‘Making Biology students interested in Etymologies’ !!!
- FUN TO LEARN BIOLOGICAL TERMINOLOGY
- THE LANGUAGE OF BIOLOGISTS
- SOWING SEEDS OF SYSTEMATICS / TAXONOMY AT THE GRASS ROOT LEVEL
- The Episode:
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 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:
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 wordsand 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.
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‘BIO-ETYMOLOGY’ PART 1
CLICK HERE TO VIEW ‘BIO-ETYMOLOGY’ PART 2
PART – 3
PHYLUM – PORIFERA
The word Porifera [Latin porus = pore; phoros, pherein or Latin ferre = to bear or to carry] i.e., means the animals provided with numerous minute pores on the body (‘pore bearers’), called Ostia [Latin ostium (sing.) = door, opening] through which a continuous current of outside waters drawn into the body and after circulating through a system of simple to complex canal system comes out through large pores, the Oscula [Latin osculates; past participle of osculari = to kiss; from osculum = a kiss, pretty mouth, sweet mouth; = little mouth; dimunitive of os = mouth]. For their ability to absorb and withhold fluids, these animals have been familiar as ‘sponges’ [Noun = sponge; verb = sponged , sponging i.e., to clean , soak up or drab with sponge].
- History:
Aristotle (384 – 322 BC) mentioned about sponges. Linnaeus (1758), Cuvier (1796) and Lamarck (1801) included sponges, together with Coelenterates, under the group ‘Zoophyta’ [plant-like animals]. Robert Grant (1825) recognized them as to be animals and coined the term Porifera for them.
Schulze (1878), Butschli (1884), Sollas (1884) and Delage (1898) separated sponges from other ‘metazoans’ on the basis of embryological studies and suggested a separate group, ‘Parazoa’ for them.
- Animal Nature of Sponges:
The animal nature of sponges was well established on the basis of the following facts:
1. Absence of cell wall made of cellulose.
2. Feeding on ingressed (through water current) solid food particles i.e., holozoic mode of nutrition.
3. Presence of a free swimming, ciliated larval stages, similar to other marine animals.
- Definition / diagnostics:
Aquatic (freshwater about 2.0%; or marine about 98% from intertidal zone up to 8,500,0 m) sedentary, solitary or colonial; vase-shaped, cylindrical, cushion-shaped or branched; radially symmetrical or asymmetrical; multicellular animals without tissue (only ‘cellular level’ of body organization), cells being loosely arranged into outer Pinacoderm1 (dermal epithelium) and inner Choanoderm2 (gastral epithelium) with a gelatinous non-cellular Mesenchyme3 in between. Loosely arranged cells are kept in place by a well-defined skeletal system made of calcareous or silicious spicules4 or of sulphur containing fibrous protein spongin5. Gross anatomy includes a system of pores and canals (or chambers) for circulation of vital stream of water. Gross anatomy includes a system of pores and canals for maintaining the vitality of these animals through circulation of a current of water through a definite passage. Reproduction by asexual or sexual means.
1. Pinacoderm – Dermal epithelium made of Pinacocytes [Gr.pinkos= plank + kytos = cell] i.e., the cells covering the outer surface as well as inner surfaces of spongocoel or incurrent canals (depending upon the type of canal system).
2. Choanoderm – Gastral epithelium made of Choanocytes [Gr. choane = funnel + kytos = cell] i.e., the collared or funnel-shaped flagellated cells lining the spongocoel or radial canals or flagellated chambers (depending upon the type of canal system).
3. Mesenchyme – A layer between the Pinacoderm and the Coanoderm [Gr. mesos = middle + enchyme = infusion].
4. Spicules – Latin specula, speculum; diminutive of spica = ear of grain or a pointed structure; i.e., the minute, crystalline, calcareous or silicious, pointed, spiny skeletal structures, may be large (–mega) or small (-micro), respectively called as megascleres or microscleres.
5. Spongin – Latin spongia = sponge + Gk. –inor –ine= a suffix to denote ‘present within’.
- Individuality of Sponges:
Whether sponges are individuals or colonies, has been a debated issue and good number of divergent have been expressed but based on morphological and physiological considerations, an Osculum with its associated canal system represents a sponge individual. In other words, a sponge with a single osculum is a solitary individual whereas that with several oscula may represent a colony by vaguely indicated individuals.
