choana /kōˈə-nə/ noun (pl choˈanae) (zoology)

1. A funnel-shaped aperture
2. (usu in pl) one of the internal nostrils which open into the roof of the mouth in air-breathing vertebrates

choˈanocyte noun (zoology)

A cell in which the flagellum is surrounded by a sheath of protoplasm, found in sponges and stalked protozoa (also collar cell)