The oldest snake in captivity has left experts puzzled by laying eggs without the help of a male.
The 62-year-old ball python produced seven eggs at Saint Louis Zoo in Missouri despite having not been around a mate for at least two decades.
The birth was all the more unusual because the python is not only believed to be the oldest living snake, but also the species typically stops laying eggs long before they reach their sixties.
“She’d definitely be the oldest snake we know of in history” to lay eggs, Mark Wanner, the manager of herpetology at the zoo, said.
It is unusual but not rare, however, for pythons to reproduce asexually, Wanner said, and snakes sometimes store sperm for delayed fertilisation.
The unnamed python laid the eggs on 23 July.
Three of the eggs remain in an incubator and are expected to hatch within a month, two were used for genetic sampling and snakes in the other two did not survive, the St Louis Post-Dispatch reported.
The genetic sampling will show whether the eggs were reproduced sexually or asexually, called facultative parthenogenesis.
The only other ball python at the zoo is a male, aged about 31.
The female was given to the zoo by a private donor in 1961.
She laid a clutch of eggs in 2009 that did not survive, and another in 1990, but those could have been conceived with the male because the snakes had been put in buckets together while keepers cleaned their cages at the time.
Additional reporting by Associated Press