Learning Bio-Etymology- Part 6 -PLATYTHELMINTHES
LEARNING BIO- ETYMOLOGY
‘Making Biology students
interested in Etymologies’ !!!
· FUN TO LEARN BIOLOGICAL TERMINOLOGY
· THE LANGUAGE OF BIOLOGIST
· SOWING SEEDS OF SYSTEMATICS / TAXONOMY AT
THE GRASSROOT LEVEL
The 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.
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 wordsforming it and their ‘sense’ is of utmost importance. Accumulation of a treasure of words constitutes what is called ‘Vocabulary’ defined variously as follows:
1. The words of a language.
2. The body of words used in a particular language.
3. All the words that exist in a particular language or subject.
4. A list or collection of the words or phrases of a language, technical field etc.
5. 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 meanings.
PART – 6
PHYLUM : PLATYHELMINTHES
PHYLUM – PLATYHELMINTHES
[Gk. platys = flat + helmins = worms]
The animals commonly known as ‘flatworms’ viz., Planarians, Flukes or Tapeworms etc. are among about 20, 000 living species included under Phylum- Platyhelminthes, more complex than Cnidarians, with a well-defined ‘bilateral symmetry’ and ‘tissue organ grade of body organization’
[Gk. helmins = worms + logos (logy) = study of; discourse of study of; knowledge of] i.e., the branch of Zoology related with the study of Helminths (specially Parasitic worms).
· History related with Helminth worms:
References about Helminth worms and diseases caused by them are found in Bible but Egyptian writings (called Ebers papyrus) refer to intestinal worms, based on the observation of calcified Helminth eggs in mummies, dating about 1200 BC. The Greeks, particularly Hippocrates (460 – 375 BC) also knew about worms from fishes, domesticated animals and humans. The science of Helminthology really became popular in 17th and 18th centuries. The first attempt to classify Parasitic worms was, however, made by Zeder (1800) who recognized 5 different classes of parasitic worms viz., Round worms, Hook worms, Sucking worms, Tapeworms and Bladder worms.
In India, the old timer text, the ‘Atharvaveda’ [around 3,000 BC] mentions about 16 types of ‘Krimees’ (= worms), causing diseases in cattle and man. The great medical treatise of ‘Charaka and Shusruta’ [200 BC – 200 AD] described about 20 different types of worms on the basis of their site of origin / occurrence e.g., Malaja (arising from excreta), Sahara (present in every organism since birth), Kaphaja (arising from Cough) and Raktaja (found in the blood).
· History of Platyhelminthes:
The great Greek Philosopher Aristotle (384 – 322 BC) mentioned about ‘Tapeworms’ but the scientific information about the flatworms was revealed in early 18th Century with the publication of 13th Edition of ‘Systema Naturae’ by Linnaeus (1788) where all ‘flatworms’ were placed under the Order Intestina. Earlier, in 1735 Linnaeus created a Phylum ‘Vermes’ where he included all the Invertebrates, except Insects. Lamarck (1816) attempted to differentiate between flatworms and roundworms. French Naturalist / Zoologist Jean Leopold Nicolas Frederic, Baron Cuvier or Georges Cuvier (1817: 1769 – 1832) included flatworms within Zoophyta or Radiata. German Protestant Theologian Karl August Traugott Vogt or Carl Vogt (1851: 1808 – 1869) included flatworms and Nimertines under ‘Platyelmia’. In 1859 German Anatomist Karl Gegenbaur (1826 – 1903) coined the term ‘Platyhelminthes’ and included 4 Classes viz., Turbellaria, Trematoda, Cestoda and Nimertea but Charles Sedgwick Minot (1852 – 1914) excluded Nemerteans from Platyhelminthes.
· Definition / diagnostics:
Mostly parasitic (some free-living), Triploblastic, Vermiform, Bilaterally symmetrical, Dorso-ventrally flattened, Acoelomate, Monoecious (hermaphroditic) animals with Branched digestive system, Flame cells or protonephridia, simple sense organs, ladder-like nervous system, Mesenchyme (= Mesoderm) filling up the space between various organs and without definite anus, skeletal, respiratory and circulatory systems.
