- caecotrophy
- caecum
- calluses
- Cambrian period
- canine
- caniniform
- Cap Sainte-Marie
- carina
- carinate
- cariniform
- carnivory
- carpal
- carrion
- cartilage
- castellate
- Categorical data
- caudal
- cellulose
- Cenozoic
- centipedes
- central domain
- Centroid
- centromere
- cephalum
- chameleon
- character
- Character displacement
- chelate
- chemistry
- chiggers
- child killing
- chitin
- choana
- chorion
- chromatophore
- chromosome
- Chronospecies
- cingulid
- cingulum
- circumorbital
- CITES
- cities and islands
- clade
- Cladism
- Cladistic species concept
- Cladistics
- Cladogenesis
- cladogram
- Classification
- clavicle
- cleptoparasitism
- Cline
- clines
- cloaca
- Coadaptation
- coastal
- cochineal
- Coding
- Coefficient of variation
- coelom
- coelomates
- Coevolution
- coitus
- columnar
- commensalism
- Comparative biology
- Comparative method
- competition
- Component analysis
- concave
- condylar process
- condyle
- congeneric
- Congruence
- conical
- coniferous
- Consensus index
- Consensus tree
- Consistency
- Consistency index
- conspecific
- Continental drift
- convergence
- convex
- coprophagy
- copulation
- copulatory organ
- cordate
- coronal suture
- coronoid process
- corpus callosum
- Correlation
- Correlation coefficient
- corrugated
- cortical
- cortisol
- cosmopolitan
- Cosmopolitan species
- Covariance
- Cowper's glands
- cranium
- crenulate
- crepuscular
- Cretaceous
- crista
- cristid
- Critically Endangered
- cruciform
- cuneiform
- currents
- cusp
- cutaneous
- cytogenetics