- Regeneration in sponges:
The sponges, correlated with their low grade of body organization, exhibit a high degree of regeneration i.e., replacing their injured or lost parts. If an individual is cut or mashed into several pieces and kept in suitable, natural living medium, all will grow into a full-sized sponge, provided that amoebocytes and choanocytes are present in the pieces. Among various types of amoebocytes, the ‘Archaeocytes’ are termed as ‘totipotent’ cells, as they can give rise to any type of cells within the sponge, including the germ cells.
- Fossil Record:
Sponges are represented in fossil records since Precambrian but had undergone repeated rediations in the Palaeozoic and Mesozoic Eras, attaining their greatest diversity in the Cretaceous period. The oldest sponge (Palaeophragmodictya; a Heaxactinellid sponge) in the fossil record, dating to 650 – 543 million years ago (the latest time of Proterozoic), was described in 1996 from Southern Australia.
TO BE PORIFERA-FRIENDLY, ETYMOLOGICALLY!!!
- Memorizing some Porifera related Etymology:
Terms Related with Classification
- Class: Calcarea or Calcispongiae:
[Latin calcarius = of or pertaining to lime or calx, calcis =lime + spongia = a sponge] i.e., the sponges whose skeleton (spicules) is made of about 87.0% calcium carbonate (= Calcareous sponges).
[Greek homos = one and the same; same, equal, like + koilos = hollow] i.e, the sponges with homogenous internal cavity (spongocoel without foldings); choanocytes directly lining the spongocoel [Gk. sponges = sponge + koilos = hollow] and the course of water current is as follows:
Order: Homocoela or Asconosa:
The alternative name ‘Asconosa’ is indicatve of simple ‘Ascon’ type of sponges [Greek askos = wineskin, an animal’s skin sewn up to hold wine] owing to sponges shaped like ‘wineskin’ e.g.,
Leucosolenia[Gk. leucos = white + solen = channel or pipe] [Images]i.e., a colonial sponge with a mass of whitish tubes shaped like a bunch of grapes or bananas.
and
Clathrina [Latin clathri = lattice + Italian, Spanish and Latin -ina = denoting names of animal or plant groups] [Images]i.e., the name of the Genus indicates about the whitish or yellow irregular mass of anastomosing (forming a sort of lattice) tubes, massively encrusting into a globular mass with smooth surface and without stalk.
Order: Heterocoela or Syconosa:
[Gk. heteros = different + koilos = hollow]
Sponges having a cavity (spongocoel) inside, different from ‘homocoela’ i.e., body wall has undergone folding with choanocytes being shifted to the
radial canals, alternating with incurrent canals, receiving water from outside through ostia and connected with radial canals with openings called prosopyles (Gk. pros = near + pyle = gate, opening). Openings of radial canals into spongocoel are called apopyles (Gk. apos = away from + pyle = gate, opening); as exemplified by Scypha (= Sycon)[Images].
The course of water current is as follows:
………. READ MORE for the term Scypha, in PART – 1 of BIO-Etymology.
The alternative name ‘Syconosa’ is derived from Gk. word sykon, meaning thereby ‘a fig’ i.e., the interior of the sponges involved appears like the wall of a ‘fig’.
2.Class: Hexactinellida or Hyalospongiae:
[Gk. hex or hexa = six + actis = ray + eidos = shape or form; Gk. hyalos = glass + sponges = sponge].
The group involving the sponges with six-rayed, triaxon silicious spicules (often forming glassy tufts).
[Image 6]
Canal system either syconoid or simple leuconoid (a network of chambers) type. Possibly, the ‘leucon type’ term stems from the fact that one ‘flagellated chamber’ of the complicated canal system seems to represent one simple individual of ‘Leucosolenia’. This system presents three successive grades viz.,
Eurypylous type: [Gk. eurys = broad, wide + pyle = gate, opening] i.e., the flagellated chambers communicate directly by ‘broad’ apopyles with the excurrent canals.
