prostomium

American  

[proh-stoh-mee-uhm] / proʊˈstoʊ mi əm /

noun

plural

prostomia

1. the unsegmented, preoral portion of the head of certain lower invertebrates.

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prostomium British  

/ prəʊˈstəʊmɪəm /

noun

1. the lobe at the head end of earthworms and other annelids: bears tentacles, palps, etc, or forms part of a sucker or proboscis

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Other Word Forms

• prostomial adjective

Etymology

Origin of prostomium

1865–70; < New Latin < Greek prostómion mouth. See pro- ², stoma, -ium

Example Sentences

The parapodia of Chaetopoda are never coated with dense chitin, and are, therefore, never converted into jaws; the primitive “head-lobe” or prostomium persists, and frequently carries eyes and sensory tentacles.

From Project Gutenberg

Further, in all members of the sub-phylum Chaetopoda the relative position of the prostomium, mouth and peristomium or first ring of the body, retains its primitive character.

From Project Gutenberg

At the same time the prostomium and its appendages cease to be recognizable as distinct elements of the head.

From Project Gutenberg

Pr, The prostomium. m, The mouth.

From Project Gutenberg

The prostomium is essentially a part or outgrowth of the first somite, and cannot be regarded as itself a somite.

From Project Gutenberg