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Biometric Analysis of Nautilus pompilius from the Philippines and the Fiji Islands

Authors:
From:NAUrLUS
EditedbyヽBruceSallndersandNeilH.Land■nt
(Plellumhbb価 c∝pOntiOn,1987)
Chapter7
BiometricAnalysisofNα utilus
pompiliusfromthePhilippinesandthe
Fililslal■ ds
KAZUSHIGETANABEandJUNZOTSUKAHARA
llntroduction
2 4aterialsandMethods
21Fieldヽ lethods
22LaboratowMe■ OdS
3Results
31AverageRelativeCrowth
320ntogeneticChangeofShellForm
33NepionicShells
340onadDevelopmentandSexualDimorphism
4Conclusions
105
106
106
106
108
108
110
110
111
112
1.Introduction
SinceMoseley(1838)firstanalyzedthegeometryoftheNα utilusshell,itslnor―
phO10gicalfeaturesandallometricgrowthhavebeenstudiedbymanyauthors
(ThOmpson,1917:HuXley,1932,Hirano,1977:HiranoandObata,1979;Hirano
etal.,1980)MostpreviousM′ ork、vasbasedonsmallcollectionsofindividual
specimens,thesexesanddetailedlocalityrecordof、vhichM′ ereunknoM′ nln
1981and1983,aresearchprOjectontheecologyofNpompiliuswascarriedout
inthePhilippinesandtheFililslandsasajointventureofJapanese,Philippine,
andFijianscientists(undertheleadershipofProfSHayasakaofKagoshima
University)Duringthisproject,weexaminedthebiometricpropertiesofsoftand
hardtissuesincapturedanimals(Hayasakaet α
l,1982;Tanabeet αl,1983,1985,
Tsukahara,1985)ThisChaptersummarizesourworkonNpompilius,withspe‐
cialreferencetosexualdimorphismexpressedinallometricrelationshipsand
thevariationintheshellandsoftpartsinthetM′ opopulationsfromル videlysep‐
aratedareas
KAZUSIⅡ GETANABE
Ceologicallnstitute,FacultyofScience,UniversityofTokyo,Tokyol13,
JapanJUNZOTSUKAHARA
DepammentOfBiology,FacultyofScience,KagoshimaUniver‐
sity,Kagoshima890,Japan
106
2.Materillζ IaMetlodし ,
ChapteF7
ThischapterisbasedmainlyonthreecollectionsofNpompiliusfromthe
PhilippinesandtheFijilslandsOnecollectionconsistsof52specimensthat
werecapturedintheTa■ onStait(depthOf120‑3101n)abOut2‑3knlo∬ Bindoy
Village,NegrosOriental,thePhilippines,in1981byHayasakaandothers(forthe
actualcatchrecords,seeFig3andTable10inHayasakaet α
l,1982)Theother
Lピ│=l路
1:生
Iぶ
r版lf∬IF:1黒11:
ml腑│卜
11辞
WT蹴i響:思L器
details,seeTanabeet αl.,1985)ヽ eaSurementsbyTanabeet α
I(1983)onthe
shellsof31specimensofNα utilusfrOmtheSuvaarea(collectedbyHayasakaand
Shinomiyain1981fromalmostthesamelocationsasthoseofthe101specimens
mentionedabove)M′ erealsousedinthisstudyThePhilippinesandtheFiji
lslandsrepresentthenorthMresternandsoutheasternmarginalareasoftherange
ofNpοmpilius(SeeFiglinChapter3),therefOre,thespecimensfromthesetwo
sitesareespeciallysuitableforanalysisofgeographicVariation
