A snake at an American zoo has given birth for the second time in two years despite not having had sex.

The yellow-bellied water snake, a resident of Cape Girardeau Conservation Nature Center in Missouri, reproduced on her own in 2014 and again this summer, her keepers say.

The 'virgin birth' - the first known example in this kind of snake - has surprised scientists, who think it is the result of a rare type of asexual reproduction called parthenogenesis.

Another theory, thought unlikely but not impossible, is that the snake simply stored sperm from her time in the wild. But sperm usually dies after a year.

bbabo.Net