Sexual Dimorphism in Flathead Grey Mullet Mugil Cephalus (Linnaeus)

2007·1.8 MB·

by  Jency Paul

MISCELLANEOUS NOTES
Pathni (1978),RitakumariandNair(1979)and Badolaetal. The detailed morphometric and meristic characters of
(1982). Our observations on sexual dimorphism in Puntius bothmaleaswellasfemalefishwerestudied(Table 1),butno
conchonius(Ham.-Buch.)isbasedon the study offiftymale striking differencewasseen.Thedifferencesare(i)malewith
andfemalespecimenseach,collectedbetweenNovember2003 darkblackshadeon thedorsal, ventral andanalfins, absentin
and January 2004. The fishes were segregated on the female(Fig. 1),(ii)Upperportionofthebodyshiningolivegreen
mentioned sexual dimorphic characters, and dissected for and lower portion silvery in both sexes; but there is pinkish
confirmation.Wegothundredpercentconfirmationandthen colourinmalesbetweenthesetwoportions,whichisnotvisible
decidedtoreportitforanadditiontothescientificknowledge inthefemalespecimens,and(iii)thesnoutisbroaderonupper
based on the study ofmorphometric characters. sideinthefemalecomparedtothemale(Fig.2).
Badola, S.P., H.R. Singh & A.K. Dobriyal (1982): Note on sexual 198-210.
dimorphism in Barilius bendelisis (Ham.). Indian J. Anim. Sci. Singh, H.R., S.P. Badola & A.K. Dobriyal (1987): Geographical
52(12): 1284-1286. distributional list of ichthyofauna of the Garhwal Himalaya
Day, F. (1878): The Fishes of India: Being a Natural History ofthe with some new records. J. Bombay Nat. Hist. Soc. (84):
FishesknowntoinhabittheseasandfreshwatersofIndia, Burma 126-132.
andCeylon. William Dawson andSons Ltd. Pp. 778. Swarup,K.&A.Swarup(1975):SexualdimorphisminPseudeutropius
Pathni,S.S.(1978):Anoteonsecondarysexualcharactersin Kumaun atherenoides (Bloch). Curr. Sci. 44 (16): 588.
Mahseer Tor tor (Hamilton) and Torputitora (Ham.) in Uttar Talwar, PK. & A.G. Jhingran (1991): Inland fishes of India and
Pradesh. Indian J. Anim. Sci. 48 (10): 773-775. adjacentcountries.Oxford&IBHPubl.Co.Pvt.Ltd.,NewDelhi.
Ritakumari, S.D. & B.K. Nair (1979): Sexual dimorphism in the Pp. 250-295.
Loaches Noemacheilus triangularis (Day) and Lepidocephahts Tilak,R.(1975):FurtherstudiesonthedimorphisminLepidocephahts
thermalis (Cuv. & Val.). J. Anim. Morph. Physiol. 26(1-2): guntea (Hamilton). Newsl. Zool. Sttrv. India 1(4): 74-76.
21. SEXUAL DIMORPHISM IN FLATHEAD GREY MULLET MUGIL CEPHALUS (LINNAEUS)1
JencyPaul2-4, Honey Sebastian3, N.D. Inasu2-5andC.O. Joshi2-6
'Accepted May 2006
-Fisheries Research Laboratory, Post Graduate and Research Department of Zoology, Christ College, Irinjalakuda, 680 125,
Kerala, India.
Tost Graduate and Research Department of Zoology, Sacred Heart College, Thevara, Kochi, 682 013, Kerala, India.
