Dive 03: Giant Bedforms
Date: June 16, 2018
Location: Lat: 31.15821909°, Lon: -75.66093095°
Dive Depth Range:: 3,292 - 3,353 meters (10,800 - 11,001 feet)


Location of NOAA Ship Okeanos Explorer on June 16, 2018.

Location of NOAA Ship Okeanos Explorer on June 16, 2018. Download larger version (jpg, 579 KB).

3D view of the planned ROV track for Dive 03 shown as an orange line. The background represents the seafloor depth color-coded with slope in degrees. The warmer the color, the steeper the slope.

Three-dimensional view of the planned ROV track for Dive 03, shown as an orange line. The background represents the seafloor depth color-coded with slope in degrees; the warmer the color, the steeper the slope. Download larger version (jpg, 342 KB).

Dive 03: Who Will Back Off First?

Here comes a deepwater hermit crab (family Parapaguridae). Notice the very long legs with their elongate last segments – an adaption for moving across soft mud. Only the first two pair of walking legs actually serve in movement. The other two pair hang on to the covering of the soft abdomen.

In some species of parapagurids, a small hermit crab moves into a real gastropod shell. Later, an anemone (or in this case, a relative of sea anemones called a zoanthid) overgrows the shell and forms a snug shell-shaped covering. This "false shell" can sting and protect the crab from octopuses.

If the Deep Discoverer remotely operated vehicle stirred up the seafloor, the hermit crab may sense uncovered "goodies" such as worms or small clams and may be rushing over to snatch a meal.

Text contributed by Mary Wicksten, Texas A&M University.

Video courtesy of the NOAA Office of Ocean Exploration and Research, Windows to the Deep 2018. Download larger version (mp4, 20.0 MB).

Today was the third dive of the expedition at a site named "Giant Bedforms." This site was named based on the features consisting of giant undulating bedforms that extend across a large region of the southern flank of Blake Ridge. These features are aligned in rows similar to large ripples, with crest-to-crest wavelengths of hundreds of meters and heights of over 30 meters. Their asymmetry suggests formation by persistent southward-flowing bottom currents. They have never been explored with a remotely operated vehicle (ROV). This dive was a different habitat than the previous dives this expedition, so scientists expected to see different fauna during the dive.

ROV Deep Discoverer was on the seafloor from 14:14:11 - 18:45:28 UTC. This dive was dominated by a relatively high current. As expected, the seafloor consisted of very large bedforms comprised of soft sediment and no hard bottom. Starting around 3,338 meters (10,951 feet), the ROV traversed over one entire bedform and up a second one, over flat and featureless mud with occasional burrows and small mounds. The fauna included many stalked sponges (Hyellanema) and tunicates, glass sponges, Umbellula sea pens, anemones, holothurians including a swimming sea cucumber, Coryphenoides rattail fishes, tunicates, and amphipods making homes in the holes of the sediment. There were no true corals throughout the dive. The ROV collected a geological sample of a scoop of the soft sediment characteristic of this dive location as well as a tunicate (Pyuridae), which the science team could not identify. The dive concluded at 3,292 meters (about 10,800 feet). A more detailed overview of the dive will be provided at a later date in the dive summary. While this was a very deep dive at nearly 3,300 meters (over 10,000 feet) and was 200 nautical miles offshore, scientists still observed various marine debris along the seafloor.

Thanks to the telepresence capabilities of NOAA Ship Okeanos Explorer, this dive was streamed live to various locations, including to you at home. The South Carolina Aquarium tuned in to the live video feed for four hours today and had a total of 75 visitors stop by during the event. Through telepresence, you can continue to follow along live with us tomorrow for the fourth dive of the expedition at Blake Escarpment South.

Remotely operated vehicle (ROV) Deep Discoverer collects a geological sample of the seafloor sediment using the scoop tool. Collecting these samples allows scientists to learn more about geologic features in the region.

Remotely operated vehicle Deep Discoverer collects a geological sample of the seafloor sediment using the scoop tool. Collecting these samples allows scientists to learn more about geologic features in the region. Image courtesy of the NOAA Office of Ocean Exploration and Research, Windows to the Deep 2018. Download larger version (jpg, 939 KB).

During Dive 03 at Giant Bedforms of Blake Ridge, the ROV Deep Discoverer imaged these amphipods making a home in the pits in this sediment.

During Dive 03 at Giant Bedforms of Blake Ridge, ROV Deep Discoverer imaged these amphipods making a home in the pits in this sediment. Image courtesy of the NOAA Office of Ocean Exploration and Research, Windows to the Deep 2018. Download larger version (jpg, 2.8 MB).