What promises to be one of science's strangest post-mortem examinations is under way at the Smithsonian Institution on a creature so rare it was seen by man for the first time less than a year ago.

The creature is a tube worm, 18 inches or longer, recovered by scientists from Pacific waters a mile-and-a-half deep near the Galapagos Islands off the coast of Ecuador. The worm has no mouth, no gut and no anus. It appears to have no means of breathing, feeding and digesting. Just as strange, the worm was found flourishing in water saturday with hydrogen sulfide, which is poisonous to almost all living things.

"I don't pretend to understand how this creature gets along," said Dr. Meredith Jones of the Smithsonian's Museum of Natural History, where the first microscopic analysis of the tube worm has begun. "All I know is that it is a very bizarre creature."

"There are no openings anywhere that we can see over the body length of the tube worm," said Jones, who now has seven of the dead creatures in his laboratory for analysis. "And some of these worms are quite large, having grown to a length of three feet."

The worms are called "tube worms" because they secrete a tube-like shell in which they live. They were first seen by scientists from Woods Hole Oceanographic Institution, massachusetts Institute of Technology, Oregon State University and the U.S. Geological Survey who traveled in a research submarine to the Pacific floor looking for vents discharging hot water from the bowels of the earth.

The scientists found the vetns, which were pumping water as hot as 63 degrees Fahrenheit into a surrounding ocean whose temperature was just above freezing. Projecting up from crevices all along the vents were hundreds of the blue-colored tube worms.

There was almost no oxygen around the vents. The water near by was charged with hydrogen sulfide converted from sulfates precipitated from minerals in the water by the heat of the vents and the pressure at that depth.

Saying he can only theorize on how the warms live, Jones speculates that bacteria in the water are metabolizing hydrogen sulfide and nourishing larger life forms like the worms. Some sea and earth worms do feed on bacteria, so his speculation is not unlikely.

Jones has cut up the first of the seven speciments into 20 tissue samples for microscope analysis. The first sample he'll look at is what appears to be the worm's head. At least, it's the end of the warm that sticks out of the tube and appears to have tiny spines or feathers that could serve for breathing and feeding.