2.1.FieldMethods
Allthespecimensstudied、 verecapturedusingbaitedtrapS,M′ hichwere
spedttydedgnedbriemskbyPhh:IILTl認
}識:l鑓1鶴
eachanimal、 vaslabeled,、 veighed,Ine
3T,t離
e轟Wfκ
lIIttl堪
releasedintheirhabitatafterlaboratoryobservationM√ asdeterminedbythepres―
]IL恥:鶴
li賜
saundersandSpinosa,1978)ヽ lⅨimumshelldiameterandaperturalwhorl
breadthandheightweremeasuredoneveryspecimenwithaslidecaliper〔 ac
curacy=005mm)ExceptforonespecimenflomthePacificHalborarea,alll市 e
animalswereweighedusingadialscale(aCCuracy± lg〕 Thesemeasurements
wereusedtoanalyzeaveragerelativegrOン ,thandsexualdimorphismlnaddition
tothesebasiccharacters,freshgonadsfron■ somespecimenscOllectedinboththe
PhilippinesandtheFililslandsM′ ere、veighedtodeterminetherelationshipbe―
t、veensexuallnaturityandshellsize
2.2.LaboratoryMethodS
4easurementsfromallthespecimenscapturedwereanalyzedtoinvestigate
theallometricrelationshipsamongcharactersineachsampleandthevariation
intotal、veightandshellsizeRelativegro、 vthandontogeneticchangesinshell
formwereexaminedintheshellsdf28animalsfromthePhilippinesandtheF"i
lslandsTheseshellswerecutandpohshedalongthemedianplane,andthe
BiolnetricAnalysisofNα u[iluspompi]ius 107
FigurelBasicmorphology,orientation,andmeasurementsof■ eshellofNpompiliusinmedian
(1け
anddorsalvental(■ gllt)sectiOnsseetlletextfordiscussionReprintedwlthpermissionf■ om
Tanabeetai(1985)
nepionicshellsize、 ν
aslneasuredEach half''shell、 vasalsocutalongthelon―
gitudinalaxisofthececumonthemediansectiontoproduceadorsal― ventral
section(Figl)Shelldiameter(D),half‐ lengthOfthe、vhOrlbreadth(B/2),、 vhOrl
height(H),diStancefromcoilingaxistoumbilicalshoulder(C),andinnerwhorl
height(F)weremeasuredonthehalveddorsal― ventralsectionsatintervalsof
180° leasurementsofmediananddorsal― ventralsections、veremadev′ itha
profileprOjector(NikonV‑12),attaChedtoadigitalmicrometer〔 accuracy± lμ
m)
Onthebasisofthesemeasurements,theshell― fOrmratiosproposedbyRaup(1966)
andChamberlain〔 1976),suchas、 vhOrlexpansionrate[(R′ Th1〕 2,n:V′ horinum‐
ber,sincen>2πl,diStanceoftheM′ hOrlstothecoilingaxis〔 C/R),relatiVewhorl
thickness(BH),andflankposition(F′ 1)),ヽVerecalculatedforeachspecimenat
severalgro、 vthstages.ThefolloM′ ingabbreviationswereusedinthebiometric
descriptions:
=Samplesize
=Arithmeticmean
=Coefficientofvariation
=Standarddeviation
=Observedrange
nepiOnic
constriction
108 Chapter7
Ox
α
=Standarderrorofthesamplemean
=Slopeofallometry(grOWthratio)
=StandarderrorofthegroM√ thratio
=Correlationcoefficient
=Probabilitylevel
202122
LOG(SHELLOInHETER〕
202122
LOG(SHELLDInHETER〕
3.Results
3.1.AverageRela●veGrowth
