Animal sexual behaviour takes many different forms, including within the same species. Common mating or reproductively motivated systems include monogamy, polyandry, polygamy, and promiscuity. Other sexual behaviour may be reproductively motivated (e.g. sex apparently due to duress or coercion and situational sexual behaviour) or non-reproductively motivated (e.g. interspecific sexuality, sexual arousal from objects or places, sex with dead animals, homosexual sexual behaviour, bisexual sexual behaviour).