- Dactyl
- Dactylus
- denticle
- Denticulate
- Dextral
- Dextrogyrous
- Diametral spicule
- diaphragm
- dichotomous
- diel vertical migration
- Dikinetid
- dimorph
- Diploblastic
- Direct development
- Disc
- disjunct
- dispersal
- distal
- Distal end-piece
- distribution
- diurnal
- diurnal vertical migration
- diverge
- dorsal
- dorsal brim
- Dorsal brush
- dorsal cirrus
- dorsal fin
- Dorsal lip
- dorsal nerve ganglion
- Dorsal ribs
- dorsal seta
- Dorsal side
- Dorsal spine
- dorsal tubercle
- dorsum