- falcate
- falciger
- fifth limb
- filiform tentacle
- fin angle
- fin bridge
- fin lobe
- fin rays
- fins
- fissure
- flagellum
- foot
- footlobe
- fossa
- foveola
- fringed
- frontal hood
- frontal lamina
- frontal margin
- frontal organ
- frontal plate
- frontal process
- funnel
- funnel groove
- funnel locking cartilage
- funnel organ
- funnel valve
- furcate
- furcilia
- furrowed