- caeca
- calanoida
- calluses
- Cambrian period
- canine teeth
- caninelike
- cannibalistic
- capacious
- capape
- capsules
- carangid
- carapace
- cardiform teeth
- Caribbean Sea
- carina
- carinate
- cariniform
- carmine
- carnivores
- carnivorous
- carotenoid
- carrion
- cartilage
- cartilaginous
- CAS
- CAS(SU)
- castellate
- catadromous
- caudal
- cellulose
- Cenozoic
- centric
- centromere
- cephalic
- cephalopods
- cephalum
- ceratobranch
- ceratohyal
- chaetognaths
- character
- cheek
- chelate
- chemistry
- chest
- chin
- chironomid
- chitin
- chitons
- cholesterol
- chordata
- chorion
- chromatophore
- chromosome
- cichlid
- ciliata
- circumglobal
- circumpolar
- circumtropical
- cirri
- cirriped
- clade
- cladocerans
- cladogram
- clam
- claspers
- classification
- cleft
- cleithral
- cleptoparasitism
- cliff
- cline
- cloaca
- CLOFNAM
- clupeids
- CM
- CNHM
- coalesced
- coastal
- coelenterates
- coitus
- collar
- colonies
- columnar
- commensalism
- commissure
- common
- competition
- concave
- condyle
- confluent
- conical
- conical teeth
- conspecific
- consumers
- contaminating
- continental
- continental shelf
- Continental slope
- convergence
- convex
- copepod
- copulation
- copulatory organ
- coralligenous
- cordate
- corrugated
- corselet
- cortical
- cosmopolitan
- crab
- crangonidae
- cranium
- crenulate
- crest
- Cretaceous
- crevice
- crown
- cruciform
- crustacea
- ctenoid scale
- cuneiform
- currents
- cusp
- cutaneous
- cutaneous fold
- cycloid scale
- cyprinids