Using a robotic lander, scientists have captured the first-ever footage of marine life at the bottom of the previously unexplored New Hebrides trench in the Pacific. At depths reaching 4.5 miles, the ecology was unlike anything the marine biologists had ever seen.
The 30-day expedition was conducted by the University of Aberdeen's Oceanlab and the National Institute of Water and Atmospheric Research in New Zealand.
The lander, operating at a depth of 23,000 feet (7,000 meters), was loaded with bait to lure the deep-sea creatures into view.
The resulting video showed an unexpected dearth of diversity; animals observed included large grey cusk eels (some as long as one meter long), bright red prawns (shown directly above), and arrow-tooth eel pouts (shown above that one).
The scientists were surprised to discover an utter lack of some of the most common deep sea fish. The BBC's Rebecca Morelle quotes Dr. Alan Jamieson from Oceanlab:
"Anywhere else around the Pacific Rim, around the trenches we've looked at, you see a lot of grenadiers - they are quite a conspicuous part of the deep-sea community. But when we went to the New Hebrides trench, we didn't see a single one.
"But what we did see was a fish called the cusk eel. These turn up elsewhere but in very, very low numbers. But around the New Hebrides trench, these - and the prawns - were all that we saw."
There was also an absence of snail fish, a small pink fish usually seen in the deepest depths of ocean trenches.
The researchers believe the differences are driven by how nutrient-rich the region of ocean above the trenches is.
"If you look at the New Hebrides trench, and where it is geographically, it lies under very unproductive waters - there is not a lot happening at the surface of the tropical waters," said Dr Jamieson.
"It seems the cusk eels are specialists in very low food environments, whereas the grenadiers require a greater source of food."
"We're starting to find out that what happens at one trench doesn't necessarily represent what happens in all the trenches." — Alan Jamieson