Distribution of juvenile cephalopods collected during a survey on tuna larvae in the Mediterranean Sea (1994)

2009·5.2 MB·English

by  Gian Maria Balducci

Boll. Malacol., 45 71-80(suppl. 2009)
Distribution of juvenile cephalopods collected during
a survey on tuna larvae in the Mediterranean Sea (1994)
Gian Maria Balducci* (El) & Corrado Piccinetti*
* SocietàCooperativa Abstract
ProgettoBlu, (C.I.R.S.PE, Plankton samples were collected during a survey on tuna larvae carried out throughout the Mediterranean
CentroItalianoRicerche Sea from the 7Julytothe 5 August 1994. Two double oblique hauls, with a BONGO 60 plankton netand a
eStudi perla Pesca), FAO plankton net, were carried out in 302 stations. The examination of the BONGO collected samples re-
Strada NazionaleAdriatica
Sud,44/8, 61032 Fano vealed 542juvenilecephalopodspecimensof 14differentspecies. Resultsshowedthatjuvenilecephalopods
(PU), Italy, are a significant part of the zooplankton in the epipelagic stratum of the Mediterranean Sea. Theyare rep-
[email protected] resented mostly by members of the families Onychoteuthidae and Enoploteuthidae. Juveniles of Chtenop-
13 Corresponding teryxsicula were also abundantly collected.
( )
Author
Riassunto
*Dipartimentodi Biologia
Evoluzionistica Il Laboratorio di Biologia Marina e Pesca di Fano, nell'ambito della Commissione Internazionale per la Con-
Sperimentale, Università servazione dei Tunmdi dell'Atlantico e del Mediterraneo (ICCAT), ha condotto una campagna di pesca spe-
degli Studi di Bologna, rimentale in 302 stazioni, utilizzando due retini per plancton, BONGO 60 e FAO. Le stazioni, distribuite su
Laboratorio Biologia tutta l'area mediterranea, erano distanti fra loro 15 miglia nautiche. I prelievi, svolti sia nelle ore diurne che
Marinae Pesca di Fano, in quelle notturne, hanno interessato il bacino orientale, nel periodo dal 17/6/94 al 7/7/94(stazioni 1-1 16),
VieAdriatico 1/N, 61032 e quello occidentale, dal 23/7/94 al 5/8/94 (stazioni 140-302). Le pescate sono state effettuate in doppio
Fano(PU), Italy, obliquo, raggiungendo una profondità media di 70 m Per ogni campione, sono stati separati gli stadi gio-
[email protected]
vanili dei cefalopodi dal resto del plancton. L'identificazione si è basata soprattutto sull'analisi morfologica
ed ha preso in esame esclusivamente il materiale raccolto dal BONGO 60. In tutto sono stati catturati 542
giovani planctonici, per 115 dei quali non è stata possibile l'identificazione a livello specifico. Sono state
individuate 14specie. Le modalità con cui sono state eseguite le pescate non consentono un'analisi precisa
dei ritrovamenti in base alla profondità. Dalla suddivisione in fasceorarie delle pescateeffettuate durante la
campagna è emerso che una componente significativa delle catture è stata registrata nelle ore notturne.
Tenendocontodella profondità media raggiunta dal retino, si puòsupporreche i giovani cefalopodi risieda-
no a profondità maggiori nelle ore diurne portandosi verso la superficie durante la notte. Nella regione
epipelagica del Mediterraneo, lungo i punti presi in esame dalla campagna, i giovani cefalopodi costituisco-
no una componentesignificativa dellozooplancton, efra essi si nota una predominanza di Onicoteutidi edi
Enoploteutidi ai quali si deve aggiungere la presenza massiccia di giovani di Chtenopteryxsicula finora non
evidenziata in letteratura.
Key words
Juvenile stages, Cephalopoda, Mediterranean, plankton, distribution.
Introduction whether the very young cephalopods may be defined
"larvae". Indeed asforthecephalopodsthisdefinition is
Juvenilecephalopodsplayanimportantrole in the feed- not completely right because their metamorphosis does
ingrelationand in thetrophicweb ofthepelagicmarine notpass througha second stage (Boletzky, 1974).
ecosystem (Amaratunga, 1983). However, young forms Oldstudiesonspecimenscollectedin theMediterranean
are still not known for many species and the identifica- Sea are useful to the identification of the juvenile stages
tion of young stages often does not reach the desired ofsomespecies(Naef, 1923;Issel, 1920a,b, 1925;Degner,
taxonomic level (Sweeneyetal., 1992). 1925; Sanzo, 1929). Roper (1974) gave an importantcon-
Juvenile cephalopods show many features that are not tribution to the knowledge of vertical and seasonal dis-
present in adult stage (Okutani, 1987): compared to tribution of pelagic cephalopods in the Mediterranean
adults they have different body proportions, a different Sea. A survey followed by the collection of juvenile ce-
mantle shape, often with rudimental fins and different phalopods was carried out by Sanchez and Molí (1985)
body chromatophores pattern. Young stages of many along the Mediterranean coast ofSpain, and three more
species have stalked eyes and quite often a different recent surveys have been carried out in the Aegen Sea
number of photophores than in the adult phase. How- (Lefkaditou etal., 1999 and 2005; Salman et al., 2003).
