gases around them, the team released bait in the water and the seven-foot shark appeared in front of the submarine. Kerby was delighted to see his “old friend” again.

The team also saw two-metre-long eels and a number of new geological formations around the crater. Scientists say Lo‘ihi is likely to someday become the newest island in the Hawaii chain as volcanic activity pushes the summit upward.

- Associated Press