- f-j seta
- faecal pellets
- falcate
- falciger
- Feet
- Fenestrae
- Fibrillar meshwork
- fifth limb
- Filament
- Filiform tentacle
- fin angle
- fin bridge
- Fin lobe
- fin rays
- Fins
- First shell
- fissure
- Fixing apparatus
- Flagellum
- Flank
- flexion
- flexion larva
- flexion stage
- Fold
- Foot
- Footlobe
- Four-edged
- Four-winged
- Fourth shell
- Foveola
- Frames
- Frenulum
- Fringed
- frontal
- frontal lamina
- Frontal margin
- frontal organ
- Frontal plate
- frontal process
- Fundamental spicule
- Funnel
- Funnel cartilage
- Funnel groove
- funnel locking cartilage
- Funnel organ
- Funnel valve
- Funnel-shaped pores
- Furca
- furcate
- furrowed