Definition: What is Sporozoa?

Sporozoa is a huge subphylum consist of of countless unicellular, intracellular parasites. Currently, the team is argued to contain end 65,000 species with varying morphological characteristics. Provided that they are strictly parasitic, members of the subphylum space responsible for a range of illness in human beings (e.g. Malaria, Babesiosis, and also Cyclosporiasis, etc).

The bulk of this organisms are likewise characterized through a complex life cycle the not just requires 2 hosts (vertebrate and also invertebrate) but also alternates between sexual and asexual stages. 


* The subphylum Sporozoa is additionally referred to together Apicomplexa in some books.

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* In some books, Sporozoa is ranked together a class rather than a subphylum. 


Some the the most common organisms in this team include:




Coccidia oocysts in a fecal flotation native a cat through Joel Mills / CC BY-SA (

Classification that Sporozoa 

· Kingdom: Protozoa - Single-celled eukaryotes that either exist as parasites or together free-living organisms. Sexual and also asexual reproduction has actually been observed in several of the species.


· Subphylum: Sporozoa - A group that exclusively consists of helminth protozoa. 


Characteristics the Sporozoa 

While part multinucleate develops have been identified during the life cycle of these organisms, lock are normally uninucleate. According to the Levine et al. Classification, every members that this group contain a group of structures collectively known together apical complex that enable them come attach and penetrate organize cells.

As the surname suggests, the great majority the Sporozoa develop sporozoites in ~ a given suggest in their life cycle. This is the motile and also infective type of the organism that causes an illness in the host.

Based on molecule studies, the surface ar proteins (located in the surface coat of the organisms) have been presented to be GPI-anchored. In such parasites as Plasmodium falciparum, this complicated (a biomolecule consisting of carbohydrates, lipids, and also phosphates) is attached come the C-terminus of surface proteins where it acts together a posttranslational change biomolecule that the cabinet surface.

Here, the complex contributes come the pathogenicity the the parasites thereby contributing to the clinical symptom of the an illness caused. 



Unlike the adult/mature develops of part protozoa, sporozoans perform not have actually flagella or cilia provided for locomotion. Because that this reason, they rely on gliding, twisting, and also bending come move.

Whereas gliding allows for energetic zoite displacement, twisting and also bending plot are mainly used for an altering direction during motion. Because that the zoites, gliding simply entails the behind translocation the a junction between the surface ar of the organism and also a substrate along the longitudinal axis of the zoite. 


* While gliding end a surface, these parasites have actually been displayed to leave a trace of circumsporozoite protein. Today, these trails are widely embraced as proof of gliding motility among Sporozoa parasites.


* Gliding the Sporozoans has also been linked with the capping phenomenon where the parasites accumulation on your surface and then release them come the posterior pole.


Gliding also permits the helminth to penetrate host cells in bespeak to maintain an intracellular lifestyle. Because that instance, in order to penetrate red blood cell of the host (an activity that is actin-dependent); the annular junction has been shown to relocate backward over the surface of the parasite (malaria parasite).

Here, the actin-dependent motor reasons the capping of surface molecules thereby bring about the gliding motion that permits the parasite to pass through the surface ar of the organize cell. 


* When it was observed under the microscope, the gliding action can be checked out to show off the development of undulating ridges/waves in the membrane.

Cyclospora oocysts by Sonia Almeria, Hediye N. Cinar and also Jitender P. Dubey / CC through (


Being very an easy organisms, members the the subphylum Sporozoa lack organs required for feeding and digesting food product in their atmosphere (within the cabinet of the host). Because that this reason, they greatly rely on osmosis to absorb nutrients (fluid nutrients). In ~ the host cell, resources of nutrition because that the organism include liquified cytoplasm, dissolved food material, and tissue fluid, etc. 


* For few of the species, feeding has actually been displayed to involve bordering the food (through phagocytic action).

See more: Which Of The Following Cannot Be Preformed While In The Slide Sorter View?


Some the the other features of Sporozoa include:


· While castle are an easy and perform not have numerous of the organelles found in various other eukaryotes, Sporozoa have actually been presented to have micropores

· Schizonts of Plasmodium and also other helminth are capable of phagotrophy (engulf food particles through phagocytic nutrition)

Types of Spores

Sporozoans have additionally been grouped based upon general spore-morphology.

The four groups of Sporozoa based upon general spore morphology include:


· Apicomplexan - type unique oocysts that contain the sporozoites (infective forms of the parasites)

· Microsporan - kind unicellular spores that contain coiled polar tubes

· Haplosporidian - produce unicellular spores lacking polar filaments in ~ the organization of aquatic invertebrates

· Paramyxean - characterized by spore-within-spore arrangements 


As contrasted to a majority of other Protozoa, the facility life cycle that alternates between sexual and asexual step are one of the defining characteristics of Sporozoans. Here, sex-related reproduction produces zygotes that develop to type sporozoites which subsequently reproduce sexually or asexually. 


Sexual and also Asexual Cycles 

For Sporozoans, the sexual process of reproduction involves the formation of the contrary sex gametes that might be structurally similar or different. Because that instance, whereas gametes produced by Coccidiomorpha often tend to be structurally different, those created by Gregarinina are generally similar.

Here, it"s likewise worth noting the for different organisms, various processes are associated in the formation and production the gametes. In Gregarinina, the department of gamont results in the production of gametes. However, in Coccidiomorpha, macrogametes create the growing gamonts (rather than during division) during microgametogenesis. 

The gametes produced by gametocytes then hold together to kind a zygote. When it"s feasible to distinguish the sex gametes through size and shape in some species, this is not feasible in others. To form the zygote, the microgamete penetrates the macrogamete for fertilization.

The zygote created through fertilization of the female gamete goes with sporogony to type sporozoites in ~ the oocysts. This might involve a simple division of the zygote or many divisions depending on the organism. The sporozoites formed throughout this phase room the infective creates that penetrate hold cells and cause disease. 

Within the organize cells, the sporozoites (which are recognized as trophozoites at this stage) can proceed reproducing asexually through a process known together schizogony. This involves division of the nucleus to form a multinuclear schizont that undergoes segment to type individuals well-known as merozoites. Some of these individuals penetrate new cells whereby asexual reproduction proceeds while others develop to type gamonts involved in sexual reproduction. 


* throughout the metagamic period of your life cycle, Sporozoa have the right to also kind spores the are defined by a safety covering. This form of the parasite allows them to make it through unfavorable environmental problems for a long duration of time. 


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Heinz Mehlhorn. (2001). Encyclopedic recommendation of Parasitology: Biology, Structure, Function. 

Levine, Norman D. (2014). Sporozoa. University of veterinary Medicine, university of Illinois, Urbana, Illinois.

M. Prakash. (2008). Molecule Biology of Life. 

Yevgeniy M. Kheysin. (2013). Life Cycles of Coccidia of residential Animals.