Adaptable Defense: A Nudibranch Mucus Inhibits Nematocyst Discharge and Changes With Prey Type

2004·3.7 MB·English

by  Paul G Greenwood

Reference:Biol.Bull.206: 113-120.(April2004)
2004MarineBiologicalLaboratory
Adaptable Defense: A Nudibranch Mucus Inhibits
Nematocyst Discharge and Changes With Prey Type
PAUL G. GREENWOOD*. KYLE GARRY, APRIL HUNTER, AND MIRANDA JENNINGS
Colby College, DepartmentofBiology. 5732MayflowerHill. Waren'ilie. Maine 04901
Abstract. Nudibranchs that feed on cnidarians must de- 1973. 1986; Conklin and Mariscal. 1977). Defenses that
fend themselves from the prey's nematocysts or risk their might protect aeolids from nematocysts include behaviors
owninjury ordeath. Whilea nudibranch's mucushasbeen that limitcontactofthe nudibranch with the prey (Grosve-
thoughttoprotecttheanimalfromnematocystdischarge,an nor. 1903). morphological adaptations such as ellipsoid
inhibitionofdischargebynudibranchmucushasneverbeen vacuolatecellsoftheepithelium(Graham. 1938;Porterand
shown.Thecurrentstudyinvestigatedwhethermucusfrom Rivera, 1980; Martin and Walther. 2003) or a cuticle that
the aeolid nudibranch Aeolidia papillosa would inhibit linesthe mouthregionofthe nudibranch(Edmunds. 1966),
nematocyst discharge from four species of sea anemone and copious mucous secretions (Graham, 1938; Russell,
prey. Sea anemone tentacles were contacted with mucus- 1942; Edmunds, 1966).
coatedgelatin probes, and nematocystdischarge wasquan- It has been hypothesized for over a century that the
tified and compared with control probes of gelatin only. nudibranch's mucus serves as a protective barrier against
Mucus fromA. papillosa inhibited the discharge ofnema- nematocysts (Boutan, 1898). Grosvenor (1903) suggested
tocysts from sea anemone tentacles. This inhibition was thatthere mightbe some acclimatization tonematocystsas
bcsBsnnprhiueeeaamdmccnnpiaaicglbtfuheyriosscdaceab,nylaecslpotchtypfhoaehmdrltaiieihmmsdnenuictgcthlbieuaynecdrstoepgianrtemctooaehfdtodaeteufenhcidegnateiehsnaaedtsgnnho.ecenewiimWmeiatnoowhthhnniieioeenpbnnrimte2sbtoyuphreweceytcesuiwpemspeeekurcsesedicneyuuostrsn.oimsnporiTwgeasnchhthtfihieieeebceasrihndettuiowhdnlttaaigihhs-.ndee eccp"aiaydhnersayosttpp.uteodgrfiHht-shotvcethwihoeespapvcrrmrooeguotuerctes,ecog"cteutinSsmveanuerlducavendlofiailuentbynuisrsr-aaeePnns,lcdeoachbfwtrseheemcatnfuatircuoio(suntm1essw9doc7wtiou2oofpl)fusidelporehduebcynseiptifomunicthcnunihncibpeeidursctaesieyrzsn.iwesaeadCanmsorasynttnphkooeat---tot
ctniououdnli,dbarnhadnacvhleisfeaahnsidisgtntoihrfeyiicroanfptrtehiye,mpnaauncdtiabdoranapntctahhbesl.ebemhuacviuosr,prdoitsetcrtiiboun- oSlipnnuersainldlduarMniaenragipsotchlaeiltfain(rsa1t9w7fa7e)swanmpoiptnaeurdetnettshlayotfsttfhueenegdaiebnoygliitdbsutpnrutedhyiebarnnauendmci-h-
branchs' behaviorindicatedthat nematocystdischargethen
ceased. Theseauthors hypothesizedthat aeolids might pro-
Introduction
duce oracquire (from the prey) a substance that prevented
All predators must overcome their prey's defenses to nematocyst discharge. Recently Mauch and Elliott (1997)
feed.Inthecaseofnudibranchsthatfeedoncnidarians,the foundthatmucusfromtheaeolidnudibranchAeolidiapap-
predatormustdefend itselffrom theprey's nematocystsor illosa caused fewer nematocysts to discharge from its po-
risk its own injury or death (Harris, 1973; Conklin and tential prey, the sea anemone Anthopleiira elegantissima.