Weappliedbivariateanalysis(Imbrie,1956)tothiSSpeciestoexpressthe
allometricrelationshipbetlt7eenapairoflnorphologicalcharactersTherelation‐
shipbet、 veen、νhorlbreadth〔 B)andShelldiameter(D)andbetWeenwhorlheight
(H)andShelldiameter(D)forfemaleandmalespecimenstromtheSuvaareais
representedondoublelogarithmicplots(Fig2)Thes10pes(growthratios)ofthe
reducedm● oraxesofBvsDinmalesandfemalesbothindicateslightlynegative
a1lomet理
,、vhilethoseofHvsDindicateisometryAccordingtoKermackand
Haldane(1950),thedifferenceintheslopesofthetworeducedmajoraxesis
evaluatedbycalculatingthestatisticz:
Z=(α .― α
2)/V′ σ
1+σ
2
vhere α
landα
2(α
2)arethes10pesoftheaxesand σ
α
,andσ
α
2arethe
standarderrorsofthetwoslopesUsingthismethod,v′ ecalculatedzvalues
betweenthetworeducedmaloraxesofthemaleandfemalesamplesfromthe
SuvaareaThezvaluesbetweenfemalesandmalesintheSuvasample〔 027for
logBvslogD:056forlogHvslogD)aremuChSmallerthanthecriticalvalue
196atP=005:hence,theslopesinbothsexesfromthesameareadonotshow
21
¨󰿯󰿯
Figure20oublelogarithmicscatterplotsWithreducedmaioraXesshowingthea1lometricrelationship
bet、veen、 vhorlbreadthandshelldianleter(lel)andbetween、 νhorlheightandshelldiameter(right)
inmaleandfemalespecimensofNpompi]iusfromtheSuvaareaoftheFttilslands
0,74 0111 ■ 0946呟
O079
Phippines(Taヽ onAreaN・ 52)
Lo9B‐ 1つ 4LogD― o398
Fil(SuvaAreaN・ 101)
LogB・ 0785Lo90+0167
■ 088%手 0037
2122
LOG(SHELLOinHEIER〕
BiometricAnalysisofNα utiluspOmpilius
Figure4Doublelogarithmicscatterplots
withreducedmaloraxesshowingtheal
lometricrelationshipbetweentissue
weightandshelldiameterinthesamples
(maleSandfemaleJOfNpompiliusfrom
theFijilslandsandthePhilippines
‐ 0805,%‐ 0398
109
ω
󰿯Fl,(SuVaAreaN‐ 01)
Lo9H・ 1022Lo9D― o231
・ o969,τ
0025
17:、 20212223
LOC(SHELL010HETER)
Fittre3.Double10garlhllicscatteFp10tswithreducedmaloraxesshowingthea1lometicrelationship
betweenwhorlbreadthandshelldiameter(left)andbe■ Veenwhorlheightandshelldiameter(right〕
inthesamples(malesandfemales〕 ofNpompiliusfromtheFijilslandsandthePhilippines
anystatisticallysignificantdilferenceSimilarly,malesandfemalesfromtheSuva
areashownosignificantdifferenceintheslopesoftheirreducednlaloraxes
bet、 veenpairsoflogB,logH,and10gDTherefore,thelineartrendsofthereduced
maloraxesbetweenpairsofmorphologicalcharactersinthesamplesfromthe
SuvaandPacificHarborareasofFijiareessentiallyequivalent.
Ontheotherhand,cOmparisonsbetv′ eentheFijianandPhilippinecollec‐
tionsrevealwidedifferences(Figs3and4).Asignificantdifferenceoccursin
thes10pesofthereducedma,oraxesbetweenthetwOsamplesforwhorlbreadth
,PHI[IPPINES(TANONAR[AN・ 34)‐
‐ 0863 0297.
