Feature Stories

Toasty Tubeworms

Tubeworms living at deep-sea hydrothermal vents seek out scorching temperatures.

Deep on the seafloor, the fluids that flow from hydrothermal vents can reach temperatures of more than 350°C (662°F)! Temperatures this high, or even close to this, are fatal for most forms of life (including you and me). However, a rich and diverse group of animals and microbes have adapted to make these deep-sea 'hot spots' their home.

Paralvinella tubeworms (orange) cluster near the base of an active chimney (center bottom) at the ASHES hydrothermal vent site at Axial Seamount, Juan de Fuca Ridge. The photo was taken by the ROPOS remotely-operated vehicle (ROV) in September 2003 at a depth of 1,547 meters.
Image credit: William Chadwick, Oregon State University & NOAA Vents Program.

Tubeworms are one of the most unique animals that live at vents, and they are known to be able to tolerate some of the hottest vent fluids. Just how hot do the tubeworms like their living space? That can be a tricky question to answer. Although the vent fluids can be very hot, the seawater that surrounds them (only a few centimeters away) can be as chilly as 2-3°C (35-37°F). Since most tubeworms live very close to where the hot fluids and cold seawater mix, it can be difficult to precisely measure the temperature at the exact location of the worms.

So how can scientists accurately determine what temperatures different species of tubeworms prefer? Recently, two scientists — Dr. Peter Girguis of Harvard University and Dr. Raymond Lee of Washington State University — attempted to answer this question by bringing some tubeworms from the deep-sea into the laboratory for some experiments.

Conducting an experiment with tubeworms is no easy task. In order for the animals to survive, you need to mimic the conditions of their natural environment. For tubeworms, this means not only re-creating high water temperatures, but also the incredibly high pressure these worms require from adapting to life beneath more than a mile and a half of water in the deep-sea.

To mimic the tubeworms' natural environment, Drs. Girguis and Lee developed a special high-pressure aquarium that allowed them to precisely control the water temperature. They adjusted the aquarium so that water at one end of the aquarium was cool (20°C, 68°F), while water at the other end was hot (61°C, 142°F). They then placed one species of tubeworm, Paralvinella sulfincola, in the middle of the aquarium and observed them to see whether they moved towards the hotter or cooler ends of the tank.

To their surprise, the scientists found that not only could the tubeworms survive at high temperatures, some actually preferred them! When the tubeworms were placed in the aquarium the worms gradually moved toward the hotter end of the tank and remained in water that was 40°-50°C (104°-122°F) through the end of the experiment. These results provide evidence that this tubeworm is one of the most heat-tolerant animals on the planet.

Dr. Pete Girguis of Harvard University prepares a high-pressure aquarium to test the temperature preference of the deep-sea tubeworm Paralvinella sulfincola.
Image credit: Dr. Pete Girguis, Harvard University

"Even after thirty years of research, hydrothermal vent organisms still manage to surprise us. Each time my group and I go to sea, we observe things we've never seen before, and discover more about how organisms have adapted to life in these extreme vent environments", remarked Dr. Gurguis. "It's really very exciting, and I wish everyone could have the chance to see these amazing ecosystems."

Why do these tubeworms prefer to live at such high temperatures? Scientists think that this might allow them to avoid competing with other animals for resources (such as living space, food, or protection from predators), since most other organisms cannot tolerate living at such high temperatures.

So let's toast to the amazing tubeworms - may they continue to fan the flames of our imaginations as they beat the heat with their cool lifestyles.