GRANTSVILLE -- You never know what you'll find when you go turning over rocks.

Last week, in the cold, clear Casselman River near here, Ed Thompson and Dan Feller pried a sandstone slab off the bottom and spotted what they were looking for: a hellbender.

"There she is," said Feller, as Thompson scooped up a big, grotesque-looking creature with tiny eyes, wrinkled skin and a name worthy of a Stephen King novel.

Hellbenders are North America's largest salamanders, with ancestors that used to hide from dinosaurs. They can grow to 2 1/2 feet in length and weigh up to five pounds. Found in fast-flowing streams from New York to Georgia, they hide under submerged rocks by day and emerge at night to feed on crawfish, insects and small fish.

They are so seldom seen in Maryland that they have been classified by the state as endangered. Thompson and Feller, biologists with the state Department of Natural Resources, are searching the only two places where hellbenders are believed to remain -- the shallow Casselman and Youghiogheny rivers in Garrett County.

"We're trying to find out if hellbenders are going to be able to stay here, or if we need to help them," said Thompson, who specializes in tracking rare plants and animals in Western Maryland.

About the only thing the biologists know about hellbenders is that they are hard to come by. Searching for them is a Sisyphean task: prying one heavy rock after another from the river bottom to peer beneath it -- usually in vain -- then carefully lowering it back into place. Together, the two hoist 200 rocks a day, some weighing more than either of the men.

"It's a lot of work to catch a hellbender," said Thompson, 45. To save their backs, they use a "log peavey," a hooked lumberjacks' tool that can grip one edge of a slab so it can be levered up.

Why bother? Because hellbenders could be biological indicators of a stream's environmental health. Here and elsewhere, they seem to live only in clear, fast-flowing waters favored by trout, a popular sport fish that also is sensitive to pollution.

Feller, 33, offers a more philosophical reason for caring about hellbenders: "They've been here millions of years, and we think they deserve to stay."

Cryptobranchus alleganiensis, as hellbenders are known scientifically, are one of three species of giant salamanders. The other two, found in China and Japan, have been known to grow to nearly six feet in length.

Hellbenders are different from most other amphibians in that they spend their entire lives in water. Though hatched with gills, when mature they "breathe" through the fleshy folds of their skin. They are long-lived -- up to 55 years, in one case -- but also slow to mature.

"They're an ugly-looking thing," said Mark W. Horchler, who farms along the Casselman, where Feller and Thompson found the hellbender last week. Horchler, 75, recalls catching hellbenders in his youth when he fished the river at night.

"We'd toss them right back in," he said.

Native Americans might not have been so choosy. Feller said hellbender skeletons have been unearthed in Indian village middens, or trash dumps. Fossils of an extinct form of hellbender have been found in the Potomac River watershed.

Mysterious name

No one seems to know how hellbenders got such a nasty name.

Some think it stems from the serpent-like way they move through the water, waving their oar-like tails.

Others think they got labeled by fishermen who were startled -- and revolted -- to find them on their hooks instead of fish.

"It does bend and twist, so maybe that's where bender comes from," said biologist Ed Gates of University of Maryland's Appalachian Environmental Laboratory in Frostburg. "It might look like a creature from hell."

Despite their fearsome name, hellbenders are shy and docile. They have teeth, and their bites can be painful, as Thompson's son once discovered. But their chief means of defense seem to be their size and a whitish slime they ooze through their skin when handled.

"I tasted hellbender slime," said Thompson. "I touched it to my tongue, and it was so bitter it had to be poison."

The specimen that the two biologists caught last week is an old friend, found in the same spot over several years, and at 19 inches long it is one of the largest documented in Maryland.

"She's pretty, as hellbenders go," said Feller. She weighs 700 grams -- a little more than 1 1/2 pounds. That's 40 grams lighter than when she was checked last year, leading the researchers to speculate that she was carrying eggs then.

'Population in trouble'

But hellbenders' reproductive activities and early lives remain a mystery. Feller and Thompson haven't found many eggs in either river, and they have never seen young larvae.

"We really think the population is in trouble in the Casselman," Thompson said. Since beginning to canvass the river last year, the two biologists have caught a total of 23 hellbenders, most in a mile-long stretch of the river near the Pennsylvania line. They were common upriver near the U.S. 40 bridge but can no longer be found. They also have vanished from the lower Susquehanna River in Harford County.

Thompson, who has studied hellbenders off and on since the early 1980s, said scientists don't know if the population in Maryland is still declining. Silt from erosion and the removal of trees that had shaded streams might disrupt the creatures' habitat, as is evident in the stretch of the Casselman where the hellbender turned up last week. Fields were plowed almost to the water's edge, and cattle were grazing beside, and in, a creek tributary.

Some scientists have suggested that the state should protect the hellbenders' habitat, but any regulations or laws limiting property rights would be a tough sell, Thompson acknowledged. And while others have suggested transplanting the creatures to other streams to help the population rebound, the biologists are not sure any would survive such a disruption.

"They're awesome," said Feller, adding, "They have no known enemies except humans, when we foul the water."

Pub Date: 9/17/98