Scientists have discovered a new species of fish living almost 4 1/2 miles below the surface of the Pacific Ocean.

The ghostly white snailfish was found September 10 in the Peru-Chile trench in the South Pacific by an international team of marine biologists led by Alan Jamieson of the University of Aberdeen in Scotland. The scientists also found cusk-eels and crustaceans living in the trench off the west coast of South America. Those creatures had never before been observed at such depths, where sunlight never penetrates and water pressure is almost 10,000 pounds per square inch.

“Our findings, which revealed diverse and abundant species at depths previously thought to be void of fish, will prompt a rethink into marine populations at extreme depths,” said Jamieson, who led researchers from Japan and New Zealand in the project.

The researchers discovered the creatures during a three-week expedition during which they took more than 6,000 images at depths between 4,500 and 8,000 meters (15,000 to 26,000 feet).

The most recent mission – August 31 to September 20 - was the seventh in three years by a collaborative research project among the University of Aberdeen’s Oceanlab, the University of Tokyo’s Ocean Research Institute and New Zealand’s National Institute of Water and Atmospheric research.

Previous expeditions had identified another species of snailfish in deep-sea trenches off Japan and New Zealand.

“To test whether these species would be found in all trenches, we repeated our experiments on the other side of the Pacific Ocean off Peru and Chile, some 6,000 miles from our last observations,” Jamieson said. “What we found was that indeed there was another unique species of snailfish living at 7,000 meters — entirely new to science, which had never been caught or seen before.”

Jamieson said scientists also observed cusk-eels in a “feeding frenzy that last 22 hours” and large shrimp-like crustacean scavengers in abundance in the trench.

“It begs the question of why and how they can live so deep in this trench but not in any other,” said Niamh Kilgallen, an expert on the creatures at the New Zealand institute.

“These findings prompt a re-evaluation of the diversity and abundance of life at extreme depths," Jamieson said.