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Related to ctenidium: ctenidia
n. pl. ctenid·ia (-ē-ə) Zoology
A comblike structure, such as the respiratory apparatus of a mollusk or a row of spines in some insects.
ctenidium(pl. ctenidia) one of the comblike gills present in the mantle of many molluscs, particularly Lamellibranchia.
a spine which occurs in rows on the heads of fleas; called also combs; useful for morphological identification.