Thelma the snake confused then astounded her keepers.
This 6m long (20 ft) python had spent four years alone in Louisville zoo in the US, without ever having met a male of her species. But, somehow, she laid over 61 eggs, producing six healthy babies.
Perhaps she’d managed to secretively mate with a male many years before, and store his sperm all this time?
Genetic tests soon revealed the answer.
Thelma had become the first reticulated python in the world known to have had a real-life virgin birth.
She’d made eggs that contained all the genetic information required to make a daughter; without the need for a father, his sperm or DNA. She’d done it fusing her eggs with a by-product of her dividing cells, called a polar body. This object played the same role as sperm would normally, triggering the egg to develop into an embryo. Each of her offspring contained two copies of half her chromosomes. They were half-clones of Thelma.