Planarians are free living flatworms. Like the other two platyhelminthes, the planarian does not have an endocrine system. They can also reproduce sexually and asexually. However, the asexual planarians are hermaphrodites. The hormonal system of planarians make up for the lack of an endocrine system. The hormonal system regulates steroid hormones used for growth. It is also speculated that the hormonal system can contribute to regeneration.