A spider crab decided that the seismometer dropped by scientists would be its new home, and that’s when the battle began.
Thompson is the name of a research vessel drifting in the middle of the ocean. However, on this ship, you will rarely hear the sounds of the sea. Almost all the time, you are surrounded by the noise of engines, exhaust blowers, climate control systems, and the sounds of winches…
And on this ship, hundreds of kilometers away from land, scientific rescue operations never pause for a moment. Every day, 24 hours a day, everyone is continuously busy preparing, deploying, and recovering geological sensors from the ocean floor. They are trying to uncover complex questions about what causes volcanic activity – specifically, Axial Seamount, located about 400 kilometers west of Cannon Beach, Oregon.
But it was during this seemingly dull journey that researchers aboard the Thompson had the opportunity to witness a drama unfolding beneath the ocean waves. It is the story of man versus nature in a consuming battle on the peak of the most active volcano in the Pacific Northwest.
This is a story you might call “The Battle Between the Spider Crab and the Seismometer”.
The spider crab wanting to nest in the seismometer.
On a day in late June, researchers were operating a ROV – a remotely operated vehicle – named Jason, moving along the ocean floor. This machine has titanium arms with “fingers” that allow it to pick up objects from the seabed, move sensors, and even play the violin if given the chance. Simply put, it is a rather impressive and flexible robotic arm.
“It looks easy but is actually very difficult. You have to maneuver the vehicle just right. Then use the arm to perform some really intricate tasks,” said Bill Chadwick, a volcanologist from Oregon State University and the chief scientist on the vessel.
ROV Jason and its arms are controlled by a technician who sits in a control room inside a container on deck. People often jokingly refer to this space as “the truck.” It’s a dark and cold truck. Video feeds from Jason’s cameras cover one wall of the room, displaying parts of the ocean floor as Jason glides over them – lava flows, columns, cliffs, hydrothermal vents – some of which no human has ever seen before.
That day, the research team had just deployed a specialized seismometer, designed to study things like the shape of the magma chamber beneath the volcano. Engineer Ted Koczynski mentioned that the seismometer is highly sensitive to vibrations, and they needed a plastic dome the size of a car above it for protection.
Koczynski was not on the ship but was working at the Lamont-Doherty Earth Observatory in New York. He stated, “The whole idea of the shield is to prevent any flow from entering and affecting the seismometer.”
Jason’s task was to lift the dome off the ocean floor with its titanium claws and place it above the seismometer. A group of researchers sat in the truck behind the technician to watch Jason at work.
As the ROV was about to place the dome over the device, everyone saw it.
Expedition leader Akel Kevis-Stirling preparing to deploy the remotely operated vehicle Jason to explore Axial Seamount, a submarine volcano located about 400 km off the Oregon coast.
As Jason turned away, a large orange spider crab – with a body length of about two meters – crawled into the device and positioned itself atop the seismometer.
“I hadn’t accounted for the crab in my plans,” Bill Chadwick said, bewildered, knowing it would pose a problem.
A seismometer designed to respond to light currents would certainly be sensitive enough to detect the gentle taps of the crab’s tiny feet.
After some strategic discussions, a campaign to confront and handle the crab began.
Since the crab was too far inside the sensor casing, there were concerns that Jason’s claws could damage the equipment. Therefore, they decided to try Jason’s vacuum hose, aptly named “Slurp.”
The technician controlling Jason, Tito Collasius, was excited about this challenging and unprecedented task. He maneuvered the machine’s claw to bring the vacuum hose out. “This is for you,” he said as he moved it towards the crab.
“We’re coming. This is your last warning,” Chadwick added as he stood next to Collasius.
But the crab seemed to have seen or somehow sensed its impending doom. It began to scuttle away.
Then, seemingly wanting to prove its bravery, the spider crab stopped.
“Its name will be Moriarty,” Collasius said, naming the crab after the villain from the Sherlock Holmes series.
It was at this moment that the battle between the claws began. In a contest between “claws” of titanium and the crab’s pincers, Jason gained the upper hand. Cheers erupted inside the truck as the titanium claw gripped and slowly pulled the crab out.
“Finally, they caught it by the leg and carried it away. It was quite funny,” recalled Kelly Chadwick, a data recorder on duty at the time.
The technician controlling Jason moved the crab about 20 meters away from the seismometer and then released it. The crab immediately scurried off and disappeared.
ROV Jason pulling the spider crab from its hiding place atop the seismometer.
The story of the spider crab and the seismometer spread throughout the ship, delighting everyone. Clearly, when you are stuck on a vessel in the middle of the ocean, this is the most entertaining diversion.
It seemed like a perfect conclusion to the story. But as time went on, strange things began to happen beneath the waves.
First, one of Jason’s thrusters malfunctioned, causing it to move only sideways on the ocean floor. This made Chadwick speculate and worry.
“We had to remove the crab from one of our instruments. Now, one of Jason’s thrusters is malfunctioning, so now it’s moving around like a crab. I think the crabs have gained a point, it’s 1-1, the score is even,” he said.
However, the tie did not last long. As scientists were pulling up the seismometer and shield to check the collected data, they discovered that the shield had mysteriously disappeared. They saw it leave the ocean floor when Jason secured a buoy to it, but when Pete Liljegren, another engineer on board, retrieved the buoy at the surface, the shield was gone.
Of course, on a ship full of scientists and engineers, not everyone is easily swayed by such surreal speculations. But one theory persisted, suggesting that the loss of the shield was related to the crab from the previous day, and it could even be a coordinated effort by a swarm of crabs.
However, the shield was quite large, and crabs would not be strong enough to steal it. Scientists shifted their suspicion to seals, an intelligent species. For Chadwick, he began to worry about the equipment scattered on the ocean floor above his volcano.
“At some point, there’s a crab waiting there… to mock us,” he said.
