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prostomium
[ proh-stoh-mee-uhm ]
noun
- the unsegmented, preoral portion of the head of certain lower invertebrates.
prostomium
/ prəʊˈstəʊmɪəm /
noun
- the lobe at the head end of earthworms and other annelids: bears tentacles, palps, etc, or forms part of a sucker or proboscis
Derived Forms
- proˈstomial, adjective
Other Words From
- pro·stomi·al adjective
Word History and Origins
Origin of prostomium1
Word History and Origins
Origin of prostomium1
Example Sentences
At the same time the prostomium and its appendages cease to be recognizable as distinct elements of the head.
The prostomium is essentially a part or outgrowth of the first somite, and cannot be regarded as itself a somite.
Pr, The prostomium. m, The mouth.
About 1870 the question arose for discussion whether the somites in front of the mouth are to be considered as derived from the prostomium of a Chaetopod-like ancestor.
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.
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