Biology Prefixes and Suffixes: ect- or ecto-

Spitting Cobra
Spitting Cobra - Snakes and other reptiles are ectotherms and must obtain heat from their external environment. Digital Vision/Getty Images

Biology Prefixes and Suffixes: (ecto-)


The prefix (ecto-) comes from the Greek ektos which means outside. (Ecto-) means outer, external, out or outside. Related prefixes include (ex- or exo-).


Ectocytic (ecto-cytic) - outside of a cell.

Ectoderm (ecto-derm) - outer germ layer of a developing embryo that forms skin and nervous tissue.

Ectoenzyme (ecto-enzyme) - an enzyme that is attached to the outer cell membrane and is secreted externally.

Ectohormone (ecto-hormone) - a hormone, such as a pheromone, that is excreted from the body into the external environment.

Ectomere (ecto-mere) - any blastomere (cell resulting from cell division that occurs after fertilization) that forms the embryonic ectoderm.

Ectomorph (ecto-morph) - individual with a tall, lean, thin body type predominated by tissue derived from the ectoderm.

Ectoparasite (ecto-parasite) - a parasite that lives on the outer surface of its host. Examples include fleas, lice and mites.

Ectopia (ecto-pia) - abnormal displacement of an organ or body part outside of it proper location. An example is ectopia cordis, a congenital condition where the heart sits outside of the chest cavity.

Ectopic (ecto-pic) - occurring out of place or in an abnormal position.

Ectophyte (ecto-phyte) - a plant parasite that lives on the outer surface or skin of its host. Ringworm is an example of an ectophyte.

Ectoplasm (ecto-plasm) - the outer area of the cytoplasm in some cells such as protozoans.

Ectosarc (ecto-sarc) - the ectoplasm of a protozoan such as an amoeba.

Ectotherm (ecto-therm) - an organism (like a reptile) that uses external heat to regulate its body temperature.

Ectotrophic (ecto-trophic) - pertaining to organisms that grow and obtain nutrients from the surface of tree roots, such as mycorrhiza fungi.

Ectozoon (ecto-zoon) - an ectoparasite.

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Bailey, Regina. "Biology Prefixes and Suffixes: ect- or ecto-." ThoughtCo, Oct. 27, 2015, Bailey, Regina. (2015, October 27). Biology Prefixes and Suffixes: ect- or ecto-. Retrieved from Bailey, Regina. "Biology Prefixes and Suffixes: ect- or ecto-." ThoughtCo. (accessed January 21, 2018).