202122
L00(SHELLDInMElER,
Phlppines(TanonAreaN・ 33)
201、
1■ 0Chapter7
EVEOAMFTERH000LENCTH
0。
0
8。
αШΣ
TANoNSAMPLE
FI」 ISAMPLE
MALE
oFEMALE
MALE
FEMALE
Figure5Dollblescatterplotssho、 villgthea110metricrelatiollshipbetweeneyediameterand
lel■ghinthespecimensofNpompiliusfromtheTa● On,PhilippinesandSuva,Fttiareas
andwhorlheightvsshelldiameter(Z=3.46forlogBvs10gD;z=1623for
logHvs10gD;z>2.58=Zp‑0。 .,wherePく 001iSsignificant)Inaddition,
differencesoccurintherelativegowthpatternofeyediametervshoodlength
(Fig5)
3.2.OntogeneticChangeofShellForm
Ontogeneticchangesinshell‐ formparameters、 vereexalninedin21speci―
mens〔15malesand6females)frOmtheSuvaarea(Fig6)FlankpOsitionand
thedistanceofthe、 νhOrlstothecOilingaxisremainnearlyconstant,whereas
relativev′ hOrlthicknessand、 vhorlexpansionratedecrease、 vithgrOwth.Inthe
earlystagesofdevelopment,malesandfemalesshO、 vnosignificantdilferencein
theseshell― formparameters,butinthematureOralmostmaturestages(55■ ),
maleshavelargervaluesofrelativeM′ hOrlthicknessandMrhOrlexpansionrate
thandofemalesTheselargervaluesindicatethatmaturemalesusuallyhave
larger、vhorlradiiandwhorlbreadthsthallmaturefemales
3.3.NepionicShells
Themeannepionicshellsizeandits95%collfidenceintervalin3Fijian
specimens(2750± 204mm,s=244mm,V=886,andOR=244‑326
mm)areshghtlylargerthanthosein6specimensfromthePhilippines(25.72±
111
Figure6Twoseriesofdoublescaterplotsoftheshell‐ formparametersofRaup{1966)inselected
specimensofNpornpiliusfromtheSuvaacaofFttishOWingtheontogeneticchangesinshellform
betweenmalesandfemalesReprintedwithpenllisslonfromTanabeeta:(1985〕
104mm:s=o99mm,V=3.84,OR=247‑271mm)AStudent'st― test,
however,doesnotshowastatisticallysignificantdifference(P<005)inthe
meannepionicshellsizebet、 veenthet,vosamplesFromtheoxygenisotopic
compositionofNα utilusshells,Cochranetal(1981)andBE.Taylorandや Vard
(1983)concludedthatthenepionicconstrictionformsathatchinglfthisOpinion
iscorrect,theforegoingdataprobablyreflectthesimilarityinthesizeofthe
postembryonicyoung.
3.4.GonadDevelopmentandSexualDimorphism
Thehypothesisthatvariationintotallive、veightandshellsizeinmature
specimenscanbeattributedtosexualdimorphismhasalreadybeencOnfirmed
forNpompi]iusiOmthePhilippinesandtheFijilslands(Haven,1977a;や Vard
etal,1977:ヤVardandMartin,1980;Hayasakaet αl,1982;Tanabeet α
l,1983),
forNmα cromphα lusfromNewCaledonia〔 WardandMartin,1980),andfOrN
belα uensisfromPalau,VVestCarolinelslands(SaundersandSpinosa,1978)In
thesespecies,Inaturemalesgenerallyhavelargershellsandheaviersoftparts
π
Ш α
× Ш ´ Ш Ш
RELATIVEWHORLTHiCKNCSS FLANKPOSITiON
112
8
:器1ミ
]脚 PttNES
elヽ
Л


lfi
.

1lo120,3o,40150160
SHELLDIAMETER(mm)
Chapter7
Figure7Doublescatterp10tsof
80nadindexltestisorovary
WeiよνSOfttissuewe18ht(%】 vs
shelldiameterintheselectedspec―
imellsofNpOmpiliusfTomthe
PhilippinesandtheFijilslands
Ш
170130
thanmaturefemaleslnaddition,Stenzel〔 1964),Haven(1977a),Saundersand
Spinosa(1978),andArnold(1984)havepOintedoutthattheshellsofinature
maleshaveabrOaderandrOunderaperturethanthoseoffemalesofsimilarage
ThesedifferencesaresupportedbythespecimenscollectedfromtheFijilslands
(Fig6),althOughprincipalcomponentanalysisOfmaturespecimensfromthe
Philippinesrevealednostatisticallysignificantdifferencesinthebasicshell‐ form
ratiosbetv′ eensexes(Tanabeet αl,1983)