Mariscal, 1977).Nematocystsfromnon-preycnidarianscan than mucus from other gastropods did. Mauch and Elliott
killthenudibranch(Grosvenor, 1903);eventhepreyspecies (1997)hypothesized that the nudibranchsmightadapt their
can be dangerous ifthe individual is large enough (Harris, mucus as protection from their cnidarian prey, but the
nudibranch mucus was tested on only one species ofcni-
darian.
Received2July2002;accepted21 January2004.
*To whom correspondence should he addressed. E-mail: Whileafew nudibranchsarehighly specializedandfeed
[email protected] exclusively on one prey species, most nudibranch species
114 P. G. GREENWOOD ETAL
canfeedonseveraldifferentpreyspecies(Thompson, 1976; ing commercial fishing dock in Portsmouth, New Hamp-
Todd el ni, 2001). Monophagous species might have de- shire. Individuals of A. papillosa and the sea anemones
fensive mucusthatworkswell againstthenematocystsofa UrticinafeliiuiandAiilnctinicistellawerecollectedmidway
singleprey species,butthe moregeneralistfeedersneedan throughthelittoralzoneonbedrockatwestQuoddyHeadin
effective defense against a number of cnidarian species Lubec, Maine (courtesy ofC. Sisson). Twelve individuals
(with different nematocyst types). Such nudibranchs might ofA. papillosa, living among individuals ofthe sea anem-
requiredefensive mucusthatchangespropertiesdepending oneAnthopleuraele^antissima, werecollectedfromthelow
upon which prey is beingconsumed. intertidal zone on the coast ofCalifornia (supplied by Pa-
The current study investigated whether mucus from the cific Biomarine Supply, Venice, CA). Individuals of A.
aeolid nudibranch Aeolidia papiltoxa inhibited nematocyst ele^iintissiimiwerecollectedfromthelowintertidalzoneof
dischargefromdifferentseaanemone species,andwhether SanJuan Island.Washington (courtesyofD. Duggins). All
the inhibitory nature ofthe mucus changed when the prey animalswerekeptinrefrigeratedaquariawithrecirculating
species was changed. Individuals ofA. papillosa feed al- and refiltered seawater (11 C, 319rr salinity, pH 8.2) col-
mostexclusively on seaanemones (Hall andTodd, 1986). lectedattheDarlingLaboratory,UniversityofMaine,Wai-
In its New England subtidal habitat. A. papillosa is fre- pole, Maine. Anemones were kept in separate plastic or
quently found among populations of the sea anemone glass containers within the aquaria, and the nudibranchs
Metridiiun.senile,butisalsofoundassociatedwithavariety were placed in separate acrylic plastic containers, segre-
ofother sea anemone species (Harris, 1973; Reidy, 1996). gated according to the sea anemone species on which they
Individuals of A. papillosa have been induced to change were feeding. Sea anemones were fed frozen brine shrimp
prey species in the laboratory (Hall et ai, 1982; Hall and every 2 days, and the nudibranchs were fed sea anemones
Todd, 1984, 1986),butinthefieldasinglepreyspeciesmay adlibidinn.Theseaanemonesthatwereusedaspreyallhad
dominate a large area. Concentrated prey distribution and pedal disk diameters less than 3 cm. and the nudibranchs
lownudibranchmobilitymeansthatindividual nudibranchs rangedinlengthfrom 1 cmto7cm.IndividualsofM.senile
mightspend mostoftheirlivesclosely associatedwithjust wereheldfornomorethan2monthsbeforebeingreplaced
onepreyspecies(Harris, 1973, 1987;Todd, 1983). Because withotheranimals;theotherspeciesofseaanemoneswere
of this intimate association between A. papillosa and its held for less than a month.
