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In a few weeks, Juneau scientist Tom Shirley will be taking a tiny submarine and diving as deep as 15,000 feet below the surface of the Gulf of Alaska, part of an ocean exploration project studying a range of undersea mountains and the strange life forms that inhabit them.

"It's Jacques Cousteau science - exploring new places in the world's oceans," Shirley said.

"These seamounts are enormous," Shirley said. "They're almost an island chain, but they're subsurface."

Shirley and co-investigator Brad Stevens of the National Marine Fisheries Service in Kodiak will look at the deep-sea habitats and communities of life that surround these seamounts. Both have studied king crabs and their deep-water relatives and are hoping to learn more about the brown or golden king crab in particular.

Other scientists, from Woods Hole Oceanographic Institute, the University of California at Santa Barbara and Oregon State University, are studying deep-sea soft corals and the geologic history of the seamounts. Two journalists with National Geographic and some graduate and undergraduate students also will be aboard the Atlantis.

The scientists will use Alvin, a tiny submarine capable of descending nearly three miles beneath the ocean's surface, where creatures live by different rules than the rest of life on Earth. Some are crabs, adapted for life in near-freezing, pitch-dark water with little oxygen.

Other creatures surround deep-sea thermal vents associated with many of the seamounts, vents that spew hot, mineral-rich water into the depths. These creatures are methanogens, life forms that use methane, not photosynthesis and oxygen, as the basis for life. They form the bottom of a food web that also supports crabs and fish.

Among other studies, Stevens and Shirley will be collecting muscle tissue from the crabs, part of the Fairbanks researcher's project to determine if some deep sea crabs are living on these methane-based food webs.

"There are some pretty bizarre creatures - gutless bivalves and gutless seaworms that have symbiotic bacteria living in them that use methane for energy and pass some energy along to their hosts," Shirley said.

Undersea volcanic activity fuels the vents and is also responsible for the formation of the seamounts. These submerged mountains, some of which rise almost 15,000 feet off the ocean floor, are extinct volcanos. They formed off the coast of Washington over a geologic phenomena called the Cobb Hotspot, a place where magma from the Earth's mantle upwells onto the ocean floor. As these volcanos formed, movement of plate tectonics carried them in a long arc northward.

Two parallel mountain ranges several hundred miles long stretch from the Cobb Hotspot toward Kodiak Island. Some of the seamounts in the range have been explored, others will be explored on the coming trip.

These seamounts rise from the fairly level plain of the ocean floor. They generate turbulence, upwelling and currents that can create productive habitat for crabs and marine life.

Crabs don't have air bladders, and so can be brought up from great depths without pressure changes destroying them. Alvin has arms that can grab samples, and these arms have been modified so Shirley and Stevens can catch crabs without crushing them. The creatures are vulnerable to exposure to light and temperature changes, and quickly will be transferred to suitable containers so they can be kept alive. They will be offloaded at Stevens' lab in Kodiak a couple of weeks into the trip.

More information on the expedition is available online at the NOAA Web site, oceanexplorer.noaa.gov. Look for links to exploring Alaska's seamounts.

To learn more about what it's like to dive in Alvin, go to http://www.whoi.edu/home/about/whatsnew_trading_alvindive.html for a guided tour.

Riley Woodford can be reached at rileyw@juneauempire.com.