How to use Protozoa in a sentence
Thus, to begin with, the animal pedigree is divided into two very distinct grades, the Protozoa and the Metazoa.
We have analogies to this in the two nuclei of some of the protozoa, the one being solely for the purpose of propagation, the other being associated with the functional activities of the cell.
Simple protozoa appear in the form of Radiolaria; Lithistid sponges are represented by such forms as Archaeoscyphia, Hexactinellid sponges by Protospongia; Graptolites (Dictyograptus (Dictyonema)) come on in the higher parts of the system.
From the more complex colonial Protozoa the Coelentera are readily separated by their possession of two distinct sets of cells, with diverse functions, arranged in two definite layers, - a condition found in no Protozoan.
The old criterion by which they and other Metazoa were once distinguished from Protozoa, namely, the differentiation of large and small sexual cells from each other and from the remaining cells of the body, has been broken down by the discovery of numerous cases of such differentiation among Protozoa.Advertisement
Nereid worms were abundant and interesting protozoa as well.
They have the same functions as the contractile vacuole of freshwater Protozoa.
Such organisms are therefore termed parasites and medical parasitology is the study of protozoa and helminth infections of man.
Research topics include pathogenesis, virulence factors, immune mechanisms, genetic studies and viruses, prokaryotic organisms, and protozoa.
Protozoa can be found in ponds, pools, or in any place where water is rather stagnant.Advertisement
The plankton is divided into (a) the Zoo-plankton (such as the minute crustacea and the eggs and larva of fishes and many other marine animals); and (b) the Phyto-plankton, that is, the minute algae, diatoms, peridinians, some flagellate protozoa, spores of alga, etc. The investigation of the plankton from a new point of view, begun by Hansen in 1889, was continued by Lohmann at Kiel, by Cleve in Sweden, by Gran and Ostenfeldt in Norway and Denmark, and by Herdman, Allen and others in England.
Many cancer-parasites have been described in cancerous growths, including bacteria, yeasts and protozoa, but the innumerable attempts made to demonstrate the causal infective organism have all completely failed.
Septicaemia, tuberculosis, glanders, fowl-cholera, relapsing fever, and other diseases are now brought definitely within the range of biology, and it is clear that all contagious and infectious diseases are due to the action of bacteria or, in a few cases, to fungi, or to protozoa or other animals.
De Blainville included in his group many unicellular forms such as Noctiluca (see PROTOZOA), sea-anemones, corals, jelly-fish and hydroid polyps, echinoderms, polyzoa and rotifera.
Toxoplasmosis Toxoplasmosis gondii is a protozoa parasite that may causes infection in the brain.Advertisement
The protozoa, transmitted by the bite of tsetse fly, works their way through a victim's bloodstream.
A bite from a tsetse fly is all that's needed to transmit the protozoa, but the parasite's life cycle in a person is very distinct.
When the protozoa begin a path through the blood stream, they infects the lymph systems as well.
The disease is transmittable from mother to child as the protozoa will cross the placenta and infect the fetus.
Modern treatments seek to prevent the spread of the protozoa, terminate the infection in a person and avoid serious side-effects such as blindness.Advertisement
Streptococcal and staphylococcal bacteria are the most common causes of lymphadenitis, although viruses, protozoa, rickettsiae, fungi, and the tuberculosis bacillus can also infect the lymph nodes.
The diagnosis of enterobacterial infections is complicated by the fact that viruses, protozoa, and other types of bacteria can also cause diarrhea.
Milne-Edwards removed the Polyzoa; the group was soon further thinned by the exclusion of the Protozoa on the one hand and the Entozoa on the other; while in 1848 Leuckart and Frey clearly distinguished the Coelenterata from the Echinodermata as a separate sub-kingdom, thus condemning the usage by which the term still continued to be applied to these two groups at least.
These attempts, however, to perpetuate the usage were finally discredited by Huxley's important Lectures on Comparative Anatomy (1864), in which the term was finally abolished, and the "radiate mob" finally distributed among the Echinodermata, Polyzoa, Vermes (Platyhelminthes), Coelenterata and Protozoa.
