Prostomium

The prostomium, also called Acron or head cloth, is the name for the body top of the annelid worms ( Annelida ); in crustaceans and other arthropods, the term Acron for the body tip is also common, as it classically summarized both taxa as arthropods and held the prostomium or Acron for homologous. The word derives from the Greek and Latin of stoma, "mouth" and pro, "before".

The prostomium of annelids is usually an unimpressive, rag -like notes before the first segment ( the first 'ring ' ) which can be often obscured the mouth and used in the food intake as a kind of lip. In some types of meeresbewohnenden Vielborstern ( Polychaeta ) it forms together with the following two or three segments, but noticeable, thread-or lobe-shaped attachments, making it with them to form a veritable head region is ( cephalization ). These Vielborstern in the head region also sense organs are concentrated, such as eyes, chemoreceptors, antenna and other tactile organs.