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| Genus: | Monocystis |
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 (as M. agilis of the reproductive system of earthworms). [1]
Monocystis lives as an intracellular parasite in its young stage, when it lives in the bundle of developing sperm. It becomes extracellular in its mature stage, living in the contents of seminal vesicles of earthworms. Its infection is so widespread that practically all mature earthworms are found parasitized by this parasite. [2]
The mature adult of Monocystis is a feeding stage called a trophozoite. The young trophozoite lives in the sperm morula (group of developing sperm) of the host; it feeds and grows at the expense of the protoplasm of the developing sperm until all the protoplasm is exhausted and it is surrounded by the tails of the dead sperm cells. In this stage, it is sometimes mistaken for a ciliated organism, but the sperm tails soon detach from its body and the trophozoite becomes free. [2] The adult is an elongated, spindle-shaped, flattened, wormlike creature. Its body is covered by a thick, smooth, and permeable pellicle. The cytoplasm is well differentiated into ectoplasm and endoplasm, the latter containing a large vesicular nucleus. Its nutrition is sporozoic. There are no locomotory organs, but it shows wriggling and gliding movements.
Ontogeny is the origination and development of an organism, usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan.
Trematoda is a class of flatworms known as flukes. They are obligate internal parasites with a complex life cycle requiring at least two hosts. The intermediate host, in which asexual reproduction occurs, is usually a snail. The definitive host, where the flukes sexually reproduce, is a vertebrate. Infection by trematodes can cause disease in all five traditional vertebrate classes: mammals, birds, amphibians, reptiles, and fish.
Histeridae is a family of beetles commonly known as clown beetles or hister beetles. This very diverse group of beetles contains 3,900 species found worldwide. They can be easily identified by their shortened elytra that leaves two of the seven tergites exposed, and their geniculate (elbowed) antennae with clubbed ends. These predatory feeders are most active at night and will fake death if they feel threatened. This family of beetles will occupy almost any kind of niche throughout the world. Hister beetles have proved useful during forensic investigations to help in time of death estimation. Also, certain species are used in the control of livestock pests that infest dung and to control houseflies. Because they are predacious and will even eat other hister beetles, they must be isolated when collected.
Ascaridia galli is a parasitic roundworm belonging to the phylum Nematoda. Nematodes of the genus Ascaridia are essentially intestinal parasites of birds. A. galli is the most prevalent and pathogenic species, especially in domestic fowl, Gallus domesticus. It causes ascaridiasis, a disease of poultry due to heavy worm infection, particularly in chickens and turkeys. It inhabits the small intestine, and can be occasionally seen in commercial eggs.
Retortamonas is a genus of flagellated excavates. It is one of only two genera belonging to the family Retortamonadidae along with the genus Chilomastix. The genus parasitizes a large range of hosts including humans. Species within this genus are considered harmless commensals which reside in the intestine of their host. The wide host diversity is a useful factor given that species are distinguished based on their host rather than morphology. This is because all species share similar morphology, which would present challenges when trying to make classifications based on structural anatomy. Although Retortamonas currently includes over 25 known species, it is possible that some defined species are synonymous, given that such overlapping species have been discovered in the past. Further efforts into learning about this genus must be done such as cross-transmission testing as well as biochemical and genetic studies. One of the most well-known species within this genus is Retortamonas intestinalis, a human parasite that lives in the large intestine of humans.
Spermiogenesis is the final stage of spermatogenesis, during which the spermatids develop into mature spermatozoa. At the beginning of the stage, the spermatid is a more or less circular cell containing a nucleus, Golgi apparatus, centriole and mitochondria; by the end of the process, it has radically transformed into an elongated spermatozoon, complete with a head, midpiece, and tail.
The gregarines are a group of Apicomplexan alveolates, classified as the Gregarinasina or Gregarinia. The large parasites inhabit the intestines of many invertebrates. They are not found in any vertebrates. Gregarines are closely related to both Toxoplasma and Plasmodium, which cause toxoplasmosis and malaria, respectively. Both protists use protein complexes similar to those that are formed by the gregarines for gliding motility and for invading target cells. This makes the gregarines excellent models for studying gliding motility, with the goal of developing treatment options for both toxoplasmosis and malaria. Thousands of different species of gregarine are expected to be found in insects, and 99% of these gregarine species still need to be described. Each insect species can be the host of multiple gregarine species. One of the most-studied gregarines is Gregarina garnhami. In general, gregarines are regarded as a very successful group of parasites, as their hosts are distributed over the entire planet.
