Concepts of Organization the Leverage of Ciliate Protozoa

Abstract

Biologists have long disputed the question of whether or not one can exploit Protista as technologies to better understand the organization of multicellular organisms. Some have argued that Protozoa must be understood and studied solely in their own terms, not as cells, but as organisms possessing an organization fundamentally different from that of Metazoa. Protozoa represent a world unto themselves having evolved in directions altogether divergent from the typical text-book cell: They are “noncellular” or acellular organisms. Others have argued, to the contrary, that in all its essential details a Protozoon is homologous to a Metazoan cell. Although the term “noncellular” may be used when they were studied entirely on their own, without reference to other forms of life, the term “unicellular” was perfectly applicable to Protozoa when they were compared with multicellular organisms. Still others adopted a middle ground, arguing that though Protozoa show similarities to the basic structure of cells, they have many morphological and physiological characteristics of their own which are not found generally in the cells of Metazoa. In recent years, the question of the uniqueness of Protozoa has arisen anew and moved to the center of controversy in reference to general mechanisms of development and evolution.