Email: [email protected]
4Email: [email protected]
'’Email: [email protected]
‘’Email: [email protected]
Introduction culture of fishes, hybridization experiments, hormonal sex
Sexualdimorphismiswidespreadinnatureandcanbe control, identification of maturity stage, identification of
influenced by sex specific natural selection resulting from hybrids, breeding season, induced breeding, seedling
ecologicaldifferencesbetweenthesexes(ReimchenandNosil production technology and also in the observation of
2004). Differencesinthe selective pressuresexperiencedby courtship and mating, mate selection, andpreference.
the sexes can ultimately result in the evolution of sexual The study on sexual dimorphism has been carriedout
dimorphismofmorphologicaltraits(Andersson 1994).Many in avery few species offishes like Tetraodon travancoricus
fishspeciesshowsexualdimorphism,aconditionwheremales (Inasu 1993),Puntiusfilamentosus(Thobias 1974),Priacanthus
and females are different in colour and/or form, thus sexes hamrur(Tessy and Inasu 1998), and Ompokbimaculatus and
canbedetectedexternally. Horabagrusbrachysoma(KurianandInasu 1997).
Comparison of morphological features in males and Thepresentworkdealswiththesexualdimorphismof
femalesofsimilarlengthgroupfacilitatetoworkoutthesexual the Flathead Grey Mullet M. cephalus belonging to Order
dimorphism. Species that show difference in coloration Mugiliformes and Family Mugilidae. It is commonly called
betweensexesaresaidtodisplaysexualdichromism(Martin ‘Kanambu’, ‘Alameen’or‘Thirutha’ inMalayalam,‘Madavai’
Moe2002). inTamil, and ‘Kathiparega’ inTelugu (Talwar and Jhingran
Thestudyonsexualdimorphismisofgreatsignificance 1991).GreyMulletsaremostlymarine,distributedintemperate
in taxonomy, bionomics, reproductive biology, monosex andtropical seas,estuariesandsomerivers,butspawninthe
226 J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007
MISCELLANEOUS NOTES
Table1:Average bodyweightineach lengthgroupof Discussion
maleandfemaleMugilcephalus(Linn.) In M. cephalus, mature male acquires a pinkish red
Lengthgroup Totalnumberof Averageweight(gms) hue on the body particularly on the basal portion of 1st and
Fishexamined 2nd dorsal fins, ventral fins and anal fin during the approach
ofthebreeding season, butinfemalessuchcolorationis not
(mm) Male Female Male Female
noticed. The fine colour difference between the two sex
160-169 27 31 45.71 49.40 groups tend to fade once the breeding period is over. This
170-179 38 33 64.06 66.70 pattern oftemporary sexual dichromism is alsoobserved in
180-189 44 25 79.21 82.94
Tetraodon travancoricus (Joshi 2004), Horabagrus
190-199 30 41 82.5 87.00
200-209 - 24 - 100.20 brachysoma (Inasu 2004), Anabas testudineus (Roychan
210-219 - 27 - 108.70 2005),andBendelisischedra(PathaniandGaur 1989). Ithas
a passive or active role in reproductive behaviour as the
bright body colour attracts the opposite sex and helps in
sea. This non-predatory fish feeds on zooplankton, completingthespawningact(MartinMoe2002andRoychan
phytoplankton and detritus in the bottom mud. 2005).Variation in colourcan also be due toenvironmental,
M. cephalusisoneofthecommonspeciesofmulletsin nutritional and ecological factors, such as competition, and
theIndianregionwhichisabundantincatchesfromtheChilka predation. Theendocrineglandsalsoplay an importantrole
lake(Orissa),MahanadiandGodavariestuaries, Pulicatlake inbreedingcoloration.
(Tamil Nadu) and in the backwater lakes ofAstamudi and Femalesare heavierthanthemalesofthe samelength
Vembanadu (Kerala). They withstand wide fluctuations in group. Forfacilitatingabettercomparisontheaveragebody
salinityandsuitableforbrackishwaterpolyculturealongwith weight in each length group ofmale and female is given in
shrimps,ChanosandpredatoryfishlikeLates(Thampy2002). Table 1.The largebodysizeoffemalefishcan beexplained
Sea ranching ofM. cephalus has been done successfully in as the fecundity ofthe fish. Andersson (1994) reported that
Hawaii(Grimes 1998)andalongtheGujaratcoast(Anon.2000). females tend to have larger gonads than males with large
M. cephalus is reported as a potential fish for induced energy rich eggs, whereas males have much smallergonads
maturationandbreedingtechnologieswithgreatsuccess(Rao thatproduce numerousrelatively inexpensive sperm.
