The female duck has a complex body. While males show dominance by forcefully mating with her, she chooses which male will father her ducklings by rejecting and redirecting the seed that doesn't suit her.
Male cuttle fish play the field and often "sneak" into harems posing as females. Once infiltration is complete, the male liberally sows his seed leaving several members of the harem pregnant.
Life and death surround the reproductive activities of salmon. Babies are born into the decay of their dead parents' bodies but manage to avenge their deaths by eating the parasites that attacked them.
Monogamy is the goal of the male garter snake - he's got to be the only one. Once he's mated with his female lover, his hopes are high that no other males come along to 'un-seal' the deal.