· Triploblastic [Gk. Triploos / triples; Latin triplus = threefold / three + blast (os) = denoting embryonic cell / germ layer of an embryo / germ / sprout + -ic < Latin –icus / Gk. –ikos = the suffix used to form adjectives], i.e., the animal body developing from three primary germ layers viz., Ectoderm, Endoderm and Mesoderm.
· Vermiform [Latin vermis = worm + forma = form] i.e., worm-shaped or worm-like form.
· Bilaterally symmetrical Bilaterally symmetrical [Gk.bi = two + lateros = sides], i.e., body divisible into two identical halves (right and left) only in one plane passing through the median longitudinal axis.
· Dorso-ventrally flattened = body flat in dorso-ventral plane.
· Acoelomate [Gk. a = no, without + koiloma / koilia = hollow, cavity + ata = a group or a group of organisms characterized by a structure]:
There is no coelom, as embryonic mesoderm remains as a solid mass (layer) and the space between the endoderm (gut wall) and the ectoderm (body wall) remains filled with mesodermal tissue called mesenchyme [Gk. mesos = middle + enkhyma = infusion] i.e., a layer infused in the middle; often called ‘packing tissue’ or parenchyma [Gk. para = beside + enkhyma = infusion] i.e., something poured in beside].
· Monoecious (hermaphroditic) animals [Gk. mono = alone, single, one + oiki (on) or oikos = house]; the term used to explain ‘one house’ of male and female organs i.e., male and female sex organs present on the same individual (= hermaphrodite) [= Gk. Hermes + Aphrodite = hermaphrodites]; a mythical son of Hermes and Aphrodite who merged their bodies with a naiad and thereafter possessed both male and female qualities. Hermes was a herald and messenger of God; the Aphrodite a goddess of beauty and love, born when Cronus castrated his father Uranus and threw his genitalia into the sea and naiad a female deity associated with water
Classification & Related Terminology
Traditionally, Phylum – Platyhelminthes is divided into four Classes viz., Turbellaria, Monogenea, Trematoda and Cestoda:
1. Class – Turbellaria (*Planarians): [L. turbella = bustle, stir] i.e., the stirring of water by ciliated ventral epidermis, facilitating in movement of the free-living (freshwater / marine / terrestrial); black, brown, grey or brightly-coloured flat worms.
*Planaria [L. planarius/planus/planum = flat, level, even, plain = lying on a plane / ‘on level ground’]
Order – Acoela: [ Gk. a = no / without + koilia = a cavity] i.e.,
lacking a digestive tract; a pharynx leading to a shapeless mass of digestive cells, where individual cells take up food particles and digest them through phagocytosis.
· Convoluta [L. convolutus = coiled, interwoven, interlaced].
Most likely, this marine animal is so named on account of ‘interwoven’ or ‘interlaced’ circular, longitudinal and longitudinal ‘crossover’ muscle fibres. This so diagnostic that often it is said ‘the remarkable feature of the body wall of many adult acoel flatworms is that longitudinal muscles bend medially and cross each other behind the level of the mouth’.
Order – Rhabdocoela: [Gk. rhabdos = a rod / wand + koilia
= a cavity] i.e., the flatworms (marine, freshwater or terrestrial) with a straight (hollow rod like) gut (intestine).
· Macrostomum [Gk. macros = large + stoma = mouth] i.e., ‘big-mouthed’ free-living marine flatworm, found along the sandy beaches and lagoons.
· Stenostomum [Gk. stenos = narrow + stoma = mouth] i.e., mostly freshwater (some marine also), ‘narrow-mouthed’ flatworms.
Order – Allocoela: [Gk. allos = other, different + koilia = a cavity] i.e., the flatworms having a ‘different’ type of gut cavity i.e., with a bulbous pharynx and straight intestine.
· Prorhynchus: [ Gk. pro = toward the front, forward, front + rhynkhos / rhynchos = a snout, bill or a beak of special type] i.e., the flatworms possessing an armed proboscis-like (projecting snout) structure so resembling the stinging apparatus of Nemertine ‘ribbon worms’ or ‘proboscis worms’(Phylum – Nemertea / Nemertini / Nemertinea / Rhynchocoela).
Further, it is to be noted that the anterior region of these worms is exploratory (sensing like a nose), due to the presence of sensory ciliated pits.
