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A mystery at the New England Aquarium: How did 2 baby anacondas arrive in an all-female exhibit?

A worker displays one of two baby anacondas recently born by parthenogenesis (no male required) at the New England Aquarium.
A worker displays one of two baby anacondas recently born by parthenogenesis (no male required) at the New England Aquarium.(Nathan Klima for The Boston Globe)

Sometimes babies look like their mother. In this case, the resemblance could be uncanny.

Two baby green anacondas born at the New England Aquarium appear to be exact clones of their mother, Anna — because they were born through a process that doesn’t require fertilization from a male.

The two 2-foot-long baby anacondas, weighing just under a pound, were born through an extremely rare nonsexual process called parthenogenesis, or virgin birth. This is only the second case of it ever recorded in green anacondas. “It’s a little bit of excitement in terms of the birth, but also one of success because the mystery was solved,” aquarium spokesman Tony LaCasse said. He said aquarium officials had been puzzled by the new arrivals in an all-female exhibit. Parthenogenesis is common among plants and insects, the aquarium said, and occurs in the wild.

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The newborn snakes were spotted by aquarium staff in early January in the anacondas’ home in the Amazon exhibit, the aquarium said. Some of Anna’s babies were stillborn, which is common with parthenogenesis, according to the aquarium. Three survived, but one died in a couple of days.

Biologists Sarah Tempesta (left) and Tori Babson held two baby anacondas recently born via a form of asexual reproduction known as parthenogenesis at the New England Aquarium.
Biologists Sarah Tempesta (left) and Tori Babson held two baby anacondas recently born via a form of asexual reproduction known as parthenogenesis at the New England Aquarium. (Nathan Klima for The Boston Globe)

Anacondas do not have difficulty reproducing in aquariums, which is why the aquarium doesn’t keep a male around, LaCasse said.

“When anaconda have young from sexual reproduction, we’re talking about having dozens of young at a time,” LaCasse said. “You can’t place that number of animals in facilities.” During a physical examination, Anna and the two other adult anacondas were evaluated again and confirmed to be female. The staff also looked at possible delayed embryo implantation, but Anna’s history was well-documented. She had come to the aquarium when she was young with no previous exposure to any adult male anacondas, the aquarium said.

That left one final test: looking at their DNA. Tissue samples were sent off for testing. Weeks later, it was confirmed that the babies were created by parthenogenesis, the aquarium said.

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Not all types of parthenogenesis create exact DNA copies with the babies. But the two tiny anacondas appear to be exactly that, LaCasse said.

“This is the product of a very unusual process that we needed to go through testing to confirm what we were suspecting,” LaCasse said.

The babies have not yet been put in the exhibit and are still being taken care of behind the scenes, LaCasse said. They’re being held daily by a biologist to make it easier for them later on in life, especially for medical examinations, he said.

“The more they’re habituated to handling, the better we’re able to handle them, especially when they’re adults,” LaCasse said. “They’re currently very popular with our staff because they’re really taking to being handled.”


Breanne Kovatch can be reached at breanne.kovatch@globe.com.