ever, these characteristics are very useful for juvenile All these studies gave a precious contribution to the
identification (Okutani, 1987). knowledge on the ecology, distribution and identifica-
The post-hatching cephalopods growth has been ana- tion of young cephalopods in the Mediterranean Sea.
lysedbymanyauthors and oneofthe importantcontro- However,thesestudies tookintoconsiderationa limited
versies concerns the validity of the term “larva" and area. Following the survey carried out by Roper (1974),
which took into consideration adult specimens too, no vessels, 22 hauls (station nos. 117 to 139) were carried
otherplankton survey throughout thewhole Mediterra- out simultaneously by both vessels, from the 19 July to
nean basin is reported in the scientific literature. the 20July.
The aim of this paper is to contribute to the knowledge From the 17June to the 7July, the Italian vessel worked
of the distribution of juvenile cephalopods in the Medi- in the eastern Mediterranean basin, from the 23 July to
terraneanSea, with theidentification ofmany youngce- the5August, in thewesternbasin. The data collected in
phalopods stages collected during an ICCAT interna- theintercalibration-zonewerepooledtothoseoftheeast
tional research survey on tuna larvae carried out by the side for their quantitative assessment.
FanoMarineBiologyLaboratory.TheobjectiveoftheIC- During the survey, the hydrological parameters salinity
CAT plankton survey was to determine the distribution and oxygenlevel weresampledbythe Idronautprobe.
and theabundanceoftunalarvaeinthisbasin.Theexpe- Ineachstation,theplanktonnetsweredouble-towedob-
dition provided an occasion to examine the plankton liquely between the surface and the depth of 70-80 m.
Gian
samplescollectedin302stationsdistributedinthewhole Eachnetwasequipped with a mechanical flow-metre to
Maria Mediterranean Sea, in the summer of 1994. The survey recordthevolumeoffilteredwaterand a depth-finderto
has investigated mainly theepipelagicwater layer. With estimate the tow depth. Through the combination be-
Balducci this study we aimed to examine the presence of young tween the volume of water filtered and the maximum
& cephalopods in this area according to the different light depth reached in each haul it is possible to evaluate the
conditions ofa 24-hourperiod. numberofjuvenilescollectedperunitsurface (m2). Fora
Corrado best representation of data we have multiplied the re-
sults by 1,000 and we have showed the richness as N
Material and methods specimens/1,000 m2
.
Piccinetti All samples were fixed and preserved in 5% seawater
Thejuvenile cephalopods were collected in the summer formalin forthesubsequentlaboratory processing. Sam-
of 1994, from the 17 June to the 5 August, during an in- ple analysis and juvenile cephalopod identification was
ternationalresearchsurveyontuna larvaecarried outin carried out with an optical microscope. Each preserved
theMediterraneanSea. specimen was measured (dorsal mantle length, ML).
The research was carried out by two vessels, the Italian Thespecieswereidentifiedaccordingto Issel (1920a,b,
Copernaut "Franca" and theJapaneseSoyuMaru, along 1925), Naef (1923) and the key in the manual for "lar-
the Mediterranean area, in pre-established 302 stations val" and juvenile cephalopods identification (Sweeney,
15 miles apart of one another. In each point two double 1992).
oblique hauls, the first one with a BONGO 60 plankton
net and the second one with a FAO plankton net, were
carried out. The bongo 60 plankton net is composed of Results
two 60 cm diameter mouths fitted with 335 p and 505 p
mesh nets respectively; the FAO plankton net has a sin- Juvenile cephalopods were caught in 194 stations, i.e.
gle 100 cm diameter mouth fitted with a 505 p net. 64% of the total stations. In these stations, in all 542
In this study we took into consideration all the samples youngcephalopods were caught.
collected by the BONGO 60 by the Italian vessel. This The identification of 115 specimens was impossible, ei-
vessel worked continuously during the survey period, ther because they were too damaged during the haul or
that is day and night; therefore the hauls were carried badly preserved, or because of their too early develop-
out with different light conditions, during daytime, at mentstage.
sunset, at night and at sunrise (Tab. 1). The collected The sampling depth was in between 38 and 140 m; any-
samples were separated into three different light inter- way most of the hauls were carried out in the depth
val: from 8 am to 6 pm (high light intensity), from 8 pm range from 60 to 100m. Thebongo 60 reached the depth
to6am (low lightintensity),from6amto8amand from of100 mordeeper in50 stations.
