A 15-foot megamouth shark, a species so rare that marine biologists have never seen one alive, has been hauled into Dana Point Harbor, and scientists hoped it would not die before they could study it.

The shark appeared to be swimming and in good condition Sunday, and scientists said they hoped it would stay alive at least until Monday morning, when they could film it for study. Scientists said they would have to set it free because there is no facility capable of holding it.The giant shark, which lives more than 600 feet below the surface in the blackness of the middle ocean, was caught Sunday in a gill net by a commercial fishermen and hauled to the port north of San Diego by a rope tied around its tail.

"This is like an alien coming out of the depths," said Dennis Kelly, a marine biologist at Orange Coast College. "It's one in a million. We didn't even know that they existed until they caught the one in Hawaii in 1976."

That had been the only megamouth brought to shore alive, but before marine biologists could arrive to study it, the animal died after swallowing an anchor at a Navy base.

A spokesman at Sea World said so little is known about the species that even the experts would not know how to keep it alive - what to feed it, what kind of lighting it needs.