prey, protection from the prey's nematocysts has a signifi-
cantimpactonthebehavior,distribution,andlifehistoryof Controlprobes, mucus-coatedprobes, andgeneral
theWneuduisberdanmchu.cus-coatedgelatin probes in a highly repro- probing ofsea anemone tentacles
ducible method (Watson and Hudson. 1994) to investigate Weusedgelatinprobestoquantifynematocystdischarge
theeffectsofA. pctpillosa mucuson nematocystdischarge. from tentacles ofsea anemones. Each probe was made by
When gelatin probesaretouched to seaanemonetentacles, coating one end ofa 6-cm length of monofilament fishing
nematocysts thatdischarge intothegelatin remainattached line (Stren. 6-lb-test or 17-lb-test) with 25r/c (weight/vol-
totheprobeandareeasilycounted(Watsonand Hessinger, ume) gelatin in E-pure deionized water (modified slightly
1989; Watson ct til.. 1999). In this study, mucus-coated from Watson and Hudson, 1994). Occasionally, the gelatin
gelatin probes were used to mimic the contact ofa nudi- did not adhere well to the probe, and such probes were
branchtothe seaanemones. Wealsoprobedseaanemones discarded. The gelatin adhered betterto the 17-lb-test line
in the presence of N-acetylneuraminic acid (NANA). thantothe6-lb-testline,sothenumberofprobesdiscarded
NANA, which mimics the complex molecules containing was smaller when the heavier line was used, as it indeed
N-acetylatedsugarscommonly foundontheseaanemones' was.inlaterexperiments.Probesthatwerecoatedwithonly
normal prey (Thorington and Hessinger. 1988). has been gelatin served as controls.
found ID increase the sensitivity of sea anemone nemato- Toprepare anexperimental mucus-coated probe, a nudi-
c\tesinmechanical stimulation(ThoringtonandHessinger. branchwasremovedfromthewaterandagelatinprobewas
1988. 1990. 1998; Watson and Hessinger. 1994). With gently wiped across its dorsal surface (from anterior to
NANA. we can therefore determine whether nudibranch posterior) four times. Three mucus-coated probes were
mucus actually inhibits nematocyst discharge or simply made from each nudibranch. Anemones that had not been
provides no stimulus fordischarge. fedforbetween24and36hswereplacedintoseparateglass
dishes that contained a probing solution of cither filtered
Materials and Methods seawater alone, or filtered seawater and NANA. Ten min-
Aniiiiiil collection andmaintenance utitoens,aeftaecrhthdeisahnewmaosnepslacweedreunpdlearcedaninOtolytmhepupsrobSiCn3g0sosltue--
Individuals ofthe nudibranchAeolidiapupillnxii and the reomicroscope. and probing began with the edge ot the
sea anemone Mciriilimn senile werecollected from a float- probe tipbeing lightly touched toone tentacle about 5 mm
SEA SLUG MUCUS INHIBITS NEMATOCYSTS 115
proximal tothetentacletip. Threecontrol probesandthree species. Because the baseline number of nematocysts dif-
experimental probes, all prepared from the same nudi- feredbetweenthetwoseaanemonespecies,thesedatawere
branch, were used to probe each anemone. Used probes converted to relative values, where a relative value of 1.0
werefixedin2.5%glutaraldehydeinfilteredseawaterforat represents the average number of nematocysts discharged
least30sandthenplacedinto3dropsofdeionizedwateron into control probes. Data collected from mucus-coated
a microscope slide. Individual nematocysts that had dis- probes foreach day were converted to an average relative
charged into the gelatin were counted, using an Olympus discharge based on controls for that day from the same
CK2 inverted phase contrast microscope equipped with a anemones. Results fromtestsoneach seaanemone species
40X objectivelens. Inearlyexperimentswith probesmade were analyzed by ANOVA and with Scheffe's test for
from 6-Ib-test monofilament line, we counted nematocyst pairwise comparisons.