· Plagiostomum: [Gk. plagios = oblique / slanting + stoma = mouth] i.e., flatworms with oblique mouth opening on the antero-ventral side.
Order – Tricladida: [Gk. tri = three, 3 + klados = branch + eidos = form] i.e., any of the Turbellarian flatworms (e.g., a Planarian, like Dugesia) having ‘three-branched’ intestine, one branch being anterior whereas the other two being posterior ones.
· Dugesia: The name of the Genus is named after French Naturalist, Antoine Louis Duges (1797 – 1838); father of an Entomologist Eugenio Duges (1826 – 1895) and Zoologist Alfredo Duges (1826 – 1910). At least 6 taxa are named after Antoine Louis Duges, including Dugesia gonocephala (Duges, 1830).
· Bipallium (Shovel-headed garden worm / Hammer-headed worm / Broad-headed Planarians): [L. bi- = two + pala = shovel / spade] i.e., the head of the worm is shaped like a shovel or pickaxe.
Order – Polycladida: [ Gk. poly / polus = many / numerous + klados = branch + eidos = form] i.e., any of the broad, flattened, brightly coloured Turbellarian flatworms with highly ramified intestine (many primary branches radiating from a central cavity).
· Leptoplana:[Gk. leptos = thin, fine, narrow, slender or ‘stripped’ + L. planus / planum = flat, level, even, plain = lying on a plane / ‘on level ground’] i.e., any of the Polycladids which are quite delicate, thin, stripped, whitish or pale ash coloured marine worms.
· Notoplana: [Gk. noton = back or dorsal + L. planus/planum = flat, level, even, plain = lying on a plane / ‘on level ground’] i.e., the flatworm with a characteristic ‘dorsal’ surface; being keeled (or wedged) and also uniform dark beige-coloured (pale sandy fawn-coloured) mid-dorsally.
· Thysanozoon:[Gk. thysano = fringed or bristled + zoon = animal] i.e., any of the marine flatworms with ‘fringed or bristled’ (= papillated or tuberculated) dorsal surface. The intestine is highly ramified and each branch of the intestine being lodged into these dorsal projections of the body wall.
2. Class – Monogenea: [Gk. monos = single + genea / genos = generation] i.e., any of the parasitic flatworms completing their life cycle only in one host (= only one sexually producing generation). They are strictly host specific, hermaphroditic ectoparasites (attaching to body wall, fins, gills, eyes, oral cavity) of cold-blooded animals (fishes / ambhibia). Some are oviparous, laying eggs directly into water; a free-swimming ciliated larva Oncomiracidium (Proto-Indo-European onkos = hook, barb, grapple + Gk. meirakidion = young girl, boy, lad) hatching out and then infecting another host to complete the life cycle whereas some others are viviparous i.e., giving birth to live offsprings (no egg laying). The posterior end of all the larvae has an adhesive organ always with ‘hooks’ (= ‘onkos’)
Order – Monopisthocotylea: [Gk. monos = single + opisthen = behind / posterior + kotule = any of cup-shaped organs in various animals] i.e., any of the parasitic flatworms having single, symmetrical organ of attachment at the posterior end called ‘opisthaptor’ or simply ‘haptor’.
[Gk. haptikos = able to come in contact with or hapto = to touch i.e., a complex organ of attachment with suckers or hooks]
· Gyrodactylus: [Gk. gyrus/gyro/gyros = circle or turn+ dactylos = finger / digit] i.e., meant literally a ‘finger-shaped’ fish parasite; with 2 pairs of anchor hooks.
Expression of the words ‘gyrus’, ‘gyro’ or ‘gyros’
The expression of the words ‘gyrus’, ‘gyro’ or ‘gyros’ has history into an English name of a dish, the ‘doner kebab’, the word ‘doner’ being borrowed from the Turkish ‘doner kebap’. The Turkish word ‘doner’ has its origin in ‘donmek’ (= to turn or to rotate). Therefore, the Turkish name ‘doner kebap’ literally means ‘rotating roast’. In Greek, too, it was originally called ‘doner’ but later came to be known as ‘gyros’, pronounced as ‘YEE-roh’, (= turn or revolution). ‘Doner kebap’ is a type of ‘kebab’ made of meat cooked on a vertical rotisserie (= spit-roasting). Seasoned meat stacked in the shape of an inverted cone is turned slowly on the rotisserie.
