The birth of 18 baby green anacondas to a mother who has spent her entire life in an all-female exhibit has both surprised and taught a new lesson to those working at Boston's New England Aquarium.
Lengthy and expensive DNA testing has confirmed that the babies born in early January were a product of a nonsexual reproduction process known as parthenogenesis, or virgin birth.
Sarah Tempesta is a senior biologist at the New England Aquarium. She says parthenogenesis is more common in the plant and insect worlds, and is extremely rare among vertebrate species.
The New England Aquarium says this is the second confirmed case of parthenogenesis in green anacondas, including three that were born in a zoo in the United Kingdom in 2014.
Only two of the 18 babies born in early January have survived, with one having a cleft lip.
An aquarium worker discovered the newborn snakes in the Amazon exhibit, causing colleagues to dismiss the story as unbelievable until they went in and found 15 stillborn anacondas and three others alive.
One of the surviving babies succumbed to an infection some six weeks later.
Aquarium workers conducted a scheduled physical examination to confirm the gender of snakes in the exhibit.
They also ruled out a delayed embryo implantation because the snakes' 8-year-old mother had been born in the care of a certified reptile organisation and had come to the aquarium at a very young age, with no exposure to adult males.
Aquarium workers believe that the babies are clones of their mother, saying the limited genetic sequencing done shows complete matches on all the sites tested.