capsulesfromatleastthreefieldsofview,andthemeanwas
calculated for each probe. In later experiments, when we Ifa secondpreyspecies isoffered, willthe effectofthe
usedprobesmadefrom 17-lb-test line,the nematocystcap- mtdihranch mucuson neiuatoc\st discharge change?
sules from one central field ofview were counted. Using
tnheemsaetotceychsntisquoens,eabcehtwpereobne7w5e%reancdoun1t0e0d%,'aonfdthbeotdhistcyhpaersgeodf tooneFteoMsut.rnsieenmndiailtveoidcfuyoasrlts21doitdsacAy.hsa.pragMpeuiclflurosos-macofwaeeterededinfgperdotebtnehtesacswleeearseaonfuesMme.-d
probes yielded highly reproducible results. senileandtheseaanemoneAnthopleuraelegantissima. The
Doesa midibrunch's mucus inhibitthe nematocyst nudibranchs were then offered both M. senile and Antho-
dischargefrom the tentaclesofitspreyspecies? pfloeuunrdaoneletghaentciosassitmao.f NAnetwhopEnlgeluarnad,elseogatnhteisesxipmearimisentnaolt
Probes were coated with mucus from 12 individuals of nudibranchs could not have encountered this prey species
Aeolidiapapillosaofmixed sizesthathad been feedingon before.Fourteendayslater,mucus-coatedprobeswereused
the sea anemoneMetridium senile and with mucus from 6 to test nematocyst discharge from the tentacles of both
individuals of A. papillosa of mixed sizes that had been species ofprey anemone. Data were converted to relative
feeding on the seaanemone Urticinafelina. These mucus- discharge values as described for the previous experiment
coated probes were then used to probe feeding tentacles and analyzed using Student's t tests.
from the seaanemonesM. senile, U.felina, andAiilactinia
Stella. Ineachexperiment,oneanemonewasalwaystested Does the nudibranchproduce its own inhibitorymucusor
withthreecontrolprobesandthen,immediatelyafterwards. simplvbecome coveredin theprev's mucus?
wiimetnhtatlhreperoebxepserwiemreentcaolat(emducwuist-hcomautceuds)fprroobmesa;ntihnedievxipdeural- Any inhibitory effectofthe nudibranch's mucuscoating
betctnwnhhrqiueoeeautdmmnahiapMcltbtahahrodrv.ranicaeennsyerTcc-sihhhntWap.eaenhrsrdmcToiegieabhtessteecngosahercimnaanyyrwedtnsgoaadtUtesnhcmeitdonneenuinsuasstrtamcernenhodwbssalaheplrtoerwygopnenzeorsrecfoeedvaibdalnteuircttosssioeuimacslntnahfumegtcoacuderercuSsgutfsaeeuoswdard-fecgecnrrhrnnoeoeaotammn'rsatudsmpetneaeaoe/dclmcqciiteheuyetpssaasyrt.nltnsou)sabd(Tneiootiods-ofnr ebcwmwwpmoioieieuusguteprccshhlineiutudnbssimgfcilubenoitreoecdtahefdyitua,mivtaesinotdadghwvrrrueeeeewaesoadilumnpstlcocrhtfleovtoeryhmefoamoepndfmu.Aasc.sptrfPaeueherrapecsdoopaimabepanrfesintutrslthedihloedcimawomuutbeoslrirarnainstaerenhhnaoigeccmrfbMhoeied.afgtmoeotibirrereoeessxydndeiageinlninwdioegogilffn.estfs.cuheia4roTzcm5faTetonatushiucevmcededettiuihennsbspaeoittrrsfnfasaofrhtnbttthoaechhoiemsdheesfr
emaicnhimsipzeecitehseoefffaenctesmoofnecapwtaisvittyestoendnweimtahtionc2yswtedeiksschoafrgeit,s wnuadsibthreanncthrainmsfmeerdrieadtteolyfrbesehhifnildtetrheedhseeaarwta.teEra.chStenruidleibcroatntcohn
collection.
