A 6-inch shrimp flaps past. Sneaky white crabs steal bites off tube-worm tops, and white fish drape their ribbony length over whatever will support them. But at other vents, the party is over. Pale tubes, vacated by their red-plumed residents, lie on the lava, and a few ghostly crabs pass through, trucking off to somewhere more promising. The primary culprit is the cooling magma and loss of heat that comes with it.
Heat comes and goes with the volcanic dyspepsia under the ridge.
But this phenomenon has accomplices. One is vent-water chemistry, which changes as the circulating water scours different chemicals from the rock plumbing. The other accomplice is the gas content of the water. That's what brings University of Washington marine chemists Marvin Lilley and Eric Olson out to Nine North. When Nine North erupted in 1991, it blew up more than tube worms.