Double trouble: Report out on two-headed shark found in Keys

04/01/2013 11:56 AM

04/01/2013 11:57 AM

The newest celebrity to emerge from the Florida Keys sports the unfortunate conditions of having two heads, and being dead.

A bull shark fetus with two distinct heads, recovered from the Gulf of Mexico by a Florida Keys fisherman in April 2011, made international news last week when a scientific journal published a study confirming it as the first confirmed case of dicephalia (having two heads) in the species.

An Internet search for "two-headed bull shark" Friday generated nearly 2.8 million hits, many featuring a startling image taken by Patrick Rice, dean of marine science and technology at Florida Keys Community College.

Rice is a co-author of the study published in the April edition of the Journal of Fish Biology. Media outlets reporting the two-headed shark include NBC News, Fox News, National Geographic and Time.

"This is certainly one of those interesting and rarely detected phenomena," said the study's lead author Michael Wagner, assistant professor of fisheries and wildlife at Michigan State University.

"It's good that we have this documented as part of the world's natural history," Wagner said, "but we'd certainly have to find many more before we could draw any conclusions about what caused this."

A fisherman who caught an adult bull shark opened it to find the two-headed fetus in its uterus. He turned it over to the FKCC Marine Science Department, where Rice realized its significance.

The dead shark fetus was sent to Michigan State, where experts used magnetic resonance imaging to confirm that it essentially was an animal with a single tail and two heads, rather than conjoined twins (two animals that share a body organ). Dicephalia occurs when an embryo splitting into twins ceases the separation process.

Shark species like blue sharks and tope sharks have been found with two heads, but the Keys specimen is the first-ever bull shark, according to the study.

Even had it been born alive, the bull shark almost certainly would not have survived long, Wagner said. Animals with such deformities have trouble catching food, and are easy prey for other predators.

"You'll see many more cases of two-headed lizards and snakes," Wagner said. "That's because those organisms are often bred in captivity and the breeders are more likely to observe the anomalies."

Although the shark was found in the Gulf of Mexico after the BP Deepwater Horizon oil spill, Wagner cautioned that pollution cannot be confirmed as a cause of the deformity.

"I could see how some people may want to jump to conclusions," he said. "Making that leap is unwarranted. We simply have no evidence to support that cause or any other."

Join the Discussion

Miami Herald is pleased to provide this opportunity to share information, experiences and observations about what's in the news. Some of the comments may be reprinted elsewhere on the site or in the newspaper. We encourage lively, open debate on the issues of the day, and ask that you refrain from profanity, hate speech, personal comments and remarks that are off point. Thank you for taking the time to offer your thoughts.

Terms of Service