Aphodal type: [Gk. aphodos = departure; ‘suffix’ *hodos (oudos) = a way, a course of conduct; general term for a through fare to get from one place to another]; the possible explanation of the term ‘Aphodal’ is that ‘apopyle’ is drawn out as a narrow canal called ‘aphodus’, connecting the flagellated chambers with the excurrent canals and likewise draining the current of water towards outside.
Diplodal type: [Gk. diplo = double + *hodos (oudos) = a way, a course of conduct; general term for a through fare to get from one place to another] i.e., there are two narrow ducts drawn out from the apopylar and prosopylar ends of the flagellated chambers, an ‘aphodus’ connecting the flagellated chambers with the excurrent canals and the ‘prosodus’ [Gk. prosodos = approach, procession; ‘prosopyle’ drawn out as a duct] connecting the incurrent canals and flagellated chambers.
The course of water current in Leuconoid type of canal system is as follows:
[Image 10]
The meanings of ‘aphodos’ and ‘prosodos’ are themselves appropriate i.e., ‘aphodus’ is the site of taking away (departure) and ‘prosodus’ is the site of ‘approaching’ water current; and also coherent with the meanings of ‘apopyle’ (Gk. apos = away from + pyle = gate, opening) and ‘prosopyle’(Gk. pros = near + pyle = gate, opening).
*[Gk. hodos (oudos) = a way, a course of conduct; general term for a through fare to get from one place to another].
Order: Hexasterophora:
[Gk. hex or hexa = six + aster = star + phoros, pherein or Latin ferre = to bear or to carry]
The sponges having trixon six-rayed, star-like (= hexaster) silicious spicules;
as exemplified by Euplectella [Gk. euplektos = well plaited; eu = true or well + plektos or plekein = plaited][Images].
[Image 11]
It is the elegant, most beautiful, gleaming white, glassy sponge with a lattice work (‘plaited’) formed by interwoven 4- or 6-rayed silicious spicules, joined end to end; the body fastened at sea bottom by a tuft of long spicules. It exhibits a commensal association with some shrimp species when they happen to enter into the body of the sponge at larval stage but unable to escape after becoming adult males or females; hence compelled to lead entire life inside the sponge, feeding on the microscopic food particles coming in with the ingressing water current. The sponge with imprisoned shrimps (deep-sea love story) makes a good wedding gift in Japan, symbolizing the romantic idea ‘till death do us part’. Commonly known as ‘Venus’s flower basket’ owing to its growth as ‘cornucopia’ (= an ornamental container shaped like a goat’s horn).
[Planet Venus is the symbol of ‘female’; the name Venus also coming from Roman Goddess of love and beauty, the Greek equivalent of Aphrodite, because of the planet’s luminous jewel-like appearance].
Order: Amphiodiscophora:
[Gk. Gk. amphi = two, both, on both sides + diskos = disk, quoit, platter + phoros, pherein or Latin ferre = to bear or to carry].
[Image 12]
Sponges with amphidisc spicules, with a convex disc on both the ends, bearing backwardly directed marginal teeth; as exemplified by a marine sponge, the Hyalonema [Gk. hyalos = glass + nema = thread][Images], elevated from the substratum by a stalk-like root-tuft, often spirally twisted like a rope [hence, the common name ‘glass rope sponge’], made of a bundle of very long monoactine silicious spicules.
- Class: Demospongiae:
[Gk. demos = the people, population + spongos = sponge] i.e., sponges found in groups like humans or named after Latin Demospongiae because the Class includes ‘the great majority of sponges’ (80.0 – 90.0 % of all sponges; rest 10.0 – 20.0% represented by Calcarea and Hexactinellida). Canal system Leuconoid type (flagellated cells shifted more deeper into flagellated chambers).
Subclass: Tetractinellida
[Gk. tetra = four + + actis = ray + eidos = shape or form] i.e., the sponges with 4-rayed silicious spicules (or some without spicules).
[Image 13]
Order: Myxospongida:
[Gk. myxa = mucus, slime + spongos = sponge + eidos = shape or form; the word ‘myxa’ is often compred with Latin ‘mucor’, meaning thereby ‘mucous substance, mustiness or mold’]; the sponges belonging to this Order, as exemplifies by Oscarella [Images], are commonly called as ‘slime sponges’, forming slimy thick layer of soft gelatinous consistency with velvety surface on rocks, stones or sea-weeds, owing to the absence of spicules or sponging fibres.