swabswereusedtowipethemucusfromthedorsalsurface
/n/u"dthiebrparnecyhsmpeucciuessoisncnheamnagteodc,\switllditshcehaefrfgeectalosfothcehange? saodfedvietthnieotninamluedssi,wbarabansndcwhtehraeendnuusdefidrbotrmoanwtcihhpeewstauhsrernaougudaniidbnirnatgnraccnhesrfaaettraor.teadlSiotxof
Seven specimens of A. papillosa were collected from freshfilteredseawater. Afterthenudibranchwasallowedto
severalNewEnglandlocalitiesandwerefedU.felinafor 16 recover from this treatment for 45 min, additional probes
days in the laboratory. During that period, mucus-coated werecoatedwithmucusfromitsdorsalsurfaceimmediately
probes were used to test nematocyst discharge from the behind the heart. The mucus-coated probes were then all
tentaclesofU.felina andM. senile. Thenudibranchs' prey used to probe feeding tentacles ofM. .senile. Three probes
was then switched from U.felina to M. senile and. over a were coated with mucus from each nudibranch for each
2-week interval, mucus-coated probes were used periodi- treatment(unswabbedandswabbed).Countingofallprobes
cally to test nematocyst discharge from both sea anemone was done blind. The mean number ofdischarged nemato-
116 P. G. GREENWOOD ETAL.
Gelatin probes coated with mucus from the nudibranch
3 50- Controlprobes (6) Aeoliiliupapillosa that hadbeen feedingonM. senileelic-
ited 51% fewer nematocysts to discharge from M. senile
Mucus-coatedprobes than control probes did (Student's / test, tg = 5.1. P -
0co.n0t0a0i6n)ing(F1i(g).~71M). NWAhNeAn.ptrhoebinnugmbwearsofdonneemationcyssetaswattheart
discharged into mucus-coated probes was almost 657r less
than the number that discharged into control probes (Stu-
dent'snest,/,,, = 9.1.P < 0.0001) (Fig. 1),butthemean
number ofdischarges into control probes was higher than
w0.h0e0n3)N.AFNoAr ewaacshoamintetmeodn(eStsupdeecnite'ss,tptresotb,intLg> =in4.110.~P7 M<
NANAelicitedagreaternumberofdischargednematocysts
FSW FSW+NANA than probing in seawater alone (Fig. 2). Statistical results
=
intFoipgruorbees1.coaNteudmbweitrhomfucnuemsatforcoymstisndidviisdcuhaalrsgeodfAienotloulcoinatproalpilplroosbaesthoart Pwer<e0a.s00f3o:llofwosr:AufloarctMi.nisaensitleel.la.StSutduednetn'ts's;/tetsets.t.tf,t2 = 44..15..
hadbeenfeedingonMetridit/nixcnile.Mucus-coatedprobeswereusedto P < 0.05: forAnthopleura elegantissima. Student's /test.
(pNinrFAoSpNbaWAer))etn,eatnnhatednasdcelFsceSsoamWropefactrothenheedtanaisugnemaiaibnnegasrnts1ecCmooTnoft7nraeoMnleMpmN.ro-onasbceeeesnstilyouelfsnegiedenulra(btacoimotnnihtnorinofclliyl.atpecrTriohedbdees(sn)FeuaSmowrbWaettreh+sre tK4FW=h7eM5n.0N.prAPoNbe=As0wc.oa0as0t8eud.sewBdietfchoarumsaulelcuistsubifsncerrqoeumaesnAe.tdpetaxhppeielrrlieomssepanotntssh.ea,t
numbersofnudibranchsused(mucus-coatedprobes)pertest. had been feeding on M. senile were used to probe the sea
anemones UnicinafelinaandAulactiniastella. therewasa
small but nonsignificant increase in nematocyst discharge
cysts into mucus-coated probes from unswabbed nudi- overcontrols (for U.felina. Student's / test, ?,,, = 0.344,
branchswascomparedtonematocystdischargeintomucus- p = o.7(); for Aitlaetinia stella. Student's t test, /2f) =
cporoabteesd.pArnoableyssifsrowmasswdaobnbeebdynAudNiObrVanAchasndanwditihntSochceofnfter'ols 0n.e7m6a.tocPys=ts0d.i4s6c)har(Fgiegd.i3n)t.omAuscubse-focroea,tesdigpnrifoibceasntflryomfetweenr-
test forpairwise comparisons. taclesofM. senilethanintocontrolprobes(Student's;test,
indWiveiduaallssoiinnhviebsittiegdadteidschwahregtehefrrotmheothmeurciunsdivoifduMa.lssoefniMl.e fresli=n=a9w.e0r.ePmo<stl0y.0m0i0cr1o)ba(sFiicg.p-3)m.asNteimgaotpohcoyrsestsanfdrosmomUe.
