- CALE
- callus
- Cambrium
- cardiform
- Caribbean
- carina
- carinate
- cariniform
- carnivore
- cartilage
- CASE
- caudad
- caudal
- caudal fold
- caudal joint
- caudal septum
- CBOE
- CCHE
- CDAE
- CDSE
- cellulose
- Cenozoic
- central dorsal rib
- cephalum
- ceras
- cerebral
- CGLE
- CHCE
- chitin
- chitinophore
- chromatin
- chromatophores
- chromosome
- ciliar band
- circumpolar
- clade
- cladogram
- clasper
- clinal variation
- closing mechanism
- closing membrane
- CMEE
- CMSE
- coastal
- coll.
- colony
- columella
- commensalism
- competition
- concave
- conical
- conspecific
- constriction
- Continental Shelf
- Continental Slope
- convex
- COPE
- copepod
- cosmopolitan
- CPAE
- CPNE
- CPSE
- cranial
- crest
- Cretaceous
- CRHE
- cruciform
- ctenidium
- CTHE
- currents
- cutaneous
- cuticle
- cutis
- CVAE
- CVAM
- CVDE
- CVPE
- CWNE
- cytology
- cytoplasm