North American dotted wolf spider © James Gerholdt/ Getty
In some fish, frogs and other externally fertilising animals, it’s not unusual for females to be smothered by multiple males jostling for the best position to fertilise her eggs.
And in some internally fertilising species, individuals of either sex may copulate with more than one mate in quick succession.
In only one, though – the North American dotted wolf spider – are females routinely inseminated by two males simultaneously, something made possible by the females having two reproductive openings.
Courting a potentially cannibalistic female is perilous for the males, which is why some suitors adopt the strategy of loitering in the shadows while their rivals take their chances.
Only when the female has been subdued will the observer nip in to join the party.