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III.GENERALPART
1.Generalcharacteristicsofrotifers
Rotifersareverysmallanimalsthatpossessnumerousunusualcharacteristics,
averydiversemorphology,andacomplexanatomy.Astheyoccurinsomany
formsandshapes,itisjustifiabletocallthem“Nature’sgems”andtocomparethem
tobutterfliesandbirds(DONNER1973).POURRIOTandFRANCEZ(1986)claimthat
rotifersarebeautiful,occasionallywhimsical,andalwaysfascinating.Theymost
oftenrangeinsizefrom0.1to0.6mm,growingoccasionallyto3.00mm.Their
bodyisnotsegmented;itisbilateralandhasthepseudocoel,i.e.,thebodycavity
lackingitsownepitheliumandcorrespondingtotheschizocoel.Rotifergrowth
involvesthegrowthofindividualcellsordorsalseparationofcells;itisallometric
(non-uniform);androtifersgrowveryfast,occasionallydoublinginsizeduring
theinitial24hoftheirlife(EjSmONT-KARABINetal.1993).Thediversityofrotifer
shapesandformsisstillmoreoutstandingwhenonerealisesthat,likeinnematodes,
thenumberofrotifercellsislowandconstant(eutely)throughoutthelifespan.
Althougharelativelysmallgroupofanimals,theirveryhighproductionrenders
themextremelyimportantplayersininlandwaterenvironments.Thankstotheir
adaptiveabilities,rotifershavecolonisedalmostallaquatichabitats:theyarepres-
entincoastalwatersoftheseas(withupto50species);inlakes,ponds,andepisodic
pools;amongwetplants(e.g.,mosses),andinmoistsoil;theymayalsoparasitise
variousinvertebrates.Rotifersmayoccuratenormousabundances.Pollutedponds
andlakesmaysupportupto20,000individuals/dm3water(BIELAńSKA-GRAjNERand
mAjEWSKA1994),anUpperSilesianbellpitsupporting>>25,000individuals/dm3
(BIELAńSKA-GRAjNERandNIESLER2002).Thehighestrotiferabundances(inexcess
of100,000individuals/dm3)havebeensofarreportedfromAfricanlakes(NOGRADY
1983),whilecommercialculturesinIsraelproduceabundancesfrom50,000to
500,000individuals/dm3(LUBZENS1987;LUBZENSetal.1989).
2.Theoriginofrotifers
AllearlytheoriesconcerningtheoriginofRotifera,foundintextbookswrit-
tenbeforetheintroductionofmodernphylogenybasedonthecladisticsystem
ofHENNIG(1953,1965),areofhistoricalsignificance.Accordingtothecladistic
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