So far no ninja turtles have been spotted emerging from the nuclear fallout left from Japan's Fukushima disaster, but researchers have nonetheless discovered mutants of a different variety: butterflies, according to

And you know what mutant butterflies mean: mutant caterpillars.

In fact, researchers have discovered that the butterflies' mutations are multiplying at an alarming rate through successive generations. If genetic damage done to one generation can reverberate through successive generations, even if following generations were not exposed to radiation, the findings could mean long-reaching consequences for humans exposed to the fallout.

Unfortunately, the mutations inflicted on the butterflies have not been pretty. They typically involve abnormalities like smaller wings and damaged eyes.

Scientists found that these abnormalities were present in about 12 percent of all pale grass blue butterflies collected as larvae during the height of the Fukushima disaster, history's worst nuclear catastrophe since Chernobyl. After a population of specimens were later bred in a lab outside the fallout zone, the number of butterflies inflicted with abnormalities rose to 18 percent. By the third generation, that figure had nearly doubled to 34 percent.

Even more ominous, researchers also collected 240 specimens from the Fukushima fallout zone six months after the disaster and found that 52 percent of those showed abnormalities. Researchers flagged that number as "a dominantly high ratio."

A comparison test was then carried out on unaffected butterflies. After researchers exposed them to low levels of radiation, abnormalities appeared at a similar rate.

"We have reached the firm conclusion that radiation released from the Fukushima Daiichi plant damaged the genes of the butterflies," said Joji Otaki, associate professor at Ryukyu University in Okinawa, Japan.

Of course, if the radiation from Fukushima had this effect on butterflies, it probably had a similar effect on other species too, possibly even humans. Thousands of people were exposed to radiation following the disaster and subsequent cleanup and rescue attempts. Although no deaths or widespread ill-effects have yet been measured among people who were exposed, the findings on butterflies raise fears that there could be long-term effects, and that a pattern may not fully emerge for a few generations.

Otaki's team is already planning follow-up studies on other animals. Until that research is done, it will be impossible to know for sure whether the results seen in the butterfly population can be applied to other species.

Previous studies done on humans have shown there may be a cause for concern, however. For instance, research done in the aftermath of the Chernobyl disaster, and following the dropping of atomic bombs on Hiroshima and Nagasaki in 1945, has shown that radiation exposure is correlated with a localized spike in the ratio of boy-to-girl births. Other animal studies on radiation exposure also display an elevated risk of stillbirth and birth defects.

Related disaster story on MNN: Best places in the U.S. to survive the apocalypse

Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

Mutant butterflies found emerging from Fukushima radiation
Researchers have discovered that the butterflies' mutations are multiplying at an alarming rate through successive generations. If genetic damage done to one ge