The Worms Like It Hot

The sulfide worms that live on deep-sea thermal vents are some of the most heat-tolerant animals on Earth, although the maximum temperatures they can withstand aren't exactly off the charts, researchers report.

These polychaete worms, formally known as Paralvinella sulfincola, have bushy red gills and long, stalk-like bodies, and live on rocks where extremely hot and cold waters mix together. Researchers have been debating how much heat these animals can take, since some evidence has suggested that they can live at extremely high temperatures. But, the mitochondria found in all animal cells may not function at temperatures above 55 degrees Celsius.

Peter Girguis and Raymond Lee built an aquarium that replicated the high pressures and quickly changing temperatures of the vent environment, and they found that the sulfide worms moved into zones that were 45-50 degrees Celsius. Furthermore, the worms chose to stay there for more than seven hours.

A preference for such high temperatures has never been observed before, according to the authors of this "Brevium" article. Although the worms could briefly tolerate slightly higher temperatures, they never entered zones with temperatures above 60 degrees Celsius. Thus, P. sulfincola actually prefers conditions that are unusually steamy but not so extreme as to require a new explanation for how their mitochondria work.

This research can be found in the 14 April 2006 issue of the journal Science.

Kathy Wren

14 April 2006