senileheldin separatecontainers. Individual seaanemones basitrichous isorhizas. Nematocysts from Aulactinia stella
weretransferredtofilteredseawater.allowedtorecoverfor werebasitrichousisorhizasandmicrobasicp-mastigophores
10min,transferredtofreshfilteredseawateragain,allowed in aboutequal numbers. The mucuseffectivenesswassim-
torecoverfor 10mm.and finallytransferredtoadry,clean
glassdish.Theseaanemonesecretedmucusfor 10minand
wasremovedfromthedish.The mucus wasremoved from
thedishandstored insterilemicrocentrifugetubes. Gelatin
probes were placed into the mucus for 2 min and used to
probedifferent individualsofM. .senile. Three probeswere
coated with mucusfromeachoftouranemones.The mean za
number of discharged nematocysts in the mucus-coated U00
probeswascomparedtothat numberincontrol probeswith
no mucus. Data were analy/ed using Student's / tests as Q
described above. Vo-
I
Results 10-
Does a luulihraneli's nu/ens inliihit the neinaloeyst
t!i-,<Inline ti'din the lentaeles ofitsprey species'.' M.senile A.stellu A.elegantissima
When tentacles of the sea anemone Metruliiim senile Ii^uri' 2. Number ol nenutocxsts discharged into control piobes.
dwiesrcehaprrgoebreedspwointshec\\o.nitsrooblseprrvoebdes(Fiing.se1a).wTatheer,neamabtaosceylsitnse ATtneeinnlttiaiacic/llieelsrsioilronloctilhht\ee(r;isiieiinaidii\a.v\niiedimumiaolnwseersoefMecpatrcrohubleisdpueiicnnie.fsvicliwt/eefrr,eedAupslreaaocwbtaeitdneirian(^FFIcSSlWlWa).caaonnndd-
that discharged into the gelatin were mostly basitrichous laining Id 'A/N-acel\lneuraminicacid(FSW+NANA).Thenumbersin
isorhi/us along with some microhasic p-masligophores. parenthesesarethenumbersofanemonesusedpertest.
SEA SLUG MUCUS INHIBITS NEMATOCYSTS 17
nodifferentthan in controls (forM. senile. Student's/test.
CMouncturso-lcopraolbeedsprobes ?thb == 11..1906..PP==0.03.019;8\)\ir(AFiugl.ac4t)i.niastella. Student'sttest,
z
8 Ifthepreyspecies ischanged, willthe effectofthe
I nudibranch mucus on nenuiiocystdischarge also change?
Q SevenindividualsofA.papillosathathadbeencollected
oU from several different New England localities were fed U.
