NOAA's National Ocean Service came out against the reality of mermaids after a documentary-style science fiction program on the Discovery Channel's Animal Planet suggested in May that the body of a mermaid had been found on a beach.

Of course, it wasn't. But the program prompted public inquiries to NOAA, which more commonly deals with questions about weather, water and solar storms.

"No evidence of aquatic humanoids has ever been found," the agency wrote on its "Ocean Facts" page here

Humans have been wondering about mermaids since the Stone Age, as shown in cave paintings of magical female figures made 30,000 years ago, NOAA said.

"But are mermaids real? No evidence of aquatic humanoids has ever been found. Why, then, do they occupy the collective unconscious of nearly all seafaring peoples? That's a question best left to historians, philosophers and anthropologists."

Ben Sherman, a spokesman for the Ocean Service, said the item on mermaids was posted June 27 in response to queries about Discovery's fictional "documentary." There was also interest on a couple of NOAA's Facebook pages, he said in an email to Reuters on Thursday.

"This Ocean Fact received little attention until the Discovery News Channel reposted it with commentary on June 29," Sherman wrote.

The Discovery site - here - suggested NOAA responded because Discovery's documentary-style show, "Mermaids: The Body Found," had painted a convincing picture of the existence of mermaids.

"The show was an 'X-Files' type fanciful mix of state-of-the-art computer generated animation, historical fact, conspiracy theory and real and faked footage sprinkled with enough bits of scientific speculation and real science to make it seem plausible," the Discovery site said.

In fact, NOAA scientists recorded a mysterious sound in the Pacific Ocean in 1997 that they called "The Bloop," and the source of this sound has never been identified. The Discovery program mentioned this finding. Listen to "The Bloop" here

For conspiracy theorists, there is a website called believeinmermaids.com/ that purports to show that it has been "seized" by the Justice Department and Homeland Security Investigations.

"It is a hoax," wrote Ross Feinstein of the U.S. Immigration and Customs Enforcement agency, which oversees the seizure of web sites engaged in criminal activity. Claiming that mermaids exist is not a crime, Feinstein said by telephone.

"This operation is focused on counterfeit goods and piracy, not freedom of speech - including those regarding the existence of mermaids," he wrote. "It is not our agency's position to judge whether or not mermaids exist or don't exist. ... Our agency has no open investigations into any issues regarding mermaids." (Editing by David Lindsey and Vicki Allen)

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