The possible explanation for Gyrodactylus / Dactylogyrus, having ‘gyros’ as a prefix or a suffix The parasite, though is ‘finger-shaped’, yet appears as an ‘inverted cone of seasoned meat stack on a rotisserie’ (= ‘gyros’ = ‘doner kebab’ = meat cooked as ‘spit-roasting’), the broader end corresponding to the ‘opisthaptor’ and narrower end to the anterior end bearing a sucker. [pl. refer to https://www.sciencephoto.com/media/887552/view/gyrodactylus-aquatic-parasite-sem.]
The wrinkled ‘tegument’, under high magnification appears as if meat slices are stacked one above the other in a ‘gyro’.
Diplozoon [Gk. diploos / diplous = double + zoon = animal] i.e., a fish parasitic flatworm where the bodies of two hermaphroditic members fused together like a figure of ‘X’.
Polystoma [Gk. poly = many + stoma = mouth] i.e., amphibian, urinary bladder parasite with so called ‘many mouths’ i.e., anterior end with one mouth and a pair of suckers (appearing as if there are more than one mouth).
3. Class – Trematoda (*Flukes): [Gk. tremat- / trema = hole + eidos = form] i.e., any of numerous flatworms called ‘hole/holed forms’ i.e., in addition to mouth (at the centre of anterior sucker) there are two or more other permanent apertures viz., a gonopore, situated midventrally a little in front of ventral sucker (acetabulum); an excretory pore at the posterior end and a temporary opening of Laurer’s Canal (= copulatory canal) appearing only in the breeding season on the dorsal surface, a little anterior to the middle of body.
*Flukes [= part of an anchor of ship or boat that catches the ground (elaborating the shape of animal); = a barb, or barbed head of a harpoon, spear, arrow or the like (describing the leaf-shaped or lanceolate shape of a ‘Trematode’ worm); = so called ‘fluke’ as resembling a miniature flounder (flatfish)]
Subclass – Digenea: [Gk. dis = double + genea / genos = generation] i.e., they involve at least 2 hosts (as against only one host in Monogeneans),to complete their life cycle and also have two distinct generations viz., sexually reproducing adult (in vertebrate host) and asexually multiplying larval forms on intermediate host(s) viz., Miracidia, Sporocysts, Redia, Cercaria and Metacercaria.
Miracidia:[Gk. meirakidion = young girl, boy, lad] i.e., a free-swimming ciliated larval stage of flukes hatching out of eggs and migrating to snail host.
Sporocysts: [Gk. spora = a seed + kystis = bladder] i.e., a sac-like larval stage inside which develop the next larval stage called Redia.
Redia: [Latin Redia = a name of the Genus after Italian Naturalist Francesco Redi] i.e., the larval stage produced within sporocysts; further developing into additional Rediae or Cercariae. [Geuns Redia = a synonym of Plant Genus Cleidion of the Family Euphorbiaceae]
Cercaria: [Gk. kerkos = tail + -aria = feminine of Latin –arius – ary] i.e., a disc-shaped tailed larva, developing directly from a sporocyst or after Redia.
Metacercaria:[Gk. meta = after + cercaria] i.e., the final larval stage developing ‘after’ Cercaria in an encysted juvenile fluke, also called ‘Marita’ [Latin marita = married woman, wife; feminine of maritus = married man, husband].
Order – Diplostomida: [Gk. diploos / diplous = double + stoma = mouth + eidos = form] i.e., the flatworms appearing to have ‘double mouths’, because of two suckers on the ventral side, the first one being around antero-ventral real opening of mouth whereas the second one being only a ventral sucker (acetabulum) without an opening.
· Schistoma or *Bilharzia (**Blood Fluke):[Gk. skhistos = cloven, divided or skhizo = to split, to cleave + soma = body] i.e., a ‘split body’ or a body which is ‘splitted’; referring to the gynecophoric canal on the dorsal surface of adult male, the female being lodges into the same canal.
The orginal name of the Genus *‘Bilharzia’ was after the name of German Pathologist, Theodor Maximilian Bilharz, who discovered the eggs of the parasite during the course of the post mortem of a dead human body.
