• FUN TO LEARN BIOLOGICAL TERMINOLOGY
• THE LANGUAGE OF BIOLOGISTS
• SOWING SEEDS OF SYSTEMATICS / TAXONOMY
AT THE GRASSROOT LEVEL
This Episode:
This episode of ‘Bio-etymology’ is devoted to analyzing the hidden meanings derived from the Names of various Animal Phyla and Classes, along with the terms specifically used to describe their respective diagnostics, important examples (Genus or species) etc.
‘Making Biology students interested in Etymologies’!!!
Recollecting the Introduction of PART – 1:
At any level, may it be animals in general or Man in particular, there is some structured or indicative or behavioural system of communication. It is simply referred to as a kind of ‘Language’. In a broader sense, ‘Language’ is the method of communication that involves the use of various languages (in various countries) spoken by man. Articulation of words in a definite sequence is the basic of formulating a Language and knowledge of words forming it and their ‘sense’ is of utmost importance. Accumulation of a treasure of words constitutes what is called ‘Vocabulary’ defined variously as follows:
- The words of a language.
- The body of words used in a particular language.
- All the words that exist in a particular language or subject.
- A list or collection of the words or phrases of a language, technical field etc.
- A listing either selective or exhaustive, containing the words and phrases of a language, with meaning or translations into another language.
Over a period of time in past centuries, Science is general and Biology in particular has accumulated a vast array of words to communicate fact(s) or phenomena through deriving their meaning.
A Vast Ocean, the Taxonomy:
Taxonomy, being a ‘classical part’ of Biological Sciences has ever been enjoying /exciting for naturalists [as the knowledge of classical music forms the firm basis of any instrumental or vocal classical and light music]. With the changes in time / climate / habitat characteristics and human interferences, the life had / has to undergo changes, as evidenced by the happenings in the Geological past by the appearance(s) & disappearance(s) of various life forms, new forms (with new modifications and new adaptations) replacing the older ones. Thus, the tree of life was / is bound to change in due course of time and new phylogenetic relationships between various ‘taxa’ bound to be revealed. Advances in taxonomical techniques [like molecular biology, biochemistry etc.] have helped unveiling the secrets of evolutionary processes undergoing under ‘nature’. In the light of the on-going changes, well-thought strategies on the part of Taxonomists are called for, to remain vigilant and maintain consistency in the classifications, requiring revisions and amendments.
Cavalier-Smith’s ‘New Higher Classification of Life’ [detailed ahead] has formed basis of currently available ‘Catalogue of Life (CoL)’; most comprehensive and authoritative global index of species; consisting of a single integrated species checklist and taxonomic hierarchy.
Taxonomicon is biodiversity information system, compiling information from a variety of sources. The agency named ‘Systema Naturae 2000’ is another recent compilation, the focused targets being the Index of life, the Tree of life, the Web of life and the Facts of life.
Born 1965, Dr. SJ Brands (Editor), heads the ‘Universal Taxonomic Services’, Zwaag, Netherlands (w.e.f. 1989) and with reference to ‘Systema Naturae 2000’ it is said that:
“….. an up-to-date historical cross-referenced classification of life anywhere, anytime, based on authoritative scientific literature. ….trying to satisfy the need for insight into the relationships between the classifications and enters into a journey of the vast ocean, called Taxonomy”.
Heirarchic System of Classification:
Animals (or Plants) occur in nature as distinct species. The individuals of a species show similar features and are recognizably distinct from other species. The species which share most of the features are placed into large and more inclusive ‘taxa’, called Genera. Similarly, the Genera are included families and so on. This type of arrangement of ‘taxa’ into an ascending series of over-increasing inclusiveness is called ‘Heirarchic System of Classification’.
Heirarchy: It is a systematic framework of any classification of Plants or animals with sequence of classes (= sets) at different levels in which each class except the lowest one, includes one or more subordinate classes (= sets).
Taxa (sing. Taxon): The disjoint classes at each level are called ‘Taxa’ and the ordinal levels are called ‘ranks’. Taxon is, thus, a taxonomic group which is sufficiently distinct to be worthy of being distinguished by name and to be ranked in a definite category, defined as:
‘a group of real organisms recognized as a formal unit at any level of Heirarchic System of Classification’.
