Protonephridia

The acanthocephalans lack an excretory system, although some species have been shown to possess flame cells (protonephridia).

These pre- cladistics analyses emphasised as shared features: multiciliated (with multiple cilia per cell), glandular epidermis; rod-shaped secretory bodies or rhabdites; frontal glands or organs; protonephridia ; and acoelomate body organization.