A few years ago, the NOAA ship Okeanos Explorer was on the third and final leg of 57-day expedition in the Gulf of Mexico. Its remotely operated vehicle, or ROV, called Little Hercules was deployed in the water approaching an unidentified shipwreck.
The Okeanos was streaming its mission live, and I watched it from the comfort of my home office in the middle of Texas, though I felt like I was in NASA’s control center during a moon landing. We explore our own oceans as if we were aliens, relying on high-tech gear to electronically reach down into this strange and foreign world.
The feed on my computer screen was divided into quadrants. The top left was from the ROV’s video camera. The quality of the image was outstanding, better than the video camera I used for my kids’ birthday parties. A second quadrant showed the control room on the ship, two rows of scientists plugged into headphones and staring at screens in a darkened room. They were talking in moderated voices saying official-sounding things like “Roger, that” and “Vertical lift, please.
The lead voice was the Chief Scientist Jamie Austin, senior research scientist at The University of Texas at Austin. Biologist Erin Becker, a post doc at Penn State, joined her. Erin’s job was to explain what life forms we are looking at.
Another feed was from the camera perched atop the ROV that the ROV pilot used to navigate. There was also real-time sonar showing the outline of the wreck, sound waves converted to rainbow-edged shapes.
The scientists had followed clues from a sonar image that suggested there was a wreck in this location. They believed that was about 200 feet long. The depth was about a quarter mile below the ocean’s surface.
As the pilot guided the ROV toward the wreck, a shadow resolved into wood and cables encrusted with biology. Amid the mostly khaki-colored fuzz, an orange squat lobster fiercely waved its claws above its head. Venus fly-trap sea anemones with orange mouths agape dotted the debris as did an unidentified species of albino anemone, but the scientists commented that the overgrowth on this edge of the ship was not extensive.
The wreck was just a few miles east of the mouth of the Mississippi River where that massive river dumps sediment into the bottom of the Gulf. The scientists discussed the possibility that this wreck had been covered in sediments from an avalanche in the past, and had only recently been uncovered and made available for settlement by marine life. A few pale hake, honestly not the noblest looking fish, flitted in and out of the edge of the ROV’s spotlight, sweeping the fine mud floor with their long white whiskers.
“Lasers, please.” Came a voice from the control center. Two red dots appeared on the video from the ROV. The beams were separated by 3 inches and gave a context for scale. Many of the Venus-fly trap anemones stretched wider than the dots.
Thousands of pinpricks of light reflected around the feed from the ROV like moths around a porchlight. These were the tiny and unspecified zooplankton: crustaceans like amphipods and copepods, swimming snails, little fish.
Other bits fell and swooped gracefully without direction. This was the marine snow that engulfs the bottom of the sea in a continuous blizzard. Marine snow is the remains of creatures that have died in the surface waters. On the journey to the sea bottom, bacteria decompose the organic matter, eating away at the meatier sections and leaving a scaffolding of the tougher material. By the time the debris reaches the sea floor, it really is snow-flake-like, fluffy and light. Marine snow is one of the key ways the ocean pulls carbon from the atmosphere and sequesters it at the bottom of the sea, helping solve our climate change problems.
I squinted at the screen hoping to see the pulse of a jellyfish. It was possible that many of the tiny specks of light were hydromedusae, the most abundant and most poorly known of the jellyfish.
The ROV moved to an upper end of the ship. Erin noted that there was more biology on this end. The current was faster here and these filter feeders had a better shot at snagging a passing shrimp. The animals were all jellyfish-cousins: dandelion-yellow coral, frilly white anemones, ochre sea fans. Living above the seafloor sediments, their fine tentacles were less likely to become clogged with silt than on the lower side of the ship. I wondered how many jellyfish polyps lived amid this cnidarian meadow.
From control, “We think we see a salp.”
From Erin, “Confirmation. That’s a salp.”
I saw the animal they were talking about. Its barrel-shaped body was translucent but for what looked like glowing orange highlighter pen lodged in its center. And, from the silty gloom, a second salp zoomed toward the ROV’s light.
Now, I saw what I thought was a single jellyfish. A semicircular bell, four thin zig-zagged tentacles below – but it pumped out of view very quickly. Did its primitive eyes detect the light? Did its nervous system fire a danger signal?
More and more salps appeared. Some sported a brick-colored smear rather than a highlighter in the center of the barrel. Were they males and females? Or different species? They moved so much like fish, I was amazed. Several were infested with parasitic crustaceans called amphipods. One spun in circles, having been incapacitated by crab-like freeloaders.
I thought I saw a ctenophore, a glimmering several lobed creature, cruise by. And then a siphonophore, a connected row of lights, undulating in concert, but it too escaped quickly from the ROV’s view.
A pyrosome drifted into view. It looked more like an inert short broomstick than something alive. But it is a cylinder of tiny individual jellyfish stuck together in the shape of a tube. Compared to the speedy salps it hardly moved at all.
The graceful siphonophore returned. And then glided offscreen.
The quality of the video was outstanding and the splendor of the animals astonishing. Within a half an hour, I had seen almost every form of gelatinous creature that exists in the sea.
I watched the feed all day, keeping it live in the background while I tried to do my work. The archeologists on the line debated the origin of the ship, which the figured was built in the late 19th century. They praised the robust beams and siding. They noticed iron oxides that might have been anti-fouling paint. The expedition’s log later reported that the ship was the most well-preserved wooden shipwreck ever discovered in the Gulf of Mexico.
For me, the feed was a great discovery too, one that no one, not even the ship’s biologist, commented on during the dive. Atop the wreckage of the ship, corals and anemones were as common as grass. Pyrosomes were like tree roots. The jellies and siphonophores like insects and the salps like birds. We are told that the ocean makes up two-thirds of our planet, and that’s the way it looks on a flat map. But it’s not true at all. In three dimensions, the deep sea is 93 percent of the living space on earth. In that massive volume, the gelatinous creatures are everywhere.
The trees and bugs and the birds we see every day live on just a thin skin of dry land. Though familiar to us, they are the rarity. The most common creatures on earth are those we don’t know at all.
All images in this blog are from the highlights video from the NOAA Okeanos Explorer Program. It’s incredible footage, but the pyrosomes, siphonophores, and jellies didn’t make the cut.