Giant Louisville Zoo Snake Gives Virgin Birth in First Documented Case in this Species

CONTACT: Kyle Shepherd
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The Louisville Zoo and researchers from the University of Tulsa have discovered that the world’s largest snake is capable of virgin birth also known as parthenogenesis. The Louisville Zoo’s 11 year-old reticulate python affectionately called “Thelma” has given birth to six offspring without the benefit of a male snake.

The 20 foot 200 lb. reticulate python has been housed at the Louisville Zoo for four years without a male.  In the summer of 2012 the snake laid of clutch of 61 eggs. The eggs were covered and brooded by the coiled female for two weeks before being removed by Zoo staff for examination.

“It is not uncommon for a snake to lay infertile eggs, so the staff was surprised when the eggs appeared to be full and healthy instead of shrunken and discolored shells (typical of infertile reptile eggs)” says Bill McMahan, Curator of Ectotherms at the Louisville Zoo.  A decision was made to artificially incubate some of the clutch to ascertain whether the eggs were actually fertile. On September 12, 2012, the first of six healthy reticulate pythons hatched with an average individual weight of 148.3 grams (5.23 ounces).

Shed skins from the mother and all six offspring as well as other biological material were sent to a molecular ecology laboratory in the Department of Biological Sciences at the University of Tulsa, in Oklahoma. Over the next several months, their molecular lab determined through genetic testing and analysis that all six offspring were produced by the mother alone – without sperm from a male snake. This has never been documented before in the world’s largest snake.  In a process known as terminal fusion automixis, cells known as polar bodies behave like sperm and fuse with the egg triggering cell division.

Along with several other authors, McMahan penned a paper accepted for publication in the prestigious Biological Journal of The Linnean Society in late Summer 2014 describing how a 20-foot female reticulate python (Python reticulatus) at the Louisville Zoo produced live offspring without the benefit of a male snake. “It is a very exciting thing to be able to witness something like that first hand,” McMahan adds, “especially something that has never been documented before in this species.”

The reticulate python is the world’s largest snake based on more than a century of documented physical evidence. Some physically assessed specimens have exceeded 25 feet and weighed more than 300 pounds. They reside throughout tropical Southeast Asia: India’s Andaman Islands, the Philippines, Indo-China and through Indonesia’s vast Malay Archipelago.

You can see mom in the HerpAquarium daily where she is on exhibit with another reticulate python.  These six offspring aren’t on exhibit just yet. Due to their size and exhibit space, the Zoo will likely share some of the offspring with other zoos within the Association of Zoos and Aquariums.

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The Louisville Zoo, a non-profit organization and state zoo of Kentucky, is dedicated to bettering the bond between people and our planet by providing excellent care for animals, a great experience for visitors, and leadership in scientific research and conservation education. The Zoo is accredited by the American Alliance of Museums (AAM) and by the Association of Zoos and Aquariums (AZA).

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