The carcass of a six-foot American alligator is shown protruding from the mid-section of a 13-foot Burmese python.

MIAMI, Fla. — Alligators have clashed with nonnative pythons before in Everglades National Park. But when a 6-foot gator tangled with a 13-foot python recently, the result wasn't pretty.

The snake apparently tried to swallow the gator whole — and then exploded. Scientists stumbled upon the gory remains last week.

The species have battled with increasing frequency — scientists have documented four encounters in the last three years. The encroachment of Burmese pythons into the Everglades could threaten an $8 billion restoration project and endanger smaller species, said Frank Mazzotti, a University of Florida wildlife professor.

The gators have had to share their territory with a python population that has swelled over the past 20 years after owners dropped off pythons they no longer wanted in the Everglades. The Asian snakes have thrived in the wet, hot climate.

"Encounters like that are almost never seen in the wild. ... And we here are, it's happened for the fourth time," Mazzotti said. In the other cases, the alligator won or the battle was an apparent draw.

"They were probably evenly matched in size," Mazzotti said of the latest battle. "If the python got a good grip on the alligator before the alligator got a good grip on him, he could win."

While the gator may have been injured before the battle began — wounds were found on it that apparently were not caused by python bites — Mazzotti believes it was alive when the battle began. And it may have clawed at the python's stomach as the snake tried to digest it, leading to the blow up.

The python was found with the gator's hindquarters protruding from its midsection. Its stomach still surrounded the alligator's head, shoulders, and forelimbs. The remains were discovered and photographed Sept. 26 by helicopter pilot and wildlife researcher Michael Barron.

The incident has alerted biologists to new potential dangers from Burmese pythons in the Everglades.

"Clearly, if they can kill an alligator they can kill other species," Mazzotti said. "There had been some hope that alligators can control Burmese pythons. ... This indicates to me it's going to be an even draw. Sometimes alligators are going to win and sometimes the python will win.

"It means nothing in the Everglades is safe from pythons, a top down predator," Mazzotti said.

Not only can the python kill other reptiles, the snakes will also eat otters, squirrels, endangered woodstorks and sparrows.

While there are thousands of alligators in the Everglades, Joe Wasilewski, a wildlife biologist and crocodile tracker, said its unknown how many pythons there are.

"We need to set traps and do a proper survey," of the snakes, he said. At least 150 have been captured in the last two years.

The problem arises when people buy pets they are not prepared to care for.

"People will buy these tiny little snakes and if you do everything right, they're six-feet tall in one year. They lose their appeal, or the owner becomes afraid of it. There's no zoo or attraction that will take it," so they release the snakes into the Everglades.

A reproducing snake can have as many as 100 hatchlings, which explains why the snake population has soared, Wasilewski said.

The Burmese snake problem is just part of a larger issue of nonnative animal populations in South Florida, he said. So many iguanas have been discarded in the region that they are gobbling tropical flowers and causing problems for botanists, Wasilewski said.

A 10- or 20-foot python is also large enough to pose a risk to an unwary human, especially a small child, he added.

"I don't think this is an imminent threat. This is not a 'Be afraid, be very afraid situation.'"