This is similar the classic Star Trek Episode the Trouble with Tribbles. Tribbles are born pregnant which is quite a time saver.

In 2003, scientists confirmed that the marbled crayfish were indeed making clones of themselves. They sequenced small bits of DNA from the animals, which bore a striking similarity to a group of crayfish species called Procambarus, native to North America and Central America.

For nearly two decades, marbled crayfish have been multiplying like Tribbles on the legendary "Star Trek" episode. "People would start out with a single animal, and a year later they would have a couple hundred," said Dr. Lyko.

The scientists concluded that the new species got its start when two slough crayfish mated. One of them had a mutation in a sex cell — whether it was an egg or sperm, the scientists can't tell.

Normal sex cells contain a single copy of each chromosome. But the mutant crayfish sex cell had two.