- Candacia paenelongimana
- Candacia tenuimana
- Candacia varicans
- Candeina nitida
- Cannosphaera antarctica
- Canthocalanus pauper
- Cardiapoda placenta
- Cardiapoda richardi
- Cardisoma guanhumi
- Carinaria challengeri
- Carinaria cithara
- Carinaria cristata
- Carinaria japonica
- Carinaria lamarcki
- Carpilius corallinus
- Carpocanium spp.
- Carposphaera acanthophora
- Carybdea alata
- Castanarium antarcticum
- Castanarium favosum
- Castanarium hookeri
- Castanea amphora
- Castanea globosa
- Castanea henseni
- Castanella borgerti
- Castanella maxima
- Castanella thomsoni
- Castanidium haeckeri
- Castanidium longispinum
- Castanidium moseleyi
- Castanidium spinosum
- Castanidium vanhoeffeni
- Castanidium variabile
- Castanissa nationalis
- Castanissa proteus
- Castanissa schmidti
- Castanissa valdiviae
- Castanopsis fragilis
- Cataleptodius floridanus
- Catostylus tagi
- Cavolinia gibbosa flava
- Cavolinia gibbosa gibbosa
- Cavolinia inflexa imitans
- Cavolinia inflexa inflexa
- Cavolinia inflexa labiata
- Cavolinia tridentata atlantica
- Cavolinia tridentata australis
- Cavolinia uncinata uncinata
- Cenosphaera spp.
- Centraugaptilus cucullatus