Prostomium (sometimes also called acron) is the first body segment in annelids worms. It is in front of (but does not include) the mouth, being usually a small shelf- or lip-like extension over the dorsal side of the mouth. It sometimes bears antennae and eyes. By feeding, it often functions like a kind of overlip. The shape and composition of prostomium are important for annelid systematics.

The prostomium often also has appendages such as palps and tentacles or cirri. Some polychaetes have a posterior extension with sensory function on it, called caruncle. A ciliated pit or groove at the posterior end of the prostomium is another kind or sensory organ called nuchal organ (or a variety of it, the nuchal epaulette).

ee also



* [ A glossary of invertebrate anatomy]
* [ Polychaete head structures]

External links

* [ The prostomium shapes of various families of polychaetes]

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  • Prostomium —   [zu griechisch stóma »Mund«] das, s/...mi |en, bei Ringelwürmern und Igelwürmern der vorderste, nicht segmentierte Teil des Kopfabschnitts, der vor der Mundöffnung liegt. Der dem Prostomium entsprechende Körperabschnitt bei den Gliederfüßern… …   Universal-Lexikon

  • Prostomium — Pro*sto mi*um, n.; pl. {Prostomia}. [NL., fr. Gr. ? before + ?, ?, mouth.] (Zo[ o]l.) That portion of the head of an annelid situated in front of the mouth. {Pro*sto mi*al}, a. [1913 Webster] …   The Collaborative International Dictionary of English

  • Prostomium — Prostomium, Kopflappen am Vorderende der Annelida (Ringelwürmer) …   Deutsch wörterbuch der biologie

  • prostomium — 1870, Modern Latin, from Gk. prostomion fore mouth, something before the mouth, from pro (see PRO (Cf. pro )) + stoma (see STOMA (Cf. stoma)) …   Etymology dictionary

  • prostomium — [prō stō′mē əm] n. pl. prostomia [prō stō′mēə] [ModL: see PRO 1, STOMA, & IUM] a small, noselike portion of the first body segment in many annelid worms, lying above and overhanging the mouth in earthworms …   English World dictionary

  • Prostomium — Das Prostomium, auch Acron oder Kopflappen genannt, ist die Bezeichnung für die Körperspitze der Ringelwürmer (Annelida); bei Krebstieren und anderen Gliederfüßern ist gleichfalls die Bezeichnung Acron für die Körperspitze gebräuchlich, da man… …   Deutsch Wikipedia

  • prostomium — noun (plural prostomia) Etymology: New Latin, from Greek pro + stoma mouth more at stomach Date: 1870 the portion of the head of an annelid worm (as an earthworm) that is situated in front of the mouth • prostomial adjective …   New Collegiate Dictionary

  • prostomium — n. [Gr. pro, before; stoma, mouth] 1. The anterior preoral unsegmented portion of a segmented animal s body. 2. An acron. 3. (ANNELIDA: Oligochaeta) The anterior protuberance above the mouth in the first segment; a preoral lobe; prostomial adj …   Dictionary of invertebrate zoology

  • prostomium — prostomial, adj. /proh stoh mee euhm/, n., pl. prostomia / mee euh/. the unsegmented, preoral portion of the head of certain lower invertebrates. [1865 70; < NL < Gk prostómion mouth. See PRO 2, STOMA, IUM] * * * …   Universalium

  • prostomium — pro·sto·mi·um …   English syllables

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