The common name **‘Blood Fluke’ is on account of their occurrence in the blood vessels of human beings of the tropics (Africa, East Asia and South America).
· Diplostomum (Eye Flukes): [Gk. diploos / diplous = double + stoma = mouth] i.e., perceived as ‘double-mouthed’, owing to the presence of two suckers. Parasites of fishes and fish-eating birds.
Leucochloridium (Green-banded Brood Sac):[Gk. leukos = white + khloros = pale green] i.e., so called ‘Green-banded Brood Sac’ parasite of birds typically exhibits ‘wider green bands, alternating with narrower white bands; and black or brown spotted at the tips’.
It is quite interesting to notice that the worm in its ‘miracidial’ larval stage migrates to the digestive system of the snail (Succinea sp) host to develop into the next stage, the ‘sporocyst’. The latter grows into long tubes to form swollen ‘brood sacs’ filled with hundreds of ‘cercariae’. These brood sacs enter into the snail’s tentacles (mostly the left one), causing a brilliant transformation of the tentacles into swollen, pulsating green yellow or red, colourful display that mimics a caterpillar or grub.
[NOTE: for more information pl. refer to: zslpublications.onlinelibrary.wiley.com › doi › full › jzo]
Order – Plagiorchiida: [Gk. plagios = oblique / slanting + orchis / orchid = testicle / testes + eidos = form] i.e.,the worms characterized by the placement and morphology of the ‘testes’(= ‘orchis’); the latter being slightly lobed, oblique and present in mid-hind end of the body.
· Fasciola (Liver Fluke): [L. fascia = band, a little bandage, swathe] i.e., the flattened leaf-like body harbouring the liver and bile passages of various mammals; lying fastened to the wall like a bandage.
· Opisthorchis: [Gk. opisthen = behind, posterior + orchis = testicle] i.e., any of the flatworms (parasitic on fishes, cats, dogs and various fish-eating mammals including humans) where the ‘testes’ are located in the posterior end of body.
· Paragonimus: [Gk. para = beside, side-by-side + gonimus = gonads] i.e., any of the flatworms (parasitic on various carnivores; some rodents and pigs) where the ‘testes’ and ‘ovaries’ are located side-by-side.
Subclass –Aspidogastrea:[Gk. aspis = shiled + gaster = gut/stomach/belly] i.e., any of the flatworms (parasitic on freshwater and marine mollusks; cartilaginous and bony fishes; and turtles) with unbranched intestine (= gut), ending into a short caecum (= digestive sac) surrounded (shielded) by muscles. More importantly, there is a single ventral sucker (opisthaptor) covering most of the ventral surface.
Multicotyle: [L. multis = much, many + kotule = any of cup-shaped organs in various animals] i.e., flatworms having a large ventral disc (Baer’s disc; after Karl Ernst von Baer, 1827) with many small alveoli (sucker-lets).
Stichocotyle: [Gk. stikhos = line, row + kotule = any of cup-shaped organs in various animals] i.e., flatworms having a single row of well separated suckers.
4. Class – Cestoda (Tapeworms):[Gk. kestos = girdle, belt, tape, ribbon; ‘of Aphrodite’s charmed girdle’ + eidos = form] i.e., any of the flatworms where the body is quite narrow and highly elongated (max. 20.0 m); resembling a ‘tape’ or ‘ribbon’ or ‘belt’ or to ‘Aphrodite’s charmed girdle’ (= embroidered belt) of Greek mythology (= the magical girdle or ‘cestus’ of Aphrodite, woven with irresistible powers of love and desire).
They all exhibit ‘Pseudometamerism’ [pl. refer to PART – 5 of Bio-etymology], the superficial segmentation or repetition of similar, complete, reproductive individuals (functionally independent); the youngest one being added from the front (anterior end). This kind of segmentation is also called ‘strobilation’ [Gk. strobile / strobilus = twisted plug of lint, shaped like a ‘pine cone’] and each segment is named as proglottid [Gk. proglossis / proglossid = point / tip of the tongue; based on glossa / glotta = tongue; pro = before + glossa / glotta = tongue] because of their shape. Thus, there is serial repetition of ‘proglottids’, each containing a complete set of reproductive organs (independent of the others); as exemplified by all ‘Tapeworm’ examples.