Indescribingshelllnaturity,theearlierliteraturehasreliedmainlyonchar―
acteristicshellfeaturessuchasablackenedandconstrictedaperture,fllsingto‐
getherofthefinalt、vOOrthreesepta,andathickenedlastseptumlnthisstudy,
weexaminedtherelativegonadweightinselectedspecimensfromtheF"ilslands
andthePhilippinesScatterplotsofthegOnadindexloVaryortestisweightsOlt
tissueweight(%)]VSShelldiameterareshownfortwosamplesinFig71nthe
femalesllomtheFijilslands,Ovaryweightincreasesabruptlyafterashelldiameter
of120mmandattainsamaximum(〜 15g)ataShelldiameterOfapproximately
140mlnlncontrast,gonaddevelopmentislnoremarkedinmales,andfullde―
velopmentOftestesdoesnotOccuruntilashelldiameterof140‑150mlnlf、 ve
considersexuallnaturityas30onthegonadindex,maleshavelargershellsthan
femalesatthispointThelargegonadindicescalculatedforthePhilippinespec‐
imensindicatethatmostofthem(especiallythefemales)haVeapproachedor
attainedsexualmaturity(Tsukahara,1985)TheaVerageshelldiameteratmaturity
forbOthsexesinthePhilippinesampleisabOut25mmlargerthanintheFijian
sampleleg"17164mmand14721mmformalesfromthePhilippines(N=15)
andFijilslands(rヾ =14),respectively,seealsoFig7,andFig12inChapterlll
llVardetαl(1977)andHayasakaetal(1982)havealSOnotedthatmatureoralmost
maturespecimensofNpompiliusfromthePhilippinesaremuchheavierand
largerthanthosefrOmtheFililslands
4.ConclusiOns
lntheFijilslandsandthePhilippines,rヾ pompiliusexhibitsadistinctsexual
dimorphisminweight,shelldimensions,andsofttissuesMaturemalesgenerally
BiometricAnalysisofNautil.lspompi]ius 13
possessabroaderM7horlaperturethanlnaturefemalesThetwOsamplesfromthe
PhilippinesandtheFililslandsareclearlydifferentinoverall、 veight,sizeat
maturity,andtheslopesofthea1lometricrelationshipsofseverallnorphological
charactersThelnorphologicaldifferencesbetM/eenthesamplesfromthet、 voareas
aremuchgreaterthanthosebet、 veensexes、 vithinthesamearealnaddition,
4asudaandShinOmiya〔 1983)discOVeredastatisticallysignificantdifferencein
allelefrequenciesbetM′ eensamplesfromthesetwoareasFromtheselinesof
evidence,weconcludethatpopulationsofNpompiliusfromtheFililslandsand
thePhilippinesaredifferentiatedbothgeneticallyandmorphologically
AcKNOWLEDG卜4ENTSWeareparticularlyindebtedtoProfShozoHayasakaOfKa―
goshimaUniversityfortheuseofhisfacilitiesandfOrhisencouragementboth
inthefieldandinthelaboratoryOurthankstoDrAlfredoEEvangelista,As‐
sistantDirectorofthePhilippinesNationalMuseun■ ,ProfAngelCAlcala,Vice
PresidentofSilhmanUniversityinthePhilippines,andDrUdayRaj,Director
ofthelnstituteofヽlarineResources〔 IMR)attheUniversityoftheSouthPacific
(Fijl),fOrtheirassistanceandtheuseoftheirfacilitiesforplanningandoperating
ourfieldstudiesThanksalsototheothermembersoftheprojectinthePhilip‐
pinesandFilifortheirassistanceinthefieldandfortheirhelpfuldiscussions
eexpressoursinceregratitudetOthestaffoftheIヽ 4Randヽlr
7ilsonValloces
inBindoy,Philippines,M′ hohelpedustrapNautilusDrNeilHLandmanofthe
AmericanMuseumofNaturalHistOryandDrAndrewSwanoftheUniversiけ
CollegeofSv√anseacriticallyreadthemanuscriptThiswork、 vassupportedby
Grantsin‐ AidforOverseasScientificResearch(No57043059for1982;No
58041055for1983,No59043050for1984)
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Of
utti■u旦
Qュ pLュ
uttSowerby(NewCaredonia)andNautilus
po■ 211lЦ ttL.(Fijl).2ュl二 Qg02Eェ22■aeO。 1llnat01.221ュ QoQQg■ ,
41,1‑16.