The arrangement of taxa into a taxonomic hierarchy not only serves to easily memorize the things but also has a true biological basis, as the different levels in the hierarchy throw light on evolutionary divergences.
Category: Systematic categories have a valuable role to play in Taxonomy. They allow observing resemblance / appearance of order for the bewildering vast array of natural entities composing any Kingdom (like Animal Kingdom).
A taxonomic ‘category’ is a class, the members of which are all taxa assigned to a given ‘rank’. The species, genus, family, order, class etc. are the names of categories. The species and subspecies are lower categories whereas the rest above the species are called higher categories.
Sponge, Jellyfish, Roundworm, Insect, Starfish, Frog, House Sparrow, Pigeons, Crow, Rat, Cat, Dog, Cow, Bat, Lion. Tiger, Man etc. signify ‘taxa’ to be placed in a species category.
Taxa belonging to a category are often described by ‘category name’ e.g., Passser domesticus, Periplanata americana, Rana tigrina, Homo sapiens etc. are ‘taxa’ of ‘species’ ‘rank’ or belonging to species category. In other words, Homo is a Genus, a taxon of Generic ‘rank’ and assigned to the category ‘Genus’. Hominidae [Kingdom – Animalia, Phylum – Chordata, Class- Mammalia, Order- Primata] is a Family, a taxon of Family ‘rank’, assigned to the category ‘Family’.
The main role, thus, of these categories has been to permit groupings of the natural entities (plants or animals) in a way their natural relationships are explained / exhibited in best possible manner.
Furthermore, it should be remembered that the taxonomic categories and ranks are purely arbitrary in nature but the ‘taxa’, as a group of individual living organisms, alone have any true basis.
-
Linnaean Heirarchy:
-
‘KINGDOM’ format of Classification of Living World – from Linnaeus (1735) to Thomas Cavalier-Smith, Michael Ruggiero & others (2015):
-
-
Haeckel’s 3 Kingdom system:
-
Ernst Haeckel, 1866, [German Zoologist and Naturalist, Philosopher, Physician, Professor, Marine Biologist and Artist, 1834 – 1919] proposed 3 Kingdom system viz., Protista (any Eukaryotic organism), Plantae and Animalia.
-
-
Chatton’s 2 Empire System:
-
Edouard Chatton, 1925 [French Biologist, 1883 – 1947] proposed 2 Empire system viz., Prokaryota and Eukaryota.
-
-
Copeland’s 4 Kingdom System:
-
Herbert Copeland, 1938 [American Biologist, 1902 – 1968] proposed 4 Kingdom System viz., Monera (unicellular Prokaryotic organism, like Bacteria), Protista, Plantae and Animalia.
-
-
Whittakar’s 5 – Kingdom System:
-
Robert Harding Whittaker 1969, (American Plant Ecologist, 1920 –1980) proposed the 5 Kingdom system of classification viz., Protista, Monera, Fungi, Plantae and Animalia.
-
-
Woese’s 6 Kingdom System:
-
Carl Richard Woese & others, 1977 [American Microbiologist and Biophysicist, 1928 – 2012] proposed 6 Kingdom System viz., Eubacteria (Prokaryotes, not having defined, membrane –limited nuclei), Archaebacteria (ancient obligate anaerobe Methanogens, with cell membranes composed of lipids), Protista, Plantae, Fungi and Animalia.
Further, Carl Richard Woese & others, 1990 also proposed 3 Domains viz., Bacteria, Archaea (Unicellular organisms, lacking cell nuclei) and Eucarya (Organisms with well-defined nucleus).
-
-
Cavalier-Smith’s 6 and 7 Kingdom System:
-
Thomas (Tom) Cavalier-Smith, 1998, [Professor of Evolutionary Biology, Oxford University, born 1942] proposed 6 Kingdom System viz., Bacteria, Protozoa, Chromista
(Unicellual and multicellular Eukaryotic organisms, sharing similar photosynthetic plastids e.g., Algae, Diatoms, some Protozoans), Plantae, Fungi and Animalia.
