prostomium

anatomy

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Last updated

July 13, 2026

Quick Summary

The prostomium is a distinct anatomical feature found in annelid worms, such as earthworms. It is essentially the anterior-most part of the head, located in front of the mouth. This structure can vary in appearance, from a simple lobe to a more complex projection, and it plays a role in the worm's sensory perception. The term "prostomial" is an adjective used to describe anything related to the prostomium. While the prostomium is a key part of the annelid's external anatomy, it's important to note that this term is specific to annelids and not found in other animal groups like cephalopods.1234

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External features
The first segment, the prostomium, is in front of the mouth and may be a simple lobe or a highly developed projection. The next segment, the peristome, surrounds the mouth and is followed by a series of segments, the total number of which may be limited or unlimited. The…
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The first segment, the prostomium, is in front of the mouth and may be a simple lobe or a highly developed projection. The next segment, the peristome, surrounds the mouth and is followed by a series of segments, the total number of which may be limited or unlimited. The…
Read More