What structures does a flatworm expel solid waste?

Flatworms expel solid waste through a structure called the pharynx, which is a muscular tube that can extend out of their bodies. They use this pharynx to ingest food and also to expel undigested material. Additionally, flatworms possess a network of excretory canals that help in the removal of waste products, primarily through specialized cells called flame cells. These adaptations allow them to efficiently manage waste despite their simple body plan.