1 felina for 16days in the laboratory. As before, nematocyst
Z3 discharge into mucus-coated probes was 50% less than
nematocystdischarge into control probes for U.felina, but
M.senile A.Stella U.felina not forM. senile (Fig. 5). The nudibranchs' prey was then
switchedfrom U.felinatoM. senile, andoveraperiodof2
Figure3. Numberofnematocystsdischarged intocontrol probesor weeks, the mucus from the nudibranchs wastested period-
ihunsatedodbpteroeonbperfsoebceedoiatntegendtoanwcilMtehsetmorfuicdtuihuesmsfesraeonmialnieenmd(ioSvnDied)su.alMs.MuocsfeuAnsie-loecl,oualAituaeldapcatppirinoliblueossxatwctelhlraae.t tichaelleyxpaegraiimnsetntb,otthhesenaumabneermoonfenespmeactioecsy.sOtvsetrhatthedicsocuhrasregeodf
apanrdedUratgiaciinnsatfceloln/tirnol(inpro1b0e~s7oMfgNe-laactientyolnnlye.urTahmemincumabciedr)sainndpwaerernethceosme-s pinrtoobemduc(uAs-NcOoVatAe,dFpr4o2bIes==in8c.r2e0a,sedP w=he0n.0M0.04s)enialnedwdaes-
anrueditbhreanncuhmsbuesresdo(fmuacnuesm-oconaetsedusperdob(ecso)ntpreorltepsrto.bes) orthe numbers of c2r3e.a1s2e,dPwh<en0.0U0.01f)e.linWaithwians1p0rdoabyesda(ftAerNOthVeAp,reyFs3w1i9tch=,
touchingM. seniletentacleswithmucus-coatedprobeselic-
i(lAarNaOmVoAn,gFihnd4iSvi=dua0l.7n6u,diPbra=nch0.s61r)e.gardless oftheir size pitreodbetshediddis(cShcahregfefe'osft7es5t,%Pfe=we0r.0n0e6m7a)to(cFyisg.ts5).thBayntchoenternodl
Whengelatinprobescoatedwithmucusfromindividuals oftheexperiment,touching U.felinatentacleswithmucus-
ofA. papillosa that had been feeding upon U.felina were coated probes again resulted in a small but nonsignificant
tested on the tentacles of U.felina, nematocyst discharge
Wwhaist6n7ey%lUesstetsth,ant/d4i]s6ch=arg2e4,intPot=he0co.n0t1r)ol(pFirgo.be4s).(MWahnenn-
probescoated with mucus fromA.papillosa that had been 1.75-
feeding on U.felina were used to probe the sea anemones
M. senile and Aulactinia stella, nematocyst discharge was 1.5- (7)
1.25-
I
1
60- Controlprobes (4) '-O4-H 0.75-
Mucus-coatedprobes
0.5-
I 0.25-
Q
Oi 10 15
'-4O
Days
I
Figure 5. The effect ofAeolidia papillosa mucus on the relative
M.senile A.stella U.felina number ofdischarged nematocysts following prey switch from the sea
anemone Urticinafelina to the sea anemone Metridium senile (SD).
Figure4. Numberofnematocystsdischargedintocontrolprobesor Mucus-coatedprobeswereusedtoprobetentaclesoftheseaanemonesU.
intoprobescoatedwithmucusfromindividualsofAealiJiapapillosathat felina and M. senile (in 10 7 A/ N-acetylneuraminic acid), and were
had been feedingon Urticinafelina (SD). Mucus-coated probes were compared against controls foreach species fora period of2 weeks. A
sutseellda,toapnrdobeU.tefnetlaicnlaes(ionft1hCe)"s7eaManNe-maocneetsylMneeturriadmiinuimcseanciilde,)Aaunldactwienrieu rienltaoticvoentvraolluperoofbe1s.0ocnorDraeysponfdosretaocthhesenaumabneermoonfenespmeactioecsy.sDtastdaisocbhtaarigneedd
comparedagainstcontrol probesofgelatinonly.The numbersinparen- frommucus-coatedprobesforeachdaywerenormalizedagainstcontrols
thesesarethenumbersofanemonesused(controlprobes)orthenumbers torthatdayandforeachspeciesofseaanemone.Thenumbersinparen-
otnudibranchsused(mucus-coatedprobes)pertest. thesesarethenumbersofnudibranchsusedpertest.
118 P. G. GREENWOOD ETAL
Does the nudihrancliproduce itsown inhibitorymucusor
1.25 (4) -O A.elegantissima simplvbecome coveredin theprey's mucus'.'