The chromatin is distributed throughout the cytoplasm in the form of granules which may be regarded as a distributed nucleus corresponding to what Hertwig has designated, in protozoa, chromidia.Advertisement
Animals suffer from the ravages of bot flies (Oestridae) and gad flies (Tabanidae); while the tsetse disease is due to the tsetse fly (Glossina morsitans), carrying the protozoa that cause the disease from one horse to another.
Lime is, in fact, absorbed to an enormous extent by fishes, molluscs, crustacea, calcareous algae and sponges, starfishes, sea-urchins and feather stars, many polyzoa and a multitude of protozoa (mainly the foraminifera).
Grade A Protozoa.
The Rotifera are all aquatic, the majority dwelling in fresh water with Protozoa and Protophyta, as well as Entomostracous Crustacea.
The structural features which the Mollusca do possess in common with other animals belonging to other great phyla of the animal kingdom are those characteristic of the Coelomata, one of the two great grades (the other and lower being that of the Coelentera) into which the higher animals; or Metazoa as distinguished from the Protozoa, are divided.
Unlike the cells of Protozoa, these embryonic cells of the Metazoa do not remain each like its neighbour and capable of independent life, but proceed to arrange themselves into two layers, taking the form of a sac. The cavity of the two-cell-layered sac or diblastula thus formed is the primitive gut or arch-enteron.
Chaetoderma, of which nine species have been described, has similar habits and distribution, but feeds chiefly on Protozoa.
Similarly, while Diatomaceae may be excluded from among Phaeophyceae, though retained among algae, the Cryptomonadaceae and Peridiniaceae, like Euglena and other Chlorophyceae, may be excluded from Thallophyta and ranged among the flagellate Protozoa.
In comparing algae with the great archegoniate series which has doubtless sprung from them, it is natural to inquire to what extent, if any, they present evidence of the existence Peridiniaceae Diatomaceae Cryptomonadaceae - Hydruraceae - EuPHAEOPHYnEAE Protozoa Flagellata protomastigina...
The existence of ciliated micrococci together with the formation of endospores - structures not known in the Cyanophyceae - reminds us of the flagellate Protozoa, e.g.
It may be noted, however, that it is still doubtful whether this organism is to be placed amongst the bacteria or amongst the protozoa.
Linnaeus applied the Latin term Vermes to the modern zoological divisions Mollusca, Coelentera, Protozoa, Tunicata, Echinoderma (qq.v.), as well as to those forms which more modern zoologists have recognized as worms. As a matter of convenience the term Vermes or Vermidea is still employed, for instance in the International Catalogue of Zoological Literature and the Zoological Record, to cover a number of wormlike animals.
It is divided into five major sections covering bacterial pathogens, toxigenic fungi and marine dinoflagellates, protozoa, and viral and virus-like agents.
Toxoplasmosis toxoplasmosis Toxoplasmosis gondii is a protozoa parasite that may causes infection in the brain.
Bacteria (see BACTERIOLOGY) and Cyanophyceae (see ALGAE), which are often grouped together as Schizophyta, are from points of view of both structure and reproduction extremely simple organisms, and stand apart from the remaining groups, which are presumed to have originated directly or indirectly from the Flagellatae, a group of unicellular aquatic organisms combining animal and plant characteristics which may be regarded as the starting-point of unicellular Thallophytes on the one hand and of the Protozoa on the other.
Protozoa' (various groups included).
The geographical distribution is cosmopolitan, as is the case with Protozoa and Protophyta of similar habits.
Haeckel himself, with his pupil MikluchoMaclay, had in the meantime made studies on the growth from the egg of Sponges - studies which resulted in the complete separation of the unicellular or equicellular Protozoa from the Sponges, hitherto confounded with them.
These include Protozoa, three sponges, Vermes, twenty-five Molluscs, numerous Amphipods, fishes of the genera Gobius, Benthophilus and Cobitis, and one mammal (Phoca caspia).
On the ether hand, a survey of the facts of cellular embryology which were accumulated in regard to a variety of classes within a few years of Kovalevsky's work led to a generalization, independently arrived at by Haeckel and Lankester, to the effect that a lower grade of animals may be distinguished, the Protozoa or Plastidozoa, which consist either of single cells or colonies of equiformal cells, and a higher grade, the Metazoa or Enterozoa, in which the egg-cell by " cell division " gives rise to two layers of cells, the endoderm and the ectoderm, surrounding a primitive digestive chamber, the archenteron.