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Definition

noun

A large group of protozoans that are characterized by having a special organelle called an apical complex. Most of them are single-celled, parasitic, and spore-forming.

Supplement

This group includes organisms such as coccidian, gregarines, piroplasm, haemogregarines, and malarias. The first apicomplexan protozoon observed was the Eimeria stiedai oocyst in the gall bladder of a rabbit by Anton van Leeuwenhoek in 1674.

Apicomplexans are sometimes taken as synonymous with sporozoans. At other times sporozoans are regarded as only a subset of the apicomplexans.

See also: apical complex, Sprozoan

Related term:

• apicomplexan