Tubeworms at the cold and calm hydrocarbon-seep sites in the Gulf of Mexico have surprisingly long life spans, especially compared to their cousins living at the hot and dynamic hydrothermal vents, according to a paper published in the 3 February 2000 issue of the journal Nature by a Penn State research team.
"The hydrocarbon-seep tubeworms we studied take from 170 to 250 years to grow two meters long, while hydrothermal-vent tubeworms grow well over a meter in just one year," says graduate assistant Derk C. Bergquist, an author of the research paper along with Frederick M. Williams, associate professor emeritus of biology, and Charles Fisher, professor of biology.
"The hot hydrothermal vents are a much more vigorous, variable, and ephemeral environment than the cold hydrocarbon seeps," Fisher says. Both the seeps and vents are regions on the ocean floor where fluids rising from the Earth's crust are breaking through and mixing with the seawater. But hydrothermal vents have a wide range of shifting environments including "black-smoker" chimneys belching out material as hot as 400 degrees Celsius, whereas seeps release the hydrocarbon fluid slowly and dependably over a long period of time at seawater temperatures.
"The chemical content of the fluid is similar but it's cooled down and calmed down a lot at the seeps," Bergquist explains. Tubeworms live on the sulfide and other nutrients in the fluids at both the seeps and the vents, but they grow at much different rates in these two very different environments, according to the researchers.
The scientists say the tubeworms they studied at the cold seeps are the
most long-lived noncolonial animals without backbones currently known.
"The tissues of colonial animals like coral and anemone are continually
recycled by the community, so it is tough to say what a single individual
is in a colonial animal," Bergquist explains. "Entire colonies can have
life spans over 1,000 years, but no individual poly
Contact: Barbara K. Kennedy