Based on the presence or absence of a ‘scolex’ (= so-called head but a specialized holdfast organ with suckers and hooks and no mouth) and a ‘strobila’, Cestodes are traditionally divided into two Subclasses:
Subclass – Cestodaria: [Gk. kestos = girdle, belt, tape, ribbon; ‘of Aphrodite’s charmed girdle’ +
–aria = feminine of Latin –arius – ary] i.e., diminutive of ‘Cestoda’; unusual, obscure group of ribbon-shaped monoecious tapeworms (more or less fluke-like) without strobila (= monozoic: mono = one + zoon = animal i.e., no serial repetition of complete individuals i.e., proglottids) and a scolex. Primarily parasites of cartilaginous and primitive bony fishes.
Only the 10-hooked ‘decacanth’ larva [Gk. deka = ten, 10 + akantha = thorn, spine] or ‘lycophore’ [Gk. lykos = hook + pherein = to bear or to carry] has some resemblance to the ‘Hexacanth’ larva [Gk. hexa = six, 6 + akantha = thorn, spine] of other Cestodes.
Order – Amphilinidea: [Gk. amphi = on both sides + linen = thread + eidos = form] i.e., any of the tapeworms of sturgeons, other fish or freshwater turtles; with pointed anterior end having invaginated tegument to form teeth and posterior end with a rosette of 10 hooks (carried from the larva).
· Amphilina:[Gk. amphi = on both sides, both kinds, double + L. linum = thread or cloth made from flax fibre] i.e., any of the unsegmented (no proglottids), leaf-like parasitic tapeworms of Sturgeons with both the body ends narrow, the anterior one with a muscular proboscis.
Order – Gyrocotylidea: [Gk. gyrus = circle or turn + kotule = any of cup-shaped organs in various animals + eidos = form] i.e., any of the tapeworm parasites with a posterior rosette-shaped adhesive organ (like opistahptor in Gyrodactylys sp.) and exhibiting similarity with a ‘gyros’ [pl. refer to the meaning expressed in the foregoing with reference to Gyrodactylus or Dactylogyrus].
· Gyrocotyl: [Gk. gyrus = circle or turn + kotule = any of cup-shaped organs in various animals] i.e., any of the unsegmented (no proglottids), oblong parasitic tapeworms of marine Ratfish (Holocephali) with a cup-shaped or funnel-shaped proboscis at the anterior end and a sphincter-muscle or rosette-like adhesive organ at the posterior end.
Subclass – Eucestoda: [Gk. eu = true, well, good + kestos = girdle, belt, tape, ribbon; ‘of Aphrodite’s charmed girdle’ + eidos = form] i.e., true ‘Cestodes’ with long ribbon-like body divided into scolex (Gk. skolex/ scoleco-/scolec-/scoleci = grub, worm; an old Genus of worms; the embryo of an entozoic worm), neck and strobila with many proglottids (= polyzoic; Gk. poly = many + zoon = animal i.e., many complete individuals / proglottids).
The Subclass – Eucestoda is divided into a number of Orders, chiefly segregated on the basis of the diversity of quadrangular knob-like holdfast organ the ‘scolex’ (usually less than 1.0 mm), which may have any one of various organs of attachment viz., bothria (Gk. bothrion / bothrios = small pit or trench; longitudinal slits or sucking grooves; generally two in number), sucking discs and chitinous hooks. In some highly developed ‘tapeworms’ the scolex has four hemispherical muscular sucking discs and a proboscis with hooks. Other forms have complex leaf-like, cup-shaped or fimbriated or retractile spiny proboscis.
Only some important Orders are analyzed, ‘Etymologically’, as under:
Order – Tetraphyllidea: [Gk. tetra- / tettares / tessares = four, 4 + phyllon = leaf + eidos = form] i.e., any of the parasitic tapeworms of Elasmobranch fishes, characterized by a scolex with 4 ‘bothria’ (leaf-like muscular structure).
· Phyllobothrium: [Gk. phyllon = leaf + bothrion / bothrios = small pit or trench; longitudinal slits or sucking grooves] i.e., the tapeworms with 4 leaf-like bothria.
