Dr. Craig Cary, chief scientist, prepares to board the submersible Alvin.

On November 29, 2003, an international research team led by University of Delaware marine scientist Craig Cary will set sail from Manzanillo, Mexico, on the 23-day expedition "Extreme 2003: To the Depths of Discovery."

Their mission will be to explore biocomplexity — the complex interplay between living organisms and their environment — at super-hot hydrothermal vents over a mile deep on the Pacific Ocean floor.

The scientists will travel aboard the 274-foot research vessel Atlantis to their dive site in the Pacific and then descend to the vents in the famous deep-sea submersible Alvin. Both vessels are operated by the Woods Hole Oceanographic Institution.

The Pompeii worm pokes its head out of its sweltering tube home at the base of a hydrothermal vent. Photo courtesy of Dr. Richard A. Lutz and Andrew Reed, Rutgers University.

The researchers will study the vents and the strange organisms that inhabit them, including the Pompeii worm — Earth's most heat-tolerant animal, able to withstand temperatures up to 80°C (176°F).

Vents Teem with Unusual Life

The ocean's greatest depths once were believed to support only a few organisms. But in the past 25 years, intrepid explorers, diving to the seafloor in high-tech submersibles, have disproved that notion. They have discovered that a number of unusual creatures inhabit some areas of the deep sea — at underwater geysers called hydrothermal vents.

Here, over a mile beneath the ocean's surface, live dinner-plate-sized clams reeking of sulfur, towering tubeworms resembling giant lipsticks, ghost-white crabs prowling for prey, pinkish eel-like fish, and the microscopic bacteria that hold together this strange web of life.

Currently, scientists are exploring hydrothermal vent sites to learn more about this "extreme" environment and its unique community of organisms.

After all, vent dwellers thrive under some of the most demanding conditions on the planet. They live in a world of total darkness. They are constantly bathed in toxic chemicals that rocket out of the vents. And some vent organisms — tiny microbes — can survive water hotter than boiling!

Tubeworms (Riftia pachyptila) are the most dominant animals at the East Pacific Rise vent sites. They may grow to about 3 meters (8 ft) tall. They have no mouth, eyes, or stomach. They depend on bacteria living inside them for survival.

What's more, the atmospheric pressure exerted on these organisms from the weight of the vast ocean above is more than 250 times the pressure we feel on land.

Surf through our Web site and learn more about hydrothermal vents, the fascinating creatures that inhabit them, the technology that makes deep-sea research possible, and the discoveries that marine scientists are making. Let's dive in!