Order: Carnosa:
[Latin carnosus (carne) = meat, flesh + German –ose or –osis = a condition, an action, a process]
They include amorphous marine sponges, growing as flat or bulbous benthic communities, appearing like a piece of flesh or liver due to upper surface dark-brown to walnut-brown or beige, often mottled; may also paler from the darkened regions of caves; as exemplified by Chondrilla sp. commonly called ‘chicken-liver sponge’ [the shape and slick surface of the sponge strikingly resembling chicken liver][Images].
Order: Astrophorida (= Choristida):
[Gk. astro = star + phoros, pherein or Latin ferre = to bear or to carry + eidos = shape or form].
The sponges with ‘astrose microscleres’. The megascleres are tetractines (tetraxones), found in combination with oxeotes(monaxon spicules rounded at one end and pointed on the other). ‘Astrophorida’ explains a ‘radiate skeleton’ of coarse texture and a type of skeleton where the structural elements diverge from a central region is called ‘choristid’, hence the alternative name ‘Choristida’; as exemplified by a deep-sea massive sponge Geodia sp. [Images].from the North Atlantic Ocean, commonly named as ‘football sponge’ owing to high density of astrose silicious microscleres.
Subclass: Monaxonida:
[Gk. mono = one + axon = axis + eidos = shape or form]
The sponges with silicious monoaxonic megascleres and with or without spongin fibres.
Order: Hadromerina or Astromonaxonellida:
[Gk. hadros = thick, bulky, strong + marina (or *merina) = sea]
[Gk. astro = star + mono = one + axon = axis + eidos = shape or form]
*[According to an explanation from United states, the name ‘merina’ means ‘grass seed’ or it is a variant of the name ‘Marina’ of Australian origin]
The meaning Hadromerina comes out to be, ‘the encrusting, massive (covering an area up to several m2), spherical or stalked sponges’, common to all seas from the intertidal zone up to the depths of about 4,000 m.
The alternative name Astromonaxonellida refers to the presence of ‘aster-like microscleres’ along with ‘diactine’ megascleres and intracellular collagen fibrils and moderate amounts of spongin fibres, binding megascleres together.
Marine Boring sponges (Cliona, Spirastrella sp.) are prominent examples, the larvae settling on the calcareous substrates (also onto the dead or living corals) and beginning to excavate the substrate(s) by making holes of about 0.5 mm dia. (as if some seed is sown in the soil), using acid to form tunnels in the rock or molluscan shells (especially Ostrea sp.).
[Possible explanation of the word Cliona [Images]: Gk. kleio = the proclaimer; meaning thereby ‘to declare to be an outlaw or evildoer’; as the boring sponges are common in oyster and mussel beds, causing a considerable damage to commercial shell fish farming, besides also making the limestone beds and coral reef frail and fragile].
Order: Halichondrina (= Suberitida):
[Latin halitus / halare / halitosis = breath, bad breath, emiting vapour + chondro = cartilage].
The possible explanation of the word Halichondrina being that they emit a characteristic disaggreable smell (= halitus or halare) similar to that of ‘carbide’ or rotten sea weed and often the surface of the sponge is smooth with a glassy appearance (like a cartilage).
Additionally, they are thickly encrusting with firm consistency, green or yellow, massive or occasionally branching sponges of texture of crumb-of-bread (hence, common name ‘crumb-of-bread sponges’), with volcano-shaped oscular openings and usually 2-rayed megascleres bound together by spongin; as exemplified by Halichondria[Images].
The alternative name of Order, ‘Suberitida’ possibly owes its origin viz., Latin suber = cork oak[evergreen oak tree, Quercus suber] + eidos = shape or form i.e., the sponges with cork-like texture (akin to crumb of bread).
Order: Poecilosclerina:
[Gk. poecilo / poikilos / poikilia = striped, spotted, variegated, dappled with various colours + skleros = hard]
This Order includes deep water marine sponges, having bushy masses, resembling fingers (often joining to form fan-like or drapery-like folded sheets; typically 3.0 mm thick & 30.0 cm dia.) of a wide variety of colours /shades viz., red, blood red or orange-brown, yellow-tan, salmon-red, terra cotta or mustard [some species looking like a patch of red paint]. The soft and velvety surface of the sponges conforms closely to the underlying substrate (the structure of the substrate of rocks or boulders being visible through very thin body of the sponge). The surface is so thin as difficult to scrap off and usually crumbling and tearing off.
