Some female snakes can store sperm for five years

From New Scientist:

The rattlesnake (Crotalus adamanteus) in question was collected in Florida in 2005 and kept in a private collection for five years, with no contact with other snakes. In late 2010, she unexpectedly gave birth to 19 snakelets. To find out what had happened, Warren Booth of North Carolina State University in Raleigh took samples of DNA from the mother and her young.

Booth studies "virgin birth", in which a female produces young without any contribution from a male. But in this case the snakelets carried genes that their mother didn't, so she must have mated before she was captured and stored the sperm...

Previous studies have hinted that reptiles can store sperm for several years, but this is the first case confirmed by genetics.

It is not known how they do this.