1- O-- M.sem/f Mucus was wipedawayfromthedorsal surface ofeight
individualsofA.papiltosathathadbeenfeedingonthesea
anemone M. senile. Forty-five min later, gelatin probes
0.75- coatedwith new mucusfromthose samenudibranchswere
1
used toprobe tentaclesofM. senile. Nematocystdischarge
0.5- into those probes was no different from nematocyst dis-
charge intoprobescoated with mucus from the sameeight
0.25- (3) (inSdcihveifdfuea'lssteosft,A.Pp=api0l.l6o0sa) b(eFifgo.re7)w.iNpeimngattohceysmtucduisschaawragye
into both groups of mucus-coated probes was well under
Days 1i0 15 h(aAlWfNhOetVhnAe,prnFoub2me.bslhecro=att1eha0dt.5w4id,tihsPcMh.a=rsge0end.i0le0i1nm)tuoc(Fuicsgo.nwt7re)or.le upsreodbetso
probe tentacles ofother individuals ofM. senile, nemato-
anunFmeibmgeournreeofM6e.dtirsicTdhhiaeurmgeefdsfeenncitelmeaotofonclAyyesolttoisdhifoaorlhpluoMpw.iilnlgsoesnpairleemyuacsnwudisttchhoenfsretaohemanrteehlemaotsineveea ctyhsatnsidntioscchoanrtgreodl pirntoobetshe(Sptruodbenets'sint nteustm.bef6rs=no1.d1i4t.tePren=t
Atanctlheosploefutrhaeesleeaganatniesmsiomnae.sMMu.cusse-nciolaeteadndprAo.beeslewgearnteisussiemdato(ipnro1b0e~7teMn- 0.30) (Fig. 8).
N-acetylneuraminic acid), and were compared againstcontrols foreach Discussion
speciesafter2weeks.Arelativevalueof1.0correspondstothenumberof
nematocystsdischargedintocontrolprobesonDay foreachseaanemone Thepresentstudyshows,forthefirsttime,thatthemucus
species. Data obtained from mucus-coated probes for each day were from a nudibranch specifically inhibits the discharge of
anpenorremmtaoeslntie.z.edThaeganiunmsbtercsonitnroplasrefnotrhestheastardeaytheanndumbfoerrseoafchnudspiebcriaenschosfusseeda nneemmaattooccyyssttsdfirscohmarsgeeaaisnelimmointeedtteonttahcelesa.neThmiosneinhsipbeictiieosnoonf
which the nudibranch has been feeding. Moreover, the
nudibranch mucus changes to inhibit the nematocyst dis-
increase in nematocyst discharge over that into control chargeofadifferentseaanemonespeciesifthenudibranch
probes (Scheffe's test, P = 0.072) (Fig. 5).
411-i
//'a secondpreyspecies isoffered, willthe effectofthe
inidihriinch mucus on nemtitocvstdischarge change?
FourindividualsofA.pcipillosuwerefedM. senileforat <u
least 21 days, and tentacles of both M. senile and Antho-
pleuraelegantissimaweretestedwithmucus-coatedprobes.
M.senilenematocystdischargewas56%lowerintomucus=- Q
coatedprobesthanintocontrolprobes(Student's;test,/ O
9.6, P < 0.0001); Aiithopleuni ele^nnti.ssinui nemato-
cyst discharge into mucus-coated probes was not different
from discharge into control probes (Student's / test. r(, =
0.545. P = 0.61) (Fig.6). NematocystsfromAnthopleum
elegcintissimu were all basitrichous isorhizas. The nudi-
branchs were then offered both M. senile andAnthopleum
eleg(iHti<i<iii>ui. After the nudihranchs had been feeding on
both prey species for 14 days, testing with mucus-coated
probesshowednematocystdischarges34% lowerthancon-
trol probes forM. senile (Student's / test. t4 = 2.78, P =
0.05) and 64% lower than control probes forAnthopleum
ek'xuntisaimti (Student's ; lest, t4 = 17.06, P < 0.0001 )
(Fig. 6).
SEA SLUG MUCUS INHIBITS NEMATOCYSTS 119
<.C
Nematocysts ijO
Discharged O
of
Number -
120 P. G. GREENWOOD ETAL.
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