Reproduction allows a species to continue no matter the life span. This happens by the different processes in which an organism duplicates itself. Unlike other organ systems the reproductive systems of higher animals have not really become more complex than that of a less complex organism.
All though the reproductive systems of animals may not get immensely complex, they vary through each phylum. For example, some annelids are hermaphrodites. They reproduce by making sperm and sliding next to each other to fertilize their eggs. This is very different from the reproduction of humans in which a male makes sperm in the testes and ejaculates sperm to the eggs of a female within the ovary.
Some similarities can be noticed between the reproductive processes of a human and an annelid. In fact, all organisms share some similarities reproduction wise. Every organism reproduces asexually or sexually. When an organism reproduces asexually, it does not involve the union of gametes from a male sex cell and a female sex cell. Sexual Reproduction is quite the opposite with the male sex cell ( sperm) and the female sex cell ( ovum) joining together to create a fertilized egg. Either way, sexually or asexually, what is produced grows into a completely new organism. Hermaphroditic animals are both male and female producing both sex cells. Many animals also take care off their young during the growing period of their life.