The brook lamprey is a small European lamprey species that exclusively inhabits freshwater environments. The species is related to, but distinct from, the North American western brook lamprey.
A gapeworm, also known as a red worm and forked worm, is a parasitic nematode worm that infects the tracheas of certain birds. The resulting disease, known as "gape" occurs when the worms clog and obstruct the airway. The worms are also known as "red worms" or "forked worms" due to their red color and the permanent procreative conjunction of males and females. Gapeworms are common in young, domesticated chickens and turkeys.
Conoidasida is a class of parasitic alveolates in the phylum Apicomplexa. The class was defined in 1988 by Levine and contains two subclasses – the coccidia and the gregarines. All members of this class have a complete, hollow, truncated conoid. Gregarines tend to parasitize invertebrates with the mature gamonts being extracellular; the coccidia mostly infect vertebrates and have intracellular gamonts.
Fusconaia escambia, the narrow pigtoe, or is a freshwater bivalve mussel found in Alabama and northwestern Florida. Narrow pigtoe was first discovered in the Escambia river in Alabama and Florida.
Pseudococcus viburni is a close relative of the grape mealybug and a pest of the vineyards around the world.
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, to spawn refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquatic mammals and reptiles, reproduce through the process of spawning.
An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. They occur worldwide where soil, water, and temperature allow.
Lernaeocera branchialis, sometimes called cod worm, is a parasite of marine fish, found mainly in the North Atlantic. It is a marine copepod which starts life as a small pelagic crustacean larva. It is among the largest of copepods, ranging in size from 2 to 3 millimetres when it matures as a copepodid larva to more than 40 mm as a sessile adult.
Nicothoë astaci or the 'lobster louse' is an ectoparasitic copepod that parasitises the gills of the European lobster species Homarus gammarus. The lobster louse was first reported in 1826 by Audoin & Milne-Edwards. N. astaci has been found on lobsters inhabiting locations including Scotland, Lundy Island in the Bristol Channel and as far south as France and Portugal. The louse possesses a narrow suctorial mouthpart to feed on host haemolymph. Internally, In its adult form, Nicothoe is barely mobile and most likely remains in the same position for most of its life. The parasite occurs in groups, particularly near the base of the gills, and study has gone into its effects on the lobsters, which are considerably important, commercially. Not much is known about its life cycle, since there are significant gaps in knowledge of certain stages of its growth.
The Archigregarinorida are an order of parasitic alveolates in the phylum Apicomplexa. Species in this order infect marine invertebrates — usually annelids, ascidians, hemichordates and sipunculids.
The Eugregarinorida are the most large and diverse order of gregarines — parasitic protists belonging to the phylum Apicomplexa. Eugregarines are found in marine, freshwater and terrestrial habitats. These species possess large trophozoites that are significantly different in morphology and behavior from the sporozoites. This taxon contains most of the known gregarine species.
The annelids, also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecologies – some in marine environments as distinct as tidal zones and hydrothermal vents, others in fresh water, and yet others in moist terrestrial environments.
Chilomastix is a genus of pyriform excavates within the family Retortamonadidae All species within this genus are flagellated, structured with three flagella pointing anteriorly and a fourth contained within the feeding groove. Chilomastix also lacks Golgi apparatus and mitochondria but does possess a single nucleus. The genus parasitizes a wide range of vertebrate hosts, but is known to be typically non-pathogenic, and is therefore classified as harmless. The life cycle of Chilomastix lacks an intermediate host or vector. Chilomastix has a resistant cyst stage responsible for transmission and a trophozoite stage, which is recognized as the feeding stage. Chilomastix mesnili is one of the more studied species in this genus due to the fact it is a human parasite. Therefore, much of the information on this genus is based on what is known about this one species.