2000). So the study on sexual dimorphism is of great This study has focused on the ultimate explanations
significanceinthisfishasitisapreliminarysteptodistinguish ofthe observed sexual dimorphism inM. cephalus (Linn.),
malesandfemales. yet it wouldbe interesting tofurtherexamine the proximate
causes of these differences.
Method
ACKNOWLEDGEMENTS
About 320 specimens (males 139 and females 181 of
)
adult M. cephalus were collected in fresh condition from
February to July 2005 from the estuarine region of We are grateful to Rev. Fr. Jose Chunkan (CMI),
Kanakankadavu(Emakulumdistrict,Kerala).Theyweresorted Principal,ChristCollege,Irinjalakuda,forprovidingallfacilities
intovariouslengthgroups.Thefinemorphologicaldifferences for the study. The co-author is also grateful to University
between males and females ofthe same length group were GrantsCommissionforprovidingJuniorResearchFellowship
studied and compared, and total weight of each fish was during the tenure of which the present work was carried
recorded separately. out.
REFERENCES
Andersson, M. (1994): Sexualselection. Pub.by PrincetonUniversity (Gunther).Pp.25-29.In:Sexualdimorphismofsomeindigenous
M
Press. Braabury,J. andAndersson, (eds) 599pp. ornamentalfishes,Vol.I.MarineProductsExportDevelopment
Anon. (2000): Biodiversity Conservation in West Bengal. Fishing Authority of India.
chimes 21(1): 75-79 Jayaram, K.C. (1999): The Freshwater Fishes of the Indian region.
Grimes,C.B. (1998): Marine Stockenhancement: Sound management Narendra PublishingHouse, Delhi. 395 pp.
or techno-arrogance? Fisheries (Bethesda) 23(9): 18-23 Joshi,C.O. (2004): Systematics andBionomics oftetraodontidsalong
Inasu, N.D. (1993): Sexual dimorphism of a fresh water puffer fish south west coast of India and inland'waters of Kerala. Ph.D.
Tetraodon travancoricusHoraandNair,collectedfromTrichur Thesis, University ofCalicut, Kerala.
district, central Kerala. J. Bombay Nat. Hist. Soc. 90: Kurian,Molly&N.D.Inasu(1997):Sexualdimorphismoftwoinland
523-524. edible catfishes Ompokbimaculatus (Bloch) andHorabagrus
Inasu, N.D. (2004): Sexual dimorphism in Horabagrus brachysoma brachysoma (Gunther).J. Inlandfish. So.c. India29(2): 34-39.
J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007 227
.
MISCELLANEOUS NOTES
MartinMoe,C.(2002):TheBreeder’sNet.Advancedaquarist’sonline Fishing chimes 24(12): 49-53.
magazine. Pp. 216. Talwar, P.K. & A.G. Jhingran (1991): Inland Fishes of India and
Pathani, S.S. & S.K. Gaur (1989): Secondary sexual dimorphism in Adjacent countries, Oxford & IBH Publishing Company, New
Beriliusbendelisis(Ham.)andBeriliusvagra(Ham.).IndianJ. Delhi. 878 pp.
Anim. Sci. 59(12): 1580-1581. Tessy Mandy, J. & N.D. Inasu (1998): Sexual dimorphism ofmarine
Rao, G.R.M. (2000): Advances in Inland fisheries research In: (Eds: perch,Priacanthushamrur(Cuv. &Val.).J. BombayNat. Hist.
Gopakumar, K., B.N. Singh & V.R. Chitrasni) Fifty years of Soc. 95(1): 132-134.
fisheries research in India. Indian Council of Agricultural Thampy, D.M. (2002): Role of professionals in the development of
Research, New Delhi, 124pp. inlandfisheriesinIndia.Pp.351-358.In:RiverineandReservoir
Reimchen, T.E. & P. Nosil (2004): Variable predationregimes predict fishes ofIndia. SocietyofFisheriesTechnologists (India).
