Squidy

A giant squid has three hearts, blue blood (as their blood does not contain haemoglobin- the cell which pigments human blood red) and most interestingly, when giant squids mate, the male pierces the female’s tentacles numerous times with thin rod-like packages of sperm which inject under the surface. The clincher is that only she will decide whether to use this sperm or that of another friendly male squid. 

How she chooses is still unknown.
But it surely can’t be as complex and painstaking as it is with the human species.