Ecdysis: the process of casting the skin; moulting.
Echinate: set with prickles.
Ecology: the science of the relation of organisms to each other and to their surroundings: = ethology. {Scanner's comment: Ethology nowadays refers to studies in animal behaviour, not directly to ecology.}
Ectad: extending outwardly from within.
Ectal: belonging or relating to the outer surface.
Ectoblast: the outer wall of a cell; the ectoderm or epiblast.
Ectoderm: the outer layer of skin: the outer layer of the blastoderm, giving rise to the nervous system and to epithelial structures of the body surface.
Ectognathus: see ectotrophous.
Ectoskeletal: referring to the outside or exoskeleton.
Ectotrachea: the outer surface or layer of the trachea.