Chemicals from ancient sponges and sea bacteria hold the promise of powerful arthritis salves and cancer fighters, marine scientists say.

That's not all: An absorbent chemical in oyster shells could keep diapers drier or help clean up oil spills, researchers told the nation's biotechnology industry this week.Yet, they said, manufacturers are largely ignoring the ocean's repository.

"You have a whole sea of microbes whose potential is unexplored," said Linda Kupfer of the National Sea Grant, which gathered marine scientists to describe new research on ocean compounds, mostly medicines, that they believe biotech companies could bring to market.

The majority of drugs come from land discoveries such as soil microbes that have yielded dozens of antibiotics, herbs and tree bark-derived cancer drugs and pain-killers.

But with discoveries of novel drugs dwindling, the land is about tapped out, said William Fenical of California's Scripps Institution of Oceanography.

Millions of years of evolution gave ocean animals and microbes chemical defenses to survive predators and disease, said Shirley Pompani of Florida's Harbor Branch Oceanographic Institute. A sponge killing a parasite's rapidly growing cells is the same principle as killing human cancer cells, she explained.

"There are over 6,000 species of sponges alone, all with unique chemical compounds," she said.

Among the new finds:

-Bryostatin, made from moss-like animals that live on pier pilings, just became the first marine anticancer product to enter Phase II testing as a possible therapy for deadly melanoma. Although it's owned by Bristol-Myers Squibb, the National Cancer Institute is paying for all testing.

"It's still early," cautioned NCI's Dr. Anthony Murgo. But "we're interested in novel agents. It seemed to have anti-cancer activity that's somewhat different" than other drugs.

-Two rare marine molecules completely block a serious arthritis inflammation, said pharmacologist Robert Jacobs of the Uni-ver-sity of California, Santa Barbara. The molecules could help develop an alternative to steroid therapy because they "virtually wipe out" the cell process that swells joints, he said.

-Cone snails emit toxins that paralyze and kill prey, a neuromuscular block that could help epilepsy, Pompani said.

-Scripps just discovered a seaweed fungus chemical named halimide that killed drug-resistant cancer cells in test-tube studies. Another Scripps fungal find, halovir, is a never-before-seen type of antiviral that appears to kill herpes.

Money to research ocean chemicals is severely lacking, Fenical said. Most large drug makers ignore the resource, he said, but some biotech companies are starting to license promising compounds from taxpayer-funded scientists. "We virtually give these things away," he said.

The federally funded National Sea Grant, which promotes academic-industry research partnerships, funds $8 million a year in marine biotechnology programs. The NCI spends about that much screening potentially promising marine compounds.

One reason companies hesitate is that some sea compounds are too complex for laboratories to produce, Kupfer explained. "Their question is, `How are you going to get enough to supply a clinical trial?"

So researchers are developing ways to grow ocean compounds much as today's drug ingredients are produced and are studying just how these chemicals work so synthetic copies can be made.

Consumers shouldn't confuse this research with popular claims that shark cartilage will cure cancer, Fenical warned. "There's just no evidence that shark cartilage has any effect in cancer whatsoever," he said.

But the field goes beyond medicine: Those super-absorbent oyster shells show ocean compounds can lead to bioengineered products.