Giant Tubeworms Probed for Clues to Survival

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The worms live at the interface of two worlds. The tip of the worm—a scarlet feathery plume—extends into the frigid seawater just a few degrees above freezing. The rest of the white tube stands in water heated to about 70 degrees Fahrenheit.

"It's like having a 40-degree temperature difference between your 'head' and 'feet,'" Kang says. "I don't know any animal that does this."

Poison versus Food

The chemical brews gushing out of the vents provide nutrients for deep-sea life. One ingredient of the vent fluid—hydrogen sulfide, or rotten-egg gas—is toxic to most land-based life. But poison for one creature is food for another.

The tubeworms derive all their nutrients from bacteria that live in their gut. The bacteria use hydrogen sulfide as an energy source to produce carbohydrates for the worm.

Kang suspects that the worm bridges two temperature zones because the bacteria in its gut require warmth while its red plume harvests nutrients in the cooler water above.

Kang's sensor is helping to determine the tubeworms' chemical environment.

"Chemistry is everything to these animals," Shank says. Chemistry affects where species live, and for how long. The tubeworms are undersea pioneers—the first to colonize new vent sites; they were followed by mussels and clams.

The vents continually switch on and off, often abruptly halting the supply of nutrients. "This creates boom-and-bust communities," Shank says.

When the vents stop flowing, all the animals die. To survive these cycles, tubeworm larvae must sense the location of new vents, settle down, grow fast, and reproduce.

That complicates life for the scientists, too. So their next goal is to build sensors that can be left on the seafloor for long periods.

"Continuous monitoring is necessary," Kang says. "Otherwise, we just get snapshots, and we miss the relationships between the chemistry in the area and the species that live there."

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