Further, more recently Cavalier-Smith along with Michael Ruggirro [A Senior Science Advisor, Smithsonian’s Integrated Taxonomic System, ITIS, US] & others, 2015, finally proposed a widely acclaimed and consensus 7 Kingdom System classification, ‘New Higher Classification of Life’ viz., Bacteria, Archaea, Protozoa, Chromista, Plantae, Fungi and Animalia, as incorporated in widely acclaimed ‘Catalogue of Life (CoL)’.
-
The New Higher Classification of Life:
Woese’s 6 – Kingdom System
With the advances in molecular biology around 1970, significant differences were found among Prokaryotes, particularly in the structure of cell membrane. Based on these developments, Carl Woese (1978, 1990) classified Prokaryota into Eubacteria and Archaeobacteria, emphasizing that the differences between these two were as high as the ones between them and the Eukaryotes. Later on, this resulted in the formulation of a new higher classification of life into 6 Kingdoms under 3 ‘domains’ viz., Archaea, Bacteria and Eukarya:
Domain I: Archaea
1. Kingdom: Archaebacteria (Methanogens, Halophiles, Thermophiles, Psychrophiles):
Single-celled Prokayotes, with unique ribosomal RNA type (16S, 23S and 5S RNA and 50 –70 proteins; highly resistant to adverse living conditions). Cell wall (composed of rigid surface-layer, protein S-layer and lacking peptidoglycans), allowing them to live in quite inhospitable conditions, such as hot springs and hydrothermal vents. Oxygen, hydrogen, carbon dioxide, sulfur, sulfide may be required for metabolism. Nutrition non-photosynthetic photophosphorylation or chemosynthesis. Reproduction by asexual binary fission, budding or fragmentation.
Domain II: Bacteria
2. Kingdom: Eubacteria (Bacteria, Cyanobacteria, Actinobacteria):
Prokaryotic true Bacteria. Cell wall made of peptidoglycans, immediately outside of the plasma membrane . Some causing serious diseases. Oxygen may be toxic, tolerated or required for metabolism. Nutrition by absorption, photosynthesis or chemosynthesis. Reproduction by asexual binary fission.
Domain III: Eukarya
3. Kingdom: Protista (Protozoa, Green algae, Brown algae, Diatoms, Slime molds):
Eukaryotic (true Nucleus having a membranous covering), may have animal-like cell membranes, plant-like cell walls or may be covered by a pellicle. Most are motile and move with the help of flagella, pseudopodia or cilia. Oxygen required for metabolism. Nutrition by absorption, photosynthesis or ingestion. Reproduction asexual but Meiosis in some, also.
4. Kingdom: Fungi (Yeast, Molds, Mushrooms):
Fungi include both unicellular (yeast and molds) and multicellular (mushrooms) organisms. Cell wall made of complex polysaccharides like chitin and glucans. Oxygen is required for metabolism. Decomposers, acquiring nutrients through absorption. Reproduction sexual or asexual through spore formation.
5. Kingdom: Plantae (Mosses, Liverworts, Ferns, Gymnosperms, Angiosperms):
Eukaryotic with cell wall of cellulose. Oxygen required for metabolism. Nutrition autotrophic (Photosynthesis). Reproduction involves alternation of generations between a sexual (gametophyte) and an asexual phase (sporophyte).
6. Kingdom: Animalia (Porifera, Coelenterata, Helminthes, Annelids, Arthropoda, Mollusca, Echinodermata, Hemichordata, Pisces (Fishes), Amphibians, Reptilia, Aves and Mammalia).
Multicellular eukaryotes. Cell membrane of lipid bi-layer with embedded proteins. Oxygen required for metabolism. Nutrition heterotrophic. Reproduction mostly sexual but asexual also in some lower forms.
