Hymenostomes (Order Hymenostomatida) This order marks the starting point for the elaborations found in the remaining ciliates. The feeding apparatus is described in some detail here and the names of structures are applicable later. The first of these structures is the buccal cavity between the cytostome and the buccal overture, which is a line of … Read more
Gymnostomes (Order Gymnostomatida) – Protozoans As the name suggests the mouth is without ciliary organelles. This is a most diverse group of structurally simple ciliates. But diversity has led to considerable changes in classification in recent years. A comparison of current classifications shows that no general agreement has yet been reached. Most species in the … Read more
Ciliates (Class Ciliata) – Protozoans These protozoans have many cilia and nuclei of two sizes. Because the mastigophoran Opalina also has many flagella (or cilia), it is the nuclei that act as the criterion and establish the true ciliates as a distinct group. Other features include a kinety. Holotrichs (Subclass Holotricha) This group is regarded … Read more
Protozoa Subclass Coccidiomo Subclass Coccidiomo This group is distinguished from the previous one by spending the whole of its trophozoite life intracellularly, and by effecting massive reproduction with schizogony. There is only one major order which contains three suborders. These are markedly different from one another. Order Eucoccidia These are parasites of epithelial cells of … Read more
Subclass Gregarinomorpha In this group are placed various parasites with reproductive similarities. The trophozoite is large and feeds in the lumen of the host’s gut or between cells Genetic exchange is achieved by a union of two sporonts (mature trophozoites) prior to gametogenesis. This union and the formation of gametocysts ensures that gametes can find … Read more
Spirotrichs (Subclass Spirotricha) Members of this class are mostly free-living and have a more highly developed AZM than the primitive hymenostomes. The AZM winds clockwise to the cytostome. Many of the more advanced spirotrichs have no somatic cilia but this loss is secondary. There is a wide variety of structure which prevents generalizations on morphology; … Read more
The ciliates (Class Ciliata) These protozoans have many cilia and nuclei of two sizes. Because the mastigophoran Opalina also has many flagella (or cilia), it is the nuclei that act as the criterion and establish the true ciliates as a distinct group. Other features include a kinety system of fibrils and granules for co-ordinating the … Read more
The spore-formers (Class Sporozoa) This class, like many others making up the phylum, is a dumping ground for probably unrelated families and orders. Its characters are based on the fact that all are well-adapted parasites. To this end, reproductive efficiency is exaggerated and structural complexity reduced. The same stages, though not the names, are found … Read more
Class Actinopoda This class contains two orders, Heliozoa and Radiolaria, which are superficially rather similar. Individuals of both orders may have siliceous skeletons arranged as spheres with holes in them. Axopodia, pseudopodia stiffened with axial filaments, project through the holes. Food is caught on the axopodia and is drawn by the movement of the cytoplasm … Read more
Rhizopods (Class Rhizopoda) This class includes the various species of amoebas. Typically amoebas crawl on the surface of the mud, submerged plants, in the spaces between soil particles, or inside animals as parasites. Locomotion is by means of pseudopodia, which may be long and thin but usually unbranched (filopodia), long, thin, and branched, uniting with … Read more