[Foraminifera] See Apertural lip.

[Hydromedusae] Lobe-like extension of the manubrium margin surrounding the mouth opening (see mouth).The lips may be of simple or complicated structure, crenulated, folded, short or elongated, pointed or rounded, armed with cnidocysts distributed uniformly or in clusters, or devoid of them. In the Rathkeidae the lips are elongate, simple, or branched and armed with terminal, and usually also lateral, cnidocyst knobs.

[Pteropoda] A folds/Folds around the mouth of the Thecosomata; in Pseudothecosomata these lips form a proboscis structure (Cymbulia in oral view); (b) also used for the ventral and dorsal shell parts at the aperture in Cavoliniidae (Cavolinia in ventral view)