THOMPSoN,D.1917:Qュ QェQEttL
E。
.1116p.canbridgeuniv.
Press,London.
TSUKAHARA,
.1985:HistO10gicalandhistOchenicalstudiesOf
gonadsof
Ч
2旦 
Qュ plll■frOmFij■ .
:S.Hayasaka(ed.):
MarineecOlogicalstudiesthehabitatOfN奎 Lll彗29■2111聖in
theenvironsOfvitiLebu,Fijl.
g。Lユ
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o皇=
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12ュ.,(4):50‑60.
WARD,P.D.andMARTIN,A.W.1980:DepthdistributionOf
iluttp。
p■

nFijiald u■
Q=。
pLュ1坐 ,
nNew
CaredOnia.y,1■ gttr,22,259‑264.
,STONE,R.,wESTERMANN,C.andMARTIN,A1977:NotesOn
aninalweight,caneralfluids,swilnmingspeed,andc。 10r
polymOrpllislnofthecepha10pOd
uニ
aQ二Qュ ph全
22192L19■2gy,3,377‑388.
... Although specimen NMP-491B is only partly preserved, the shell bears some diagnostic features that characterize modern Nautilus pompilius. These characteristics are as follows (Table 1): (1) The shell W/D ratio of 0.50 closely approximates those of the modern N. pompilius in the Philippines and N. macromphalus Sowerby, 1849 (0.48-0.52 and 0.52, respectively;Hirano and Obata, 1979;Tanabe and Tsukahara, 1987), but the ratio is smaller than those of the Eocene-age N. praepompilius Shimansky, 1957 (0.60;Saunders et al., 1996) and N. aff. cookanum Whitfield, 1892 (0.67;Squires, 1988). ...
... Abbreviations: V, ventral saddle; L, lateral lobe; USh, saddle in umbilical shoulder; USe, saddle near umbilical seam; D, dorsal lobe. Tanabe and Tsukahara (1987), Saunders (1987), Ward (1987) N. macromphalus modern 0.52 15-16% Saunders (1987), Ward (1987) N. praepompilius late Eoceneearly Oligocene 0.60 9% Saunders et al. (1996) N. aff. cookanum late Eocene 0.67 6% Squires (1988) time. ...
Article
Full-text available
A chambered nautilus shell from the early Pleistocene deep-water sediments in the Bolinao area of Pangasinan province, northwestern Luzon, Philippines is described. Although the shell is fragmentary, the shell features indicate that the specimen is referable with reservation to the extant Nautilus pompilius Linnaeus, 1758. This finding represents the first and oldest fossil record of N. pompilius and complements the Plio-Pleistocene gap of the nautiloid fossil records. Taphonomic implications for Cenozoic nautiloids were briefly discussed.
Article
Morphometric analyses of shell morphology in the Cretaceous nautiloid Eutrephoceras clementinum (d'Orbigny, 1840) (Cephalopoda, Mollusca) from the Ariyalur area, southern India, reveal ontogenetic change from hatching to maturity as well as intra-specific variation in shell morphology. The shell breadth has a negative allometric relationship with shell diameter and with whorl height, and the umbilicus diameter has a positive allometric relationship with shell diameter. This shows that shell shape became relatively thinner with less variation, and the umbilicus diameter became relatively broader with growth. The siphuncle position moves from a dorso-central to ventro-central position with, growth. A constriction was recognized on the early whorl at 20 rum in shell diameter, and the interval angles of succeeding septa were changed at the 8th septum, indicating that they hatched at this stage. The bending of umbilical walls of apertures toward the center of coiling Suggests that E. clementinum attained maturity at about 115 mm in shell diameter. The comparison of the shell morphology of E. clementinum with that of E. bouchardianum (d'Orbigny, 1840) reported in the literature clarifies their difference in whorl shape and umbilical size, especially in the adult stage. This kind of morphometric study of nautiloids is essential for elucidating their adaptive designs for environment and mode of life, functional shell morphology, taxonomy, phylogeny, and evolution.
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