· Acanthobothrium: [Gk. akanthos = spiny + bothrion / bothrios = small pit or trench; longitudinal slits or sucking grooves] i.e., the tapeworm with spiny bothria.
Order – Proteocephalidea: [Gk. protos > proteus = primordial, first born; a sea God who could change shape at will + kephale = head+ eidos = form] i.e., any of the Cestodes of Catfishes, Amphibia or Reptilia with a 4-suckered scolex and also a 5th sucker called ‘an apical sucker’ or ‘apical organ’ (may be earning the name ‘Proteo + kephale’)
· Proeocephalus: [derivation of meaning as of the Order].
· Ophiotaenia: [Gk. ophio / ophis = serpent, snake + taenia = ribbon, tape] i.e., any of the parasitic tapeworms of ‘snakes’.
Order – Diphyllidea: [Gk. di = two, 2 + phyllon = leaf + eidos = form] i.e., intestinal parasites of Elasmobranch fishes with a scolex having ‘two bothria’ and a spiny head stalk.
· Echinobothrium: [Gk. ekhinos = prickly, spiny + bothrion / bothrios = small pit or trench; longitudinal slits or sucking grooves].
Order – Trypamorphyrhyncha (= Tetrarhynchoidea, Trypanorhyncha): [Gk. trypanon = auger, borer, trepan + rhynchos = snout, bill, beak + eidos = form] i.e., the tapeworms of Elasmobranch fishes having scolex with 2 or 4 sessile bothria, armed with 4 retractile spiny tentacles (i.e., a specialized snout region to bore into the host’s gut).
NOTE: Find the same prefix ‘typanon’ is the name of a Protozoan flagellate parasite ‘Typanosoma’.
Order – Pseudophyllidea (= Dibothriocephaloidea): [Gk. pseudes = false + phyllon = leaf + eidos = form] or [Gk. di = two + bothrion / bothrios = small pit or trench; longitudinal slits or sucking grooves + kephale = head + eidos = form] i.e., any of the parasitic tapeworms of freshwater fishes having scolex with ‘false’ bothria; meaning thereby that they are not leaf-like but simply as 2 or 6 groove-like suckers without hooks.
NOTE: Find the same prefix ‘pseudes’ in Protozoan ‘Pseudopodia’ and Nematode’s ‘Pseudocoel’.
· Diphyllobothrium (= Dibothriocephalus): [Gk. di = two, 2 + phyllon = leaf + bothrion / bothrios = small pit or trench; longitudinal slits or sucking grooves] or [Gk. di = two, 2 + bothrion / bothrios = small pit or trench; longitudinal slits or sucking grooves + kephale = head] i.e., the scolex is in the form of two (1 dorsal and 1 ventral) broad bothria (slit-like grooves) without suckers.
This tapeworm is popularly known as ‘broad fish tapeworm’, assumed to be the most common agent of human ‘diphyllobothriasis’; also regarded as the largest tapeworms (up to 9.0 m).
Order – Nippotaenoidea [Japanese: Nippon = native name of Japan + Gk. tainia = ribbon, tape + eidos = form] i.e., the tapeworms from freshwater fishes of Japan; having scolex with single apical sucker.
· Nippotaenia: (meaning same as above).
Order – Caryophyllidea: [Gk. karuophullon / karun = a nut + phyllon = leaf + eidos = form] i.e., the tapeworms from Cypriniform and Siluriform fishes having a simple scolex with shallow grooves or loculi or bothrium-like depressions (= fossate scolex) or without loculi or bothrium-like depressions (= afossate scolex), with shallow suckers or frilled margin; but without hooks.
The scolex, resembling a ‘clove bud’ (Caryophyllus aromatica = Syzygium aromaticum), earned the name for the Order i.e., Caryophyllidea.
Order – Cyclophyllidea (= Taenioidea): [Gk. kuklos = circle + phyllon = leaf + eidos = form] or [Gk. tainia = ribbon, tape + eidos = form] i.e., long, ribbon-shaped tapeworms; the globular scolex having 4 cup-like suckers (= acetabula) and hooks encircling a retractable, cone-like muscular structure, the ‘rostellum’ [L. diminutive of rostrum = small beak or a small process resembling a beak], located at the apex of the scolex.
