Two years ago, three miles beneath the surface of the sea about 60 miles south of Grand Cayman, scientists found creatures that had never been seen before. 

Now, they’re back for more. 

A group of 23 scientists on board the US Atlantis research ship started out on a three-week expedition on 6 January to continue exploring hydrothermal vents that may give clues about the beginning of life, as well as provide information for the NASA space agency on exploring the possibility of life on Jupiter’s frozen moon, Europa and other planets or moons. 

In an email sent from the ship to the Observer on Sunday on Friday, 13 January, Chris German, the expedition’s chief scientist, said: “So far, we have had a week of great weather and three fantastic dives. Dive one to the Von Damm site [1.4 miles deep] not only found the abundant shrimp we already knew were there but also two different kinds of tube worms living alongside each other and the shrimp at some of the vents in that area. 

“These are cool because they are the first tube-worms to be found at hydrothermal vents in the Atlantic/Caribbean but tube-worms (not the same species?) are often one of the most prominent macro-fauna just the other side of the Isthmus of Panama along the Galapagos Rift and northern East Pacific Rise.  

“With the samples we have in hand we’ll be able to investigate how closely related these tube worms might be to both those Pacific vent-animals and also to tube worms known from cold-seeps associated with the nearby Gulf of Mexico to the northwest.” 

He said the expedition was “not just about biology”, but also about the geology and chemistry of the two sites they are exploring. 

“On our second dive, we explored the world’s deepest vent-sites at around 5,000 metres [three miles]... these are not quite the world record, although at just over 400 degrees Celsius they are certainly in the top 10. And the chemistry of both sites, shallow and deep, have very interesting compositions that are helping inform us as to what the sources of heat at both sites must be.  

“What is also clear is that there are oodles of mineral deposit here so what is happening today has either being going on for a very long time here, just south of [Cayman] (the most likely interpretation) or else has been even more vigorous in the past,” he said. 

Vents 

Researchers in 2010 spotted and captured samples of marine life crowding around vents that spew murky scalding hot water half a mile upward. These are known as “black smokers”.  

This month, they revealed more of their findings, which included a new species of shrimp with light sensors instead of eyes. 

Some members of that team from the 2010 expedition returned this month to the Cayman Trough to continue their exploration of the thermal vents. 

They are using a deep-diving robot called Jason to explore the deep and expect to find several more new species in a part of the ocean that has never been thoroughly explored.  

Jon Copley, a marine biologist who was on board the TSS James Cook, the ship that took scientists on the 2010 expedition, says he is looking forward to seeing what the latest expedition discovers. 

“We can’t wait to hear what they find,” Copley said. “They will be collecting more samples, and we hope they will also be able to measure the temperature of the vents directly, which we could not do with our underwater vehicle.” 

Diving 

On 9 January, Jason made its first dive of the expedition to the 1.4-mile-deep Von Damm site. As well as filming and photographing the site, the vehicle also collected samples of rock from the Von Damm vent and picked up  

five tube worms, a clam and a sea cucumber and placed them in a tub on the front of the vehicle called the bio box. 

The next target was the Piccard thermal vent site, about an hour away on the Atlantis, where Jason made its second dive - a three-hour, three-mile deep journey. 

“The images from Piccard were breathtaking, with black smokers sending a whirlwind of mineral-rich fluid into the dark water. Everyone in the van was mesmerised by the images on the monitors, even if they had seen hydrothermal vents many times before,” wrote Julia DeMarines, a blogger and scientist on board the Atlantis, who is posting regular updates on the expedition, which is officially known as the “OASES 2012”. 

On that dive, via the video sent directly from Jason to the control station on board the ship, the scientists saw what they described as “strange yelloworange and white mats — what looked like fur on rocks was actually strings of microbes!” 

Jason has nine cameras, including two high-definition video cameras, and weighs more than 8,000 pounds. It’s about the size of a small Mini Cooper. It is tethered to another vehicle called Medea, which hangs 155 feet above it, and both vehicles descend at a rate of about 100 feet a minute. 

DeMarines explained that it takes six people to operate Jason, working in a control station called a Remote Operated Vehicle, or ROV, van, which is a converted cargo container that can be moved from ship to ship when necessary. 

The pilot controls Jason’s arms through a joystick replica of the vehicle’s actual arms.  

The expedition, which is being funded by the National Science Foundation and by NASA, is at the Mid-Cayman Rise, which lies in the middle of the Cayman Trough, also known as the Cayman Trench.  

In the middle of the Cayman Trough, which runs east to west, is the Mid-Cayman Spreading Centre — approximately 68 miles long and spreading apart at an ultra-slow rate of less than an inch per year. 

Until recent years, ultra-slow ridge systems were almost completely unexplored because of an early hypothesis that their slow spreading rates would make hydrothermal activity rare or absent. That theory has now, quite literally, been blown out of the water.