Scientists were initially baffled as to why so many French oysters aged 12 to 18 months were becoming ruined. As with all pretty young things, the answer lay in their preoccupation with sex:

Young French oysters have fallen prey to a killer virus because they have used up too much energy developing their sex organs, scientists believe.

Ha! Turns out, growing their giant genitals had left the oysters susceptible to a form of herpes:

A warm winter and wet spring left the young oysters especially vulnerable to Oyster Herpesvirus type 1, they say.

The moral of the story? Stick to mussels.

‘Sex link’ to French oyster rout [BBC]