· Taenia: [Gk. tainia = ribbon, tape] e.g.,
1. Taenia solium (‘armed tapeworm’ or ‘pork tapeworm’): the word ‘solium’, as referred in ‘The Parasites of Man’ by the German medical parasitologist Rudolf Leuckart (1886), appears not to be derived from ‘solus’, but from a Syrian word ‘schuschel’, meaning a ‘chain’ [on account of more than 1,000 proglottids arranged in a chain-like fashion].
‘armed tapeworm’: because of 2 rows of hooks around the rostellum.
‘pork tapeworm’: because of pig being the secondary host.
2. Taenia saginata (‘Disarmed tapeworm’ or ‘Beef Tapeworm’): [Gk. tainia = ribbon, tape + L. saginatus = an animal which is fattened, fatted] i.e., a tapeworm which is ‘fatter’ and ‘heavier’; reaching to enormous sizes (4.0 – 14.0 m; max. 25.0 m).
‘Disarmed tapeworm’: because there are no hooks on the scolex.
‘Beef Tapeworm’: because of cattle and buffaloes being the intermediate host.
· Echinococcus: [Gk. echino = sea urchin, prickle + coccus = a kernel, seed, berry, a spherical microorganism] i.e., a parasite of dog, wolf, fox, cat etc., the larval stage of which forms compound cysts or tumors (= *hydatid cysts) in various organs, appearing like spherical shape of Streptococcus or Staphylococcus bacteria, usually grouped in chains.
*Hydatids [Gk. hudatis / hudatid = water vesicle] occur as fluid-filled sacs containing daughter cysts.
‘Metascolex’ [Gk. meta = after + scolex = worm] In various examples of Tapeworms (like Caryophyllidea, Tetraphyllidea etc.), there are small number of large folds (a sort of collar) just behind the scolex, formed by cuticular and subcuticular layers, have been referred as ‘Metascolex’.
Photograph / Video Gallery of ‘Flatworms’
Fascinating to look at the moving ‘Turbellarians’ / ‘Trematodes’ in their favourite habitats
Watch the following videos
The process of cephalization led to the development of a well-defined head region, bearing light sensitive organs (Ocelli). The following videos will establish the fact that the directional movement shown by the Turbellarian Worms in well corelated with cephalization. The movements are obviously controlled by longitudinal, circular and oblique muscles. They are responsible for the bending and twisting of body and for crawling, too. Waves of contraction of longitudinal muscles, passing from the anterior to posterior end, alternately along the right and left sides, result in the forward movement in a wavy manner. As far as the circular muscles are concerned, their contraction results in elongation of body.
In Planarians (like Dugesia) there is a ‘gliding’ movement along the slime trails by the beating of epidermal cilia (richly ciliated ventral surface). While gliding, the head is kept somewhat raised.
The locomoting ‘Bipallium’ on vertical boundary wall of house.
[Video Photograph by SKG: using SONY Cyber Shot: DSC – H 10]
Watch the ‘gliding’ (aided by ventral ciliated epithelium) and muscular movements of the common ‘brownish’ Planarian (Dugesia) in an enamel tray within the boundaries of a small amount of water, after being procured from the debris washed-out from the roots of the weeds growing in marshy, marginal streams.
[Video Photograph by SKG: using SONY Cyber Shot: DSC – H 10]
Watch the movements, dominated by the involvement of muscles, of a common ‘brownish’ Planarian (Dugesia) in a petri dish, after being procured from the debris washed-out from the roots of the weeds growing in marshy, marginal streams. A pair of dark spots – ‘eyes’ – becomes visible, while the head is being moved / curled / twisted.
[Video Photograph by SKG: using SONY Cyber Shot: DSC – H 10]
Fascinating to watch the live specimens (as numbered 1, 2 & 3 in the still photographs above) of a Digenean Trematode (possibly, Opisthorchis sp.) recovered from the body cavity and adhered to the gut of a freshwater fish (Barilius vagra) from streams of Doon Valley (Uttarakhand). See how impatient is the specimen No. 2 to get into the host’s favourite feeding site.
[Video Photograph by SKG: using SONY Cyber Shot: DSC – H 10]