GULF SHORES, Ala. — Dolphins and sharks are showing up in surprisingly shallow water off Florida beaches, like forest animals fleeing a fire. Mullets, crabs, rays and small fish congregate by the thousands off an Alabama pier. Birds covered in oil are crawling deep into marshes, never to be seen again.

Marine scientists studying the effects of the BP disaster are seeing some strange phenomena.

Fish and other wildlife seem to be fleeing the oil out in the Gulf and clustering in cleaner waters along the coast in a trend that some researchers see as a potentially troubling sign.

The animals' presence close to shore means their usual habitat is badly polluted, and the crowding could result in mass die-offs as fish run out of oxygen. Also, the animals could easily be devoured by predators.

"A parallel would be: Why are the wildlife running to the edge of a forest on fire? There will be a lot of fish, sharks, turtles trying to get out of this water they detect is not suitable," said Larry Crowder, a Duke University marine biologist.

The nearly two-month-old spill has created an environmental catastrophe unparalleled in U.S. history as tens of millions of gallons of oil have spewed into the Gulf of Mexico ecosystem. Scientists are seeing some unusual things as they try to understand the effects on thousands of species of marine life.