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Many people think of corals as underwater plants, but they are animals.

"Corals are in the same group of animals as sea anemones and jellyfish," said Bob Stone, a fisheries research biologist with the National Marine Fisheries Service. Along with his colleagues at the Auke Bay Laboratory, he has been at the forefront of Alaska's coral research.

Cold-water corals differ from their warm-water cousins, which have symbiotic algae living within the coral polyp's tissue that thrive with sunlight. Cold water corals need no light to grow and feed off ocean nutrients filtered down through their colonies. Many of these coral polyps are small tubular animals that use tentacles to reach out and grab their food, while having a base that attaches to a hard surface.

"They live an incredibly long time, and if you think about it, where these animals live it's an incredibly stable environment," said Stone. "The water may vary a few degrees every year, but that's about it."

Stone said the cold water corals have rings, much like those of trees, which he believes may coincide with the age of the animals. He is still conducting tests to verify that, but said he has counted more than 500 rings in one sample and believes some corals may be older than 1,000 years. Some coral around the world are up to 1,700 years old, scientists say.

Jon Heifetz, another research biologist at the Auke Bay Laboratory, said the research of deep-sea cold water corals is just beginning and there are still many questions about them.

"We really don't know the big picture," said Heifetz. "We just started the research and there are lots of unknowns."

Heifetz said the Aleutian chain "seems to have the highest diversity and abundance of deep-sea coral" in the world.

"The habitat itself, just the corals around, are really unique. We don't think there is anything really like it in the world," he said.

Corals grow at an incredibly slow rate, estimated at about one centimeter a year. They can thrive at extreme depths. Stone has spent two weeks each of the past two summers researching Alaska corals with a two-man submersible at depths reaching about 350 meters. In 2004, researchers will bring an unmanned submersible to the Aleutian Islands that can video the sea floor at a depth of 3,000 meters, Heifetz said.

Coral gardens have their own miniature ecosystems that provide habitat for dozens of species of sealife. Rockfish, perch, flatfish, mackerel, crab, shrimp, cod, pollock, sea stars, snails, and octopus are some of the sealife that have been observed around corals.

Stone said the lab's research was an effort to collect some samples, initiate a few simple life history studies, figure out how the corals reproduce and grow, and what their life span might be. In their exploratory effort the scientists have identified around 34 types of coral species in Alaska waters, including red tree coral and bubble gum coral, but they say there is still much more work to be done.

"I think that we could continue looking out there for a hundred more years and still find new stuff," said Stone. "We're just scratching the surface every time we go out."