ArchaebacteriaChromistaand Archezoa Thomas Cavalier-Smith thought at first, as was almost the consensus at that time, that the difference between eubacteria and archaebacteria was so great particularly considering the genetic distance of ribosomal genes that they needed to be separated into two different kingdoms, hence splitting the empire Bacteria into two kingdoms. He then divided Eubacteria into two subkingdoms:
Protists Protists belong to diverse group of eukaryotic microorganisms. The term protista was first used by Ernst Haeckel in Protists were traditionally subdivided into several groups based on similarities as Chrysophytes, Dinoflagellates, Euglenoids and Slime moulds.
Protists do not have much in common besides a relatively simple organization -- either they are unicellular, or they are multicellular without specialized tissues.
This simple cellular organization distinguishes the protists from other eukaryotes, such as fungi, animals and plants. Protists live in almost any environment that contains liquid water.
Many Protists, such as algae, are photosynthetic and are vital primary producers in ecosystems, particularly in the ocean as part of the plankton. Other Protists, such as the Kinetoplastids and Apicomplexa are responsible for a range of serious human diseases, such as malaria and sleeping sickness.
Comment Chrysophytes The golden algae or chrysophytes are a large group of heterokont algae, found mostly in freshwater. Chromulina Some members are generally amoeboid, with long branching cell extensions, though they pass through flagellate stages as well.
Chrysamoeba and Rhizochrysis are typical of these. Diatoms are a major group of chrysophytes eukaryotic algae and are one of the most common types of phytoplankton. A characteristic feature of diatom cells is that they are encased within a unique cell wall made of silica hydrated silicon dioxide called a frustule.
These frustules show a wide diversity in form, some quite beautiful and ornate, but usually consist of two asymmetrical sides with a split between them, hence the group name. Fossilized remains of diatoms over a billion of years forms Diatomaceous earth.
Diatom Comment Dinoflagellates The dinoflagellates are a large group of flagellate protists. Most are marine plankton, but they are common in fresh water habitats as well. Their populations are distributed depending on temperature, salinity, or depth.
About half of all dinoflagellates are photosynthetic. Most dinoflagellates are unicellular forms with two flagella; one of these extends towards the posterior, called the longitudinal flagellum, while the other forms a lateral circle, called the transverse flagellum.
Red tide is more specifically produced when dinoflagellates are able to reproduce rapidly and copiously on account of the abundant nutrients in the water. Although the resulting red waves are a miraculous sight, they, again, contain toxins that not only affect all marine life in the ocean but the people who consume them as well.
A specific carrier is shellfish.
This can introduce both non-fatal and fatal illness due to the toxins they produce. Botanists subsequently treated the algal division Euglenophyta; thus they were classified as both animals and plants, as they share characteristics with both. The euglenoids are one of the best-known groups of flagellates, commonly found in freshwater especially when it is rich in organic materials.
Euglena viridis Many euglenoids have chloroplasts and produce energy through photosynthesis, but others feed by phagocytosis or strictly by diffusion. Euglenoids are distinguished mainly by the presence of a pellicle, which is composed of proteinaceous strips underneath the cell membrane, supported by dorsal and ventral microtubules.
This varies from rigid to flexible, and gives the cell its shape, often giving it distinctive striations. In many euglenoids the strips can slide past one another, causing an inching motion called metaboly.
Otherwise they move using the flagella. Comment Slime Mould Slime moulds feed on microorganisms in decaying vegetable matter. They can be found in the soil, on lawns, and in the forest commonly on deciduous logs. They are also common on mulch or even in leaf mould which inhabits ditches. These unicellular Amoeba-like are commonly haploid and multiply if they encounter their favorite food, bacteria.
These amoebae can mate if they encounter the correct mating type and form zygotes which then grow into Plasmodia which contain many nuclei without cell membranes between them, which can grow to be meters in size. When the food supply wanes, the Plasmodium will migrate to the surface of its substrate and transform into rigid fruiting bodies.
The fruiting bodies or sporangia are what we commonly see, superficially look like fungi or moulds but they are not related to the true fungi.The 3 domain classification by Carl Woese are Bacteria, Archea and Eucarya (based on ribosomal DNA sequence data) and the five kingdom classification by R.
H. Whittaker are Plantae, Anamalia, Fungi, Protista and Prokaryotes.
R. H. Whittaker enlivened many fields within ecology, systematics and evolution with his insights. on primary production, nutrient cycling patterns and species diversity established new standards for five kingdoms of organisms).
Critical evaluation of Whittaker's contributions is best left to specialists in his various fields of. Dec 19, · In , R.H Whittaker classified living organisms into five kingdoms.
He classified organisms based on various criteria like cell structure, mode of nutrition, lifestyle, etc. There were few organisms which are eukaryotic but . Stylistically, Whittaker departed from the broad review of competing systems that he had used in and presented classification as a choice between two alternatives: Copeland's four-kingdom system and Whittaker's new five-kingdom system.
Both the importance of the choice and the rationale for making it were also new. Jul 06, · Among them, Ernst Haeckel (), Robert Whittaker () and Carl Woese () are few whose contributions are notable. Modern-day of taxonomy has accepted the five kingdom classification which was proposed by R.
H. Whittaker. The basis of his classification is the cell structure, mode, and source of nutrition and the .
Among them, Ernst Haeckel (), Robert Whittaker () and Carl Woese () are few whose contributions are notable. Modern-day of taxonomy have accepted the five kingdom classification which was proposed by R. H. Whittaker. The basis of his classification is the cell structure, mode, and source of nutrition and the structure of the body.