7 – Kingdom System by Cavalier-Smith
Following the systems of classification introduced by Carl Linnaeus, Ernst Haeckel, Robert Whittaker and Carl Woese; Thomas (Tom) Cavalier-Smith proposed various schemes of ‘Kingdom’ classification from time to time, ranging from 9, 8, 6 or 7- Kingdom classifications. Ultimately, Cavalier-Smith and a team of his collaborators (Ruggiero et al., 2015) presented a consensus classification of life to include more than 1.6 million species, based on more than 3,000 taxonomists’ opinions in an unified and coherent, hierarchically ranked system known as the Catalogue of Life (CoL). They proposed 2-Superkingdoms (Prokaryota and Eukaryota) and 7-Kingdom classification. In all, 14 ranks have been used from Superkingdom to Order viz., Superkingdom, Kingdom, Subkingdom, Infrakingdom, Superphylum, Phylum, Subphylum, Infraphylum, Superclass, Class, Subclass, Infraclass, Superorder and Order. The proposed 7 – Kingdom Model includes the 2 Prokaryotic Kingdoms viz., Archaea (Archaebacteria) and Bacteria (Eubacteria) and 5 Eukaryotic Kingdoms viz., Protozoa, Chromista (all algae whose chloroplasts contain chlorophyll a and c, as well as various colourless forms), Fungi, Plantae and Animalia.-
Frequently used levels of Heirarchical System of Classification:
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primata
Family: Hominidae
Genus: Homo
Species: sapiens
(Man)
NEW CATEGORY ‘PARVKINGDOM’
[Used by T. Cavalier and Smith, 1993 with reference to the
Classification of Kingdom PROTOZOA]
This category signifies a ‘rank’ intermediate between those denoted by Infra- and Super- . Because of a vast diversity of Infrakingdom – Neozoa [15 Neozoan Phyla], a category of 7 ‘Parvkingdoms’ has been used, after following the prefix ‘parv’, like parvclass and parvorder used by Sibley and Ahlquist [1990, Phylogeny and Classification of Birds: a study in molecular Evolution. Yale Univ. Press, New Haven, Conn.]
Ref.: www.ncbi.nlm.nih.gov › pmc › articles › PMC372943
Kingdom Protozoa and its 18 phyla. – NCBI – NIH by T Cavalier-Smith – 1993
• Bio-etymology: from Kingdom Protozoa to Class Mammalia
Coming back to Bio-etymology, here onwards the prime focus will be on analyzing the meanings of various groups from Protozoa to Mammalia, each one followed the History and the diagnostic definition(s). Attempt is also made to also focus on interesting aspects related with any group.
KINGDOM – PROTOZOA
The word Protozoa has 2 Greek units viz., protos = first; zoon = animal i.e., the animals which arose first in the evolutionary history of life (Archaeozoic to Proterozoic Era about 2.5 – 4.0 billion years ago).
History:
The word Protozoa (sing. Protozoan) was coined by a German Palaeontologist, Zoologist and Botanist, George August Goldfuss (1818) as the Greek equivalent of the German Urthiere [ur, proto + thier, animal = ‘primitive or original animals’]. Goldfuss created Protozoa as a Class, involving the simplest animals.
More than 160 years ago Richard Owen (English Biologist, Anatomist and Palaeontologist, 1804 – 1892) raised Protozoa to the rank of Kingdom (1858, 1859), for the first time separating Protists from Animals and plants at the highest classificatory level. 157 years after Owen, as of 2015, Cavalier-Smith has retained Protozoa as a Kingdom.
The drawings above:
The textual matter will be accompanied [as shown above] by related ‘visuals’ or ‘diagrammatic presentations’, drawn as ‘separator sheets’ or ‘diagrams of museum specimens’ for the ‘Practical Records’ prepared at PG level, some 50 years back (by SK Gupta). This is only to emphasize upon the importance of diagrammatic skills and improvisations made to strengthen the learning process.
The improvisations were adopted to build firm standing about the animals to be seen under microscope (permanent slides) or as ‘museum specimens’ for the laboratory class work. The coloured drawings (more to follow in future up loadings) were made out of ‘poster or transparent colours and the water-proof black ink’, to be used a ‘separator sheets’, separating different items of the practical record.
The ‘sample diagram’ of a ciliate Paramecium caudatum, is drawn by using black ink pen.
A must for a student of science (or otherwise):
A teacher and the like always wished / wish his/her students to follow suit. Good, attractive drawings attract anybodies attention and lead to some kind of awards, may be marks, appreciation, encouragement and motivation to carry on and on, in the same manner!!!
The following quotes will be more inspiring / motivational for the students:
“Drawing is a vision on paper”. – Andrew Loomis.