MR
the evolution of sexual dimorphism in a population of three Thoblas, (1974): Observations on the morphological variations
spine stickleback. Evolution 58(6): 1274-1281. in Puntiusfilamentosus (Val.) Family Cyprinidae: with a
Roychan,K.J.(2005):Secondarysexualcharactersinfreshwaterfishes. redescriptionofthe species. J. Inlandfish. Soc. India6: 45-50.
22. NEW RECORDS OF TWO EEL FISHES FROM GREAT NICOBAR ISLAND,
BAY OF BENGAL
1
R. Rajaram2-4,M.Srinivasan2,S.AjmalKhan2,L. Kannan2-5,D.V. Rao3andKamalaDevi3
'Accepted September 10, 2004
-Centre ofAdvanced Study in Marine Biology, Annamalai University, Parangipettai 608 502, Tamil Nadu, India.
’Zoological Survey of India, Andaman and Nicobar Regional Station, Port Blair, India.
4Email: [email protected]
’Email: [email protected]
Highlydiversifiedfishesoccurringinthecoastalwaters filamentous appendages; tube of anterior nostril with
and coral reef areas of the Andaman and Nicobar Islands foliaceous appendages; dorsal and anal fins well developed,
have been a source of continuous biodiversity research by origin of dorsal fin well before gill openings; pectoral fins
various ichthyologists (Rao etal. 2000). During the present absent; dorsal, anal and caudal fins confluent. Body bluish
study, detailed investigations on the fish samples collected black with yellow dorsal fin, anal fin black; both dorsal and
from the coral reef areas around the Great Nicobar Island analfinswithwhitemargin.
were made. Atotal of 176 species offin fishes belonging to Habitat: Foundinsandybeachareas.
106genera,71 familiesand 15orderswererecorded.Among Distribution:CentralandwesternPacifictoIslandsof
these,twospeciesarenewdistributionalrecordstoAndaman IndianOcean.
andNicobarIslands,BayofBengal.Thedescriptionsofthese
two fishes belonging to families Muraenidae and Family:Moringuidae
Moringuidae, classified underthe orderAnguilliformes, are 2. Black-tailedThrushEelMoringuabicolorKaup 1856
given here. MoringuabicolorKaup 1856,Cat.Apod.Fish.Pp. 107.
Rataboura bicolor: Munro 1982. The Marine and
SystematicAccount FreshwaterFishesofCeylon. Pp.63.
Order: Anguilliformes Materialexamined:Onespecimen, 16.ii.2003,Kichad
Family:Muraenidae Nullah,westcoastofGreatNicobarIsland,Reg.No.5168(B).
1. RibbonEelRhinomuraenaquaesitaGarman 1888 Description (mm): Total length 685; eye diameter 3;
RhinomuraenaquaesitaGannan 1888. Bull.Essex.Inst. distance from snout to dorsal 630; depth of the body 14;
Pp. 114. length of pectoral fin 6; caudal 5; dorsal 55; ventral 50;
Rhinomuraenaquaesita: 1990.Randalletal.Fishesof 5 conical and short teeth arranged in single rows in jaws.
theGreatBarrierReefandCoralSea.Pp.41 Body elongate, worm-like and cylindrical; posterior nostril
Materialexamined:Onespecimen,204.2003,Lashman opens in apore in front ofeye; eyes small and covered with
beach,eastcoastofGreatNicobarIsland,Reg. No. 5167(A). skin;lowerjawprojectingalittleinfrontofsnout;lateralline
Description (mm): Total length 755, eye diameter 4, present; dorsal and anal fins small, confined to tail region;
distance from snout to dorsal 30, body depth 15, caudal fin caudalregionformingapointwithwhichdorsalandanalfins
length4, length ofdorsal fin 725, ventral 510. Body slender are confluent with caudal fin. Upper halfofbody brownish
andelongated;cleftofmouthreachingfarbehindeye;triserial and lowerhalfpale yellow, caudal fin blackish with a white
villiform teeth in both thejaws; tip ofjaws with barbel-like edge,otherfinslightyellow.
228 J. Bombay Nat. Hist. Soc., 104 (2), May-Aug 2007