6 pm to 8 pm (intermediate light intensity) (Tab. 1). The low light positive stations are included in the 70-90
m
In a specific area of the Ionian Sea, "inter-calibration depth range. Thenetreached a depthdeeper than 100
m
zone" in order to calibrate the collected data by the two in 7 night positive hauls and in 14 positive daytime
Nofstationateach lightintensityinterval
Mediterraneanzone Period N ofstations
High Intermediate Low
East 17.6.94-7.7.94 116 51 20 45
Inter-calibration 19.7.94-20.7.94 23 3 7 13
West 23.7.94-5.8.94 163 64 28 71
Overall 17.6.94-5.8.94 302 118 55 129
Tab. 1. Numberofstationssampledduringthesurveyperiod in each areaand in each light interval.
72 Tab. 1. Numerodi stazionicampionateeperiododi campionamentoinciascunaarea ed inciascunacondizionedi luce.
stations. However, oblique tows do notgive an accurate appearsthattheintensityoflighthasan influenceonthe
informationon the depthofcatches. numberofjuvenilescaught (P < 0.001).
The number of positive stations in the three different Moreover, threedifferentintervalsofrichnesshavebeen
lightconditions isshown in Fig. 1. identified: 1) 50 < Nspecimens/1000m2< 200; 2) 200< N
The highest number of positive stations is in the low specimens/1000 m2 < 700; 3) N specimens/1000 m2 >
lightinterval:93positivestationsforyoungcephalopods 700.
outof 129 sampled stations. The maps in Figs. 3 to 11 show the distribution of the
The following percentages of collected juveniles cepha- collected species (positive stations along the sampling
lopods are: 53% caughtduring thenight, 30% in the day grid). In the maps, the respective richness interval for
light, and 17% with intermediate light conditions (Fig. each station, regarding the most abundant species, is
2). Tab. 1 reports the total numberofjuveniles caughtin shown.
each light interval; 287 young specimens were collected In Fig. 3 the richness distribution (juvenile cephalo-
m
at night. However the number of hauls carried out in pods/1000 2 along thesampling grid according to the
) Distribution
each light interval is different and the majority of hauls three interval pre-established is shown.
were carried out at night. We tested such data by the Accordingto thedata presented in Tab. 2, a largerquan- of
Pearson's /2-test to verify the significance, if any, of this tity of young cephalopods was collected in the eastern
difference. The %2-test showed that there is no causal re- basin. Inthisbasinthereare 15stationswith therichness juvenile
lation between intensity of light and the probability to in the highest interval, 12 ofwhichare in theIonianSea,
catch young cephalopods (P > 0.05); on the contrary, it whereas in the western basin such a richness is reached
cephalopods
$$ high
&
intermediate collected
Í2 low
during
a
survey
on
tuna
Fig. 1. Numberofpositivetows/total numberoftowscarriedoutin each larvae
lightinterval.
Fig.2. Percentageofcatchesaccomplished ineach lightinterval. in
Fig. 1. Numero di cale positive/numero totale di cale effettuate in cias- the
cunacondizionedi luce. Fig. 2. Percentualedicatturerealizzateinciascunacondizionedi luce.
Mediterranean
Sea
(1994)
Fig. 3.Abbondanzacomplessiva(esemplari/1000 m2)del giovanili di cefalopodi raccolti lungo la grigliadicampionamento. 73
only in 7 stations. As regards the West Mediterranean, the Ustica island and theAeolian Archipelago. The low-
we have recorded the highest number of catches in the estquantityofcatcheswasrecorded inthestationsinthe
Sicily Channel and in the southern Tyrrhenian between north-western side ofthebasin.
Mediterraneanarea Lightintensity MLrange
N
Species
mm
West East interm. high low
Heteroteuthisdispar(Riippell, 1844) 12 11 1 - - 12 3-5
Ancistrocheiruslesueuri(d'Orbigny, 1842) 3 2 1 - 1 2 5-9
Enoploteuthidaespp. 75 34 41 18 22 35 1.6-8
Gian Brachioteuthisriisei(Steenstrup, 1882) 18 4 14 - 4 14 1.2-15
Maria Chiroteuthisveranii(Férussac, 1835) 3 1 2 - 1 2 8-35
GaliteuthisarmataJoubin, 1898 6 - 6 2 3 1 3.6-8
Balducci
Chtenopteryxsiculo (Vérany, 1851) 106 16 90 20 29 57 1.2-6
&
OctopoteuthissiculoRiippell, 1844 36 27 9 18 1 17 1-3.6
Corrado
Ommastrephidaespp. 27 18 9 2 6 19 1.2-4.4
Onychoteuthidaespp. 111 68 43 6 41 64 1.8-6
Piccinetti
ThysanoteuthisrhombusTroschel, 1857 6 - 6 1 4 1 2.