“Drawing makes you see things clearer and clearer and clearer still. The image is passing through you in a physiological way, into your brain, into your memory – where it stays – it is transmitted by your hands”. – Martin Gayford.
“Drawing is not what one sees but what one can make others see”. – Edgar Degas
The inculcation of drawing skills among Biology Students through improvisations (at the school or college level) is directly related with putting the fundamentals of living organisms under study in sequence i.e., in a natural system of arrangement.
As experienced, the improvisations pave way for understanding the subject deeply/fundamentally, since this allows to stick to a particular object for quite some time, rather than running faster (having no time to stand and stare) or skipping this important exercise, as seen today.
‘Venturing into the depth of Taxonomy, Biology becomes an easy proposition’, must be the foremost task for a Teacher / Mentor to groom his/her pupil in the right earnest.
[Read more from ‘The teachings Tips – An engrossing segment’ of this website].
[Click for ‘Instant Identification of Fishes in Field’ and know more about Taxonomy]
-
Definition / diagnostics:
As per Text Books:
Microscopic unicellular (or acellular) eukaryotic free living (aquatic, damp soil or decaying organic matter), parasitic, symbiotic or commensal organisms; with naked or shelled, symmetrical or asymmetrical; variable shape; feeding heterotrophically viz., plant-like (holophytic), animal-like (holozoic), on the expense of the other (saparozoic) or parasitically (endo- or exo-); with or without locomotory organs (flagella, pseudopodia or cilia); carrying-on gaseous exchange and excretion through general body surface and reproducing by Asexual (fission and budding) and Sexual (by gametes or conjugation).
As per Cavalier-Smith:
The simple diagnosis of Kingdom Protozoa is, “Unicellular phagotrophic eukaryotes with mitochondria”.
Further, the most simple, yet Phylogenetic definition given by Cavalier-Smith is:
“Eukaryotes, other than those that primarily lack mitochondria and peroxisomes (oxidative membrane-bound organelles), which share the derived characters that define the four higher Kingdoms viz., Animalia, Fungi, Plantae and Chromista”.
“Predominantly unicellular, plasmodial or colonial phagotrophic eukaryotes, wall less in the trophic state; primarily possessing mitochondria, peroxisomes and Golgi dictyosomes; chloroplasts (when present) contain neither starch nor phycobilisomes but have stacked thylakoids”. The usage of Kingdom Protozoa thus includes all eukaryotes other than the primitively amitochondrial Archezoa and the 4 eukaryotic Kingdoms viz., Animalia, Fungi, Plantae and Chromista, that were independently derived from Protozoa.At Higher Secondary / Graduate class levels, classification of Protozoa, as Phylum, is sufficient enough to build basic understanding about the representatives of the Phylum.
Fossil Protozoa:
While Protozoans evolved early and have survived to the present day as unicellular organisms, they have undoubtedly undergone considerable evolutionary change. That many species became extinct as others appeared, can be deduced from the limited fossil record of Protozoans. Only a small number of Protozoans, the shelled or testate ‘Foraminiferan’ Amoebae [According Phylum system, belonging to Class Rhizopoda, Order Foraminiferida; and according to Kingdom system, belonging to Phylum Reticulosa and Subphylum Foraminifera], have left the fossil remains. The calcareous shells of Foraminiferans [extinct species about 40,000 and living ones about 10,000] had contributed to the Geological Strata in the ‘chalk’ formed during the Cretaceous Period and the well-developed limestones of Palaeozoic Era and Cenozoic Era (65.5 million years ago to the present). This entirely marine group of Protozoans is extremely important as stratigraphic markers in ‘oil explorations’.
Another group, the Radiolarians also contributed to the fossil remains of late Precambrian times [According Phylum system, belonging to Class Actinopodia, Subclass Radiolaria; and according to Kingdom system, belonging to Phylum Radiozoa and Subphylum Radiolaria].
Oceanic ooze and fossil Protozoa:
‘Ooze’ is defined as sediments at the sea bed, containing about 30% skeletal remains of pelagic microorganisms. Protozoan members of Foraminifera, Radiolaria and Heliozoa [According to Phylum system, Class Actinopodea and Subclass Heliozoa; according to Kingdom system, Phylum Heliozoa] contribute considerably to the ‘ooze’ [soft mud or oceanic ooze]. Their tiny skeletons are made of silica or calcium carbonate. Over million years, the settled skeletons got fossilized and converted into stratified rocks found all over the world. They have been put to various commercial uses viz., filtering agents, abrasive chalk and building stones.