[Image 14]
Further, they most typical in having chelae microscleres (C- or S- shaped; sigma-shaped; meniscoid microscleres). The megascleres are bound together by spongin fibres. In the juveniles the skeleton in hemidesmoid i.e., the skeleton of encrusting sponge where monopactine megascleres are arranged singly with heads fixed to a basal plate of sponging and the pointed end directed outwards. The oscules are situated over slightly raised transparent rims; as exemplified by:
Clathria (=Microciona) [Images], the Generic name, possibly derived from the Latin clathratus or clatratus, meaning thereby, ‘with bars, latticed’. Microciona derived from Gk. micros = small + kion = column i.e., small columns (bars = spicules) forming ‘lattice’ with spongin.
Order: Haplosclerina:
[Gk. haploos = single + skleros = hard + ina = denoting names of plant and animal groups].
Sponges with main skeleton partially or entirely composed of diactinal (2-rayed) megascleres, bonded together with collagenous spongin or enclosed within sponging fibres. Microscleres are usually absent; as exemplified by Chalina [Images]and Spongilla [Images].
Chalina, is a name of Spanish origin, given to baby girls, signifying ‘charming and beautiful’. In the common name, ‘Mermaid’s glove’, the * ‘Mermaid’ signifies a ‘mythical sea creature with the head and trunk of a woman and the tail of a fish; conventionally depicted as ‘beautiful’ and with long flown golden hair; and ‘glove’ on account of its shape like a hand with finger-like projections/cylinders. Another common name **‘dead-man’s fingers’ or ‘finger sponge’ is given to Chalina or related (Syringella) species owing to their resemblance with fingers of a dead human being [appearing pale-white, wrinkled and hanging].
Another explanation found for Chalina, is possibly from the Greek word chalinos, meaning thereby, ‘bridle’, strap or scarf (clothing) [not exactly defining Chalina, except relating to somebody ‘bridal’ (man or woman !!).
*Mermayde means ‘maid of the sea’ derived from Middle English word ‘mere’ = sea or lake and ‘maid’ (a shortened form of ‘maiden’ = young unmarried woman).
**Other organisms known as ‘dead man’s fingers’:
Curiously enough, there are other living beings – earning the common name as ‘dead man’s fingers’. One of them is a green alga (Chlorophyceae) Codium fragile (also named ‘green sea fingers’) for its swollen, finger-shaped branches, floating in water or hanging down from the rocky cliffs.
The other one is an animal belonging to Phylum – Cnidaria (Coelenterata), the soft coral (Class – Anthozoa), Alcyonium digitatum, owing to finger-like (hence, the name of species, ‘digitatum’) clumps of coral polyps.
Spongilla:
[New Latin diminutive of spongia = a sponge + -illa = that, the well known, those].
‘That’, which is a silicious freshwater ‘sponge’ of green colour [due to symbiotic algae zoochlorella] growing on submerged objects may be plants, twigs, rocks or logs. Spicules are largely monaxon mega- or microscleres, the former held together by spongin whereas the latter embedded in the cells. ‘Gemmules’ [L. gemma = bud; internal buds] are the chief agency of skipping the harsh environmental conditions [of summers] and germinating after winters are over [a mode of asexual reproduction].
[Image 15]
Subclass: Keratosa:
[German keratose, Greek kerat-, keras = horn + German –ose or –osis = a condition, an action, a process].
Literally, the sponges are famous as ‘horny sponges’, owing to the exclusive presence of a skeleton of sulphur-containing ‘spongin’ fibres [akin to fibrous, horny protein of nails, hair, horn or hoof ; the ‘keratin’]. Spicules are absent; as exemplified by Euspongia (= Spongia), Ircinia(= Hircinia) [Images]etc.
[Image 16]
Euspongia [Gk. eu = true, well + sponges = sponge] is a well-known sponge of ‘industrial’ importance. Its literal meaning comes out to be ‘true sponges’ in the sense of fulfilling the conditions of defining a sponge ‘animals well known for their ability to absorb and withhold fluids’ (a quality to suck in or imbibe).
