''Monocystis (Gr., monos, ''single'' + kystisis, ''bladder'')'' is a genus (the type of the family Monocystidae) of acephaline gregarines (subclass Gregarinasina) not having the protoplasm divided into segments by septa and including internal parasites of

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordat ...

(as ''M. agilis'' of the reproductive system of earthworms).

Habit and habitat

Monocystis lives as an intracellular

parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

in its young stage when it lives in the bundle of developing sperms and becomes extracellular in its mature stage when it lives in the contents of seminal vesicles of earthworms. Its infection is so wide that practically all mature earthworms are found parasitized by this parasite.

Structure

The adult mature of ''Monocystis'' is called

trophozoite A trophozoite (G. ''trope'', nourishment + ''zoon'', animal) is the activated, feeding stage in the life cycle of certain protozoa such as malaria-causing ''Plasmodium falciparum'' and those of the ''Giardia'' group. (The complement of the trophozoi ...

which is a feeding stage. The young trophozoite lives in the sperm

morula A morula (Latin, ''morus'': mulberry) is an early-stage embryo consisting of a solid ball of cells called blastomeres, contained in mammals, and other animals within the zona pellucida shell. The blastomeres are the daughter cells of the zygot ...

(sperm morula is a group of developing sperms) of the host; it feeds and grows at the expense of the protoplasm of the developing sperms until all the protoplasm is exhausted. So, it is now seen to be surrounded by the tails of the dead sperms. In this stage, it is sometimes mistaken to be a ciliated organism. But, soon the sperm tails are detached from its body and the trophozoite becomes free The adult is elongated, spindle shaped, flattened and worm like creature. Body is covered by thick smooth and permeable pellicle. Cytoplasm is well differentiated in to ectoplasm and endoplasm. endoplasm contains a large vesicular nucleus. It nutrition is sporozoic. there are no locomotory organs but it shows wriggling and gliding movements.

References

{{Taxonbar, from=Q18606206 Conoidasida Apicomplexa genera