Codon
Sequence of three adjacent nucleotides, in Messenger RNA or in the corresponding DNA, that determines a particular amino acid.

Coelenterata. A phylum of aquatic invertebrates that includes Hydra, jellyfish, sea anemones, and corals. A coelenterate's body is diploblastic, with two cell layers of the body wall separated by mesoglea, and shows radial symmetry.
The body cavity (coelenteron) is sac-shaped radial symmetry. The body cavity (coelenteron) is sac-shaped, with the opening acting as both mouth and free-swimming medusae (e.g. jellyfish) and as sedentary polyps.
The latter may be colonial (e.g. corals) or solitary (e.g. sea anemones and Hydra). In many coelenterates the life cycle alternates between these two forms.

Coelenteron. The single cavity within the body of a coelenterate. It serves as a gut and as a hydrostatic skeleton, and in some groups eggs and sperm are discharged into it. Has a single opening closable by a sphincter.

Coelomoduct. A ciliated duct connecting the coelom with the external environmental. Coelomoducts provides a means of exit for gametes and waste products; in higher animals they are specialized as oviducts, etc.

Coenocyte. A mass of protoplasm containing many nuclei and enclosed by a cell wall. It is found in certain algae and fungi.

Coenospecies. A group of species which may be capable of forming hybrids with each other.

Coenzyme. An organic non-protein molecule that associates with an enzyme molecule in catalysing biochemical reactions. Coenzymes usually participate in the substrate enzyme interaction by donating or accepting certain chemical groups. Many vitamins are precursors of enzymes.