There are some new additions to the wildlife community inside Boston's New England Aquarium: two baby anacondas. The South American snakes are among the biggest in the world.

But the arrival of these little ones took everyone by surprise: They were born in an exhibit that doesn't have any male snakes.

Biologist Tori Babson takes care of all kinds of animals at the New England Aquarium, and says things got especially interesting there late one afternoon in January.

"I was cleaning up my tanks, getting everybody fed for the end of the day," she said. And then she heard something weird.

"One of the event staff walked by the tank and noticed that there were a bunch of little babies in the exhibit."

Babson went to check it out, and sure enough, there they were. Unlike most snake species, anacondas don't lay eggs. They have live births.

"So it looks pretty much like you would imagine,” Babson said. “Tiny baby snake coming out a bigger one."

There were actually 18 babies, each about two feet long, emerging from a 30-pound, 10-foot-long anaconda named Anna.

"We were all quite surprised,” she said. “[We] definitely had no idea that we had a pregnant snake. Equally surprised because there were no males in the exhibit. All four of the adults that are in there are all confirmed females."

The mother anaconda had never encountered a male snake. She did this all on her own. Babson reached into a terrarium and pulled one of the babies out.

"So this this little, almost 5-month-old baby looks almost identical to an adult green anaconda,” she said. “They have black spots all along their dorsal side and their ventral side is more yellow and gray spots with a yellow line going down the middle."

Anacondas at New England Aquarium
Craig LeMoult/WGBH News
Anacondas at New England Aquarium
New England Aquarium Biologist Tori Babson holds a baby anaconda.
Courtesy of New England Aquarium
Anacondas at New England Aquarium
New England Aquarium Biologist Tori Babson holds a baby anaconda.
Courtesy of New England Aquarium
Anacondas at New England Aquarium
Craig LeMoult/WGBH News
Anacondas at New England Aquarium
Courtesy of New England Aquarium
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Reproduction without a male is not unheard of. It’s called parthenogenesis, which translates literally to "virgin birth" from its Greek origin.

"Parthenogenesis is more common in plants and in invertebrates,” said New England Aquarium senior biologist Sarah Tempesta. “So in things like wasps, ants, aphids, you'll see parthenogenesis more frequently than you will in vertebrate species."

But it does sometimes happen in things like lizards and snakes, especially if they're in captivity and kept apart from males. Tempesta said this is the second known case in green anacondas.

"Some species simply clone themselves, so they duplicate their DNA, duplicate their cells, and all their offspring will be completely identical to themselves," she said.

Other times, unfertilized eggs can be fused with other cells from the mother that aren't normally used for reproduction.

"So in that instance of parthenogenesis, her offspring won't be complete clones of herself, because even though it's just her DNA, she's configuring it and rearranging it in a different way," Tempesta explained.

It took several months for the New England Aquarium to get DNA testing back on these snakes. Ultimately, they did confirm, this was parthenogenesis. In fact, these babies do appear to be clones of their mom.

If all that sounds familiar from somewhere, you might remember it was a plot line of the dinosaur movie "Jurassic Park."

“You're implying that a group composed entirely of female animals will breed?" one of the Jurassic Park scientists in the movie incredulously asks Dr. Ian Malcolm, played by Jeff Goldblum.

"No,” Malcolm replies. “I'm simply saying that life, uh, finds a way."

“So this sort of is the same sort of concept,” Tempesta said of that idea in the movie. “Life will find a way, and these females, in the absence of a male, have found another way to create offspring."

Even though it's exceedingly rare, it's not the only time the New England Aquarium has had a case of parthenogenesis.

"We actually have, so recently we confirmed parthenogenesis in epaulette sharks as well," Tempesta said.

They believe it's the only observed case in that species of small sharks. But unfortunately, that offspring didn't survive.

That's one thing about animals that are born this way — they often have deformities or are generally less viable. Of the 18 baby anacondas, 15 were stillborn, and another died within a week. But two survived.

As one of them is held, it wraps around hands, sniffing at wrists the way snakes do, by flicking out its little tongue.

This odd and rare genetic marvel is a bit awe-inspiring. And at this size, it's actually pretty cute.