Familiar ‘bath sponge’ (Euspongia) of household (used for sponging and scrubbing the body) consists only of ‘spongin skeleton’ and its capacity of holding water is due to capillary forces of the meshes of ‘spongin’ reticulum. The best quality ‘bath sponges’ are abundant in the Mediterranean, Gulf of Mexico off Florida coast and waters around West Indies and Australia. Tarpons Springs in Florida is the best commercial sponge-fishing centre of US, where million dollars worth of sponges are collected for the ‘sponge industry’ per annum.
OTHER TECHNICAL TERMS TO KNOW !!!
Amoebocytes: [Gk. amoibeand modern Latin Amoeba = change or alteration + cyton/ kytos = cell, box, hollow vessel] i.e., the cells which are Amoeba-like in structure and working.
Archaeocytes: [Latin ‘arch’(ae/i) = ancient, first, beginning or primitive; Gk. archaios = beginning + cyton/ kytos = cell, box, hollow vessel] i.e., undifferentiated first cells (= embryonic); aptly called ‘totipotent’ cells i.e., having ‘total or complete potential’ of giving rise to any other cell within the animal, including germ cells.
Collencytes: [Gk. koll = glue + cyton/ kytos = cell, box, hollow vessel] i.e., the cells which are ‘glued’ together (due to branching pseudopodia) to form syncytial [Gk. syn = together + kytos = box, hollow vessel] network [a multinucleate mass of cytoplasm resulting from fusion of cells].
Thesocytes: [Gk. thesos / thesis = deposit + cyton/ kytos = cell, box, hollow vessel] i.e., the cells with deposits of food reserves.
Myocytes:[Gk. mys = muscle + cyton/ kytos = cell, box, hollow vessel] i.e., the cells which have muscles-like property of contraction and relaxation; present around ostia or oscula to regulate the diameter of the opening.
Porocytes: [Latin porus = pore + cyton/ kytos = cell, box, hollow vessel] i.e., large tubular (porous) cells, aligned with the body wall of certain sponges like Leucosolenia.
Trophocytes: [Gk. trophos = nutrition + cyton/ kytos = cell, box, hollow vessel] i.e., the cells which are destined to provide nutrition for the animal.
Scleroblasts: [Gk. skleros = hard + blastos = embryonic cell, germ, a bud or a sprout] i.e., the embryonic cell differentiating into a skeletal structure e.g., calcoblast (calcareous spicule forming cell), silicoblast (silicious spicule forming cell) or spongioblast (sponging fibre forming cell).
Monoecious: [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 = hermaphroditos; 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 Gods; 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.
Protogyny: [Gk. pro = before + gyno = female] i.e., a condition when the female organs mature prior to male organs in a hermaphrodite.
Protandrous: [Gk. pro = before + andros = male] i.e., a condition when the male organs mature prior to female organs in a hermaphrodite.
Micromeres: [Gk. micros = small + meros = part /segment] i.e., a term used to describe small-sized cells (blastomeres) of an early embryo (blastula).
Macromeres (Megameres): [Gk. macros / megas = large + meros = part /segment] i.e., a term used to describe large-sized cells (blastomeres) of an early embryo (blastula).
Blastula: [Gk. blastos = embryonic cell, germ, a bud or a sprout + *-ula], an early developmental stage after a ‘mulberry-like’ ‘ball of cells’ stage called ‘morula’ [L. mor (um) = mulberry + *-ula] consisting of a single, layer of cells enclosing a central cavity (blastocoel).
Stomoblastula: [Gk. stoma = mouth + blastos = embryonic cell, germ, a bud or a sprout + *-ula] i.e., a kind of blastula having an opening or mouth.
Amphiblastula: [Gk. amphi (– ambi) = two, both, on both sides + blastos = embryonic cell, germ, a bud or a sprout + *-ula], a larval stage after ‘stomoblastula’, having 2 halves of flagellated and non-flagellated cells, representing ‘two (both) germ’ layers i.e., one (ectodermal) destined to give rise to dermal epithelium (the descendent of non-flagellated cells) and the other (endodermal) to inner choanoderm (the descendent of flagellated cells).
Gastrula: [Gk. gaster, gastr- = stomach + *-ula], a larval stage, developing after blastula stage with a larval gut, the archenteron [Gk. arch = first + enteron = gut] and 3 primary germ layers (ectoderm, endoderm and mesoderm).
*-ula or L. ulus , –ule = used as a suffix denoting a larval or developmental stage as modeled by Earnst Haeckel while devising the term ‘planula’ (a larva of Cnidarians/Coelenterates).
or
A diminutive suffix occurring in the Nouns of Latin origin (e.g., granule).
ECONOMIC IMPORTANCE OF SPONGES
Though unpalatable due to unpleasant taste, odour and prickly nature, the sponges are utilized as food by some Molluscs (Nudibranchs) [Images] and fishes (Angel Fishes) [Images]. Besides, they have been important from other points of view, also viz., acting as commensals and commercial commodities, may be bath sponges or sources of some natural therapeutic compounds.
Commensalism and natural therapeutic compounds are the chief points of interest here:
COMMENSALS
Being mostly unpalatable, sponges serve as secure houses for a great number of worms, Crustaceans, Molluscs, small fishes etc. Certain Crabs deliberately pick up and attach pieces of sponges to their legs and carapace. After a considerable growth, the Crab remains completely camouflaged and concealed under the sponge cover. Similarly, the sponge named Suberites [Images] (a relative of Cliona) frequently grows on the snail shells occupied by ‘Hermit Crabs’ [Images]. After the shell is completely riddled by the sponge, the ‘Crab’ now comes to live inside the cavity of the sponge itself, the latter now deriving the benefit of being transported from one place to the other.
Sponge as ‘CHARITABLE HOTELS’:
Sponges play a great ecological role in their natural habitat by providing a ‘home’ for a wide variety of microscopic or macroscopic organisms. The porous nature of sponges makes them ideally suited as ‘biological boarding houses’ or ‘charitable hotels’ providing free protection and food, thus presenting a unique example of commensalism. A massive sponge called *‘loggerhead sponge’ (Spheciospongia vesparium) [Images], native to the Caribbean Sea and around the coasts of Bahamas and Florida has been found to be a favourite home for a wide variety of animals, living in the tunnels and cavities (= leuconoid type of canal system) of the sponge. Along the coasts of West Indies and Florida this sponge has been found attaining a weight of more than 300 kg. Though highly toxic to many fish, this sponge forms the diet of certain ‘angelfish’ and also for ‘hawksbill sea turtle’[Images] (Eretmochelys imbricata), consuming as much as 544 kg of sponge in a year.
Once, with a view to observe the diversity of animals living in association with the *‘loggerhead sponge’, A.S. Pearse (1877 – 1956), a well-known Ecologist/Botanist/Zoologist form Crete Nebraska (United States), collected a specimen of about the size of a 200 l drum. He counted and classified all the organisms found living inside; and to anybody’s surprise, a total of about 17,128 animals were recovered, of which 16,000 were only Alphaeid shrimps (3.0 – 5.0 cm), but other kinds of animals were also found viz., small fishes, lobsters, Crabs, brittle stars etc.
*loggerhead = a thick-headed or stupid person, blockhead.
The name ‘loggerhead’ associated with the sponge is possibly after ‘loggerhead sea turtle’ (Caretta caretta) [Images]of Atlantic, Pacific and Indian Oceans, having a disproportionately large head and growing up to about 90.0 cm (135 – 545 kg).
NATURAL THERAPEUTIC PRODUCTS FROM SPONGES
Often the phrase ‘marine sponges, a gold mine’ is used owing to fact that they have been found rich source of a wide variety of vital, diverse, bioactive compounds viz., alkaloids, terpenoids, sterols, macrolides etc. In this context a special mention may be made of an ‘anticancer’ drug, ‘eribulinmesylate’ or ‘Halichondrin – B’, isolated from the marine sponge Halichondria okadai.
A number of studies have found antibacterial, antifungal, antiviral (Anti- SARS and Ebola), anti-inflammatory and immunosuppressive activities in the crude extracts of marine sponges.
POISONOUS SPONGES
Please refer to ‘Animal poison and poisonous Animals’ on the home page or click on ‘VP art 5’.
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