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Foot.Thefootispresentinmostrotifers,althoughrelativelynumerousspe-
cies,e.g.,thoseofthegeneraAsplanchna,Polyarthra,andAnuraeopsislackit
altogether.Theborderbetweenthetrunkandthefootismarkedbythecloaca.
Thefootusuallyhastwotoes(occasionallyfusedalongashorterorlongersec-
tion);sometimesasingletoeispresent.Thetoesofsomespeciesareidentical
insize,whileinotherstheymaysubstantiallydifferinlength.Thetoebasemay
bearcharacteristicsetae,likethoseseenin,e.g.,Trichocerca.Insteadofthetoes,
thegenusTestudinellahasatuftofcilia,whichoccuralsoinrotiferlarvaeand
males.Thefootshapedependsonitsadaptationstoleaping,creeping,steeringor
attachmenttothesubstrate.Thefootcontainscement(pedal)glandswhichmay
bereducedormayoccurinarudimentaryform.Sessilerotifersusethecement
glandsecretionasameansofattachment;frequentlythesecretionisobserved
tobetrailingbehindarotiferasalongfilament.Thesecretionisalsousedto
attachtheeggstotherotiferbody.Natant(swimming)rotifersmayusethefoot
forsteering.Thefootandtoesofsomespeciesareprovidedwithstrongmuscles
whichenabletherotifertoleapwhenchasingprey(Monommata,Scaridium,
Eudactylota)(Fig.8).Thestronglytactilefootofsessilerotifersmayretract
thebodyintothelorica.Incolonialforms,thefeetplayanimportantpartby
connectingindividualsintoacolonywiththepedalglandsecretion(mucusor
gelatinoussubstances).
Alimentarytractandmouthparts(trophi).Thealimentarytractbegins
withthemouthlocatedanteriorlyontheventralsideofthebody.Themouthopens
intoafunnel-likestructure,thebuccalcavity,whichleadstothepharynx(mastax).
Itisdistinctbybeingequippedwithaspecialjaw-likeorgancalledthetrophi.
Inaddition,salivaryglandsopenintothemastax.Thepharynxisfollowedby
anarrowoesophagusleadingtoalargestomach.Pastthestomachthereisashort
intestinewhichopensintothecloacasituatedonthedorsalside,terminallyon
thetrunk(Figs.1,9).
Duetotheirhighmorphologicaldiversity,thetrophiinsidethemastaxareof
akeytaxonomicimportance.Themastaxisthemostmuscularisedpartoftheal-
imentarytract,thetrophibeingsituatedinitscentre(Figs1,10).Thesalivary
glands,whichproducemucousanddigestivesecretions,openintotheposterior
partofthemastax.Thepharynxisconnectedwithabroadenedmid-gutcalled
thestomach.Itsupperpartreceivesthesecretionoftwo(moreseldomfour)gastric
glands,theso-calledpancreaticglands,whichproducesubstancesdecomposing
thefood.Insessilerotifersthecloacaoccursanteriorlyonthebody,thealimentary
tractbeinghorseshoe-shaped.Thealimentarytractinsomespeciesthatingest
liquidfoodisblind-ended.
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