The white chalk cliffs of Dover, England and the limestone beds of Paris, Cairo and North America are exclusively composed of the shells of Foraminiferans. Curiously enough, the city of Paris is indebted to these obscure animals as most of the buildings of Paris are made of limestone almost exclusively of the Foraminiferan Genus Miliolina. Similarly, the great pyramids of Egypt were carved out of the lime stone deposits made by the tests (shells) of early Tertian Foraminiferan, Nummulites. Radiolarian fossils are abundant in hard rocks of the nature of flint and chert (types of sedimentary rocks). They also constitute part of Tripoli Stone, used in abrasive powder.
TO BE PROTOZOA-FRIENDLY, ETYMOLOGICALLY!!!
Memorizing some Protozoa related Etymology:
Sarcomastigophora [Gk. sarcode or sarx = fleshy, + mastix = whip, pherein or ferre = to bear]:
Protozoans bearing fleshy Pseudopodia [Gk. pseudo = false or fake; + podium = little foot] or whip-like Flagella [L. flagellum = whip, scourge] or both as locomotory organs.
e.g., Euglena [Gk. eu = true; + glene = eye ball or eye pupil], Amoeba, Actinophrys etc.
Sporozoa [Gk. sporos = spore; + zoon = animal:
Protozoans which are spore like or their life cycle involves sporogony (spore formation) e.g.,
Plasmodium [L. plasma = mould formation + Gk. odium = like i.e., an organism like a stage of slime mould.
Monocystis [Gk. mono = single; + kystis = bladder i.e., body not divided into chambers i.e., ‘one bladder’ or Acephaline form against Cephaline forms etc.
Cnidospora [Gk. knide = nettle, hair; + sporos = spore]:
Protozoans which involve sporogony in their life cycle with characteristic valved spores having ‘polar filaments (= hair)’ e.g, Nosema.
The Genus Nosema is borrowed from ancient Gk. meaning thereby ‘sickness, plague, affliction’. This actually an intracellular Microsporidian parasite of Arthropods (like Honey Bee, Apis), causing dysentery and paralysis.
Ciliophora [L. cilium = eyelash; + pherein or ferre = to bear]:
Protozoans bearing eyelash-like locomotory organs (sing. Cilium; pl. Cilia) e.g.,
Paramecium (Slipper animalcule) etc.
Paramecium owes its origin from Gk. word paramekes = oval or oblong or para = on one side, against or beside + mekos = length; meaning thereby ‘oblong or oval’ organism.
Acellular : L. a(an)= without + old French celle or Latin cella = storeroom or chamber.
Unicellular: L. uni = one + old French celle or Latin cella = storeroom or chamber.
Protozoans are often called as unicellular or acellular. As their one-celled body performs all the biological function (vital activities of life) like multicellular organisms (or in comparison to those where many cells perform these activities), they are also termed as ‘acellular’.
Heterotrophic: Gk. heteros = other, various, different + trophe = nutrition.
Those animals which cannot produce their own food but taking nutrition from other sources, may be animal or plants.
Holophytic: Gk holos = complete, whole + phyton = plant.
Completely plant-like (phosynthetic) [nutrition].
Holozoic: Gk holos = complete, whole + zoikos = of animals.
Completely animal-like [nutrition] (through ingestion and internal processing).
Saparozoic: Gk. saparos = rotten, putrid + zoikos = of animals.
Feeding on dead or decaying animal matter.
Saparophytic: Gk. saparos = rotten, putrid + phyton = plant.
Feeding on dead or decaying plant matter.
Phagotrophic [L. phagus or Gk. phagein or phagos = to eat + Gk. trophos, trophein = to
nourish or one who nourishes]:
Any individual which eats on the solid particles through ingestion i.e., feeding by engulfing, like food vacuole formation.
There is one frequently used term ‘Trophozoite’ among parasitic Protozoa, where ‘trophos’ is used as prefix to ‘zoon(ite)’, meaning thereby that ‘an individual which feeds’; the term being used for ‘an actively feeding stage’ of a parasite (like Plasmodium).
In another term ‘Bacteriophage’ (virus), ‘phagos’ is used as suffix to ‘bacter’, meaning thereby that ‘which feeds on Bacteria’.
Eukaryota [Gk. eu = true, well: karyon = nut, kernel]:
This term defines those cells which contain a well-defined nucleus (enveloped by nuclear membrane); the ‘nucleus’ originating from Latin meaning thereby ‘kernel or core’.
The parallel term ‘Prokaryota’, signifies the cells which have primitively organized ‘nucleus’ (without a definite membrane envelop); Gk. pro = before; karyon = nut, kernel i.e., ‘a stage before well-defined nucleus’.
Mitochondrion [Gk. mitos = thread + khondrion or khondrios = granule, grain or morsel, lump
of salt]:
‘Thread-granules’, describing the appearance of Mitochondria when microscopists first observed them in 19th century.
Chloroplast [Gk. chloros = pale green + plastos = moulded]:
Cellular organelles containing pale green pigment(s) for Photosynthesis.
Lysosome [Gk. lysis = dissolution + soma = body]:
The membrane bound structures inside the cell, actively used for digestion of engulfed (Phagocytosed) food particles.
Endoplasmic reticulum [Gk. endo = inside + plasma = form or body = rete = net]:
A cellular organelle inside, appearing a membrane-bound net-work.
Foraminifera[Latin forminifer = bearing holes; Latin foramen = hole + –fer = bearing or ferre
= to bear]:
Marine Protozoans with uni- or multi-chambered calcareous shell with one or more openings through which pseudopodia (reticulopodia) emerge out e.g., Elphidium.
Radiolaria [Latin radiolus = small sunbeam or radius = ray].
The meaning indicating about their needle-like pseudopods (radiating like rays, hence called axopodia, with a central microtubular axis); body with a central perforated silicious shell e.g., Thalasicola.
Heliozoa [Greek helios, sun + zoon, animal]:
Hence the common name ‘Sun Animalcules. These spherical Protozoans, similar to Radiolarians, possess ‘axopodia’ radiating like sun-rays but different on account of absence of a central capsule. Shell is made of silicious scales or spines.
Noctiluca [L. nocti-, noct – = moon, lantern or nox = night + lucere = to shine]:
This is an interesting marine, planktonic bioluminescent flagellate (Dinoflagellata), often blooming in large numbers due to pollutional eutrophication in sea water. The glow (luminescence) produced by such a large number of individuals make the sea water appearing as if it is under fire at night (fire of the sea or sea ghost) or appearing coloured red during the day, hence synonymous with the outbreak of the so called ‘red tide’.
Entamoeba [Gk. entos= within, internal + amoeba = change or alteration]:
This refers to a vertebrate parasite of digestive tract causing amoebic dysentery specially by the species Entamoeba histolytica [Gk. histos = tissue + lysis = to dissolve].
Trypanosoma [Gk. trupanon or trypanon = borer, auger + soma = body]:
It is a pathogenic haemoflagellate parasite, so named (Trypanosoma) because of its corkscrew-like movement in dense fluid, the blood.
Trypanosoma gambiense is one species, the causative agent of West African Sleeping Sickness or Gambian Trypanosomiasis (species name gambiense after Gambia, a country of West Africa).
Giardia [named after French Biologist, Alfred Mathiew Giard]:
This genus (often well-known for its bilateral symmetry) is a flagellate (with symmetrically placed 4 pairs of flagella and 2 nuclei) parasite of small intestine of man, causing loose bowels (diarrhea).
Leishmania [named after British Pathologist, William B. Leishman]:
This parasitic flagellate lives inside the phagocytic cells of various organs of vertebrates (like macrophages of the liver, spleen and bone marrow) or gut of the insect hosts. Kala-azar or visceral leishmaniasis is a wide spread disease of India, China and Mediterranean countries, caused by Leishmanis donovani, the name of species after the Irish Medical officer, Charles Donovan, when posted at Madras (Chennai).
Learning process is an on-going process:
Venture more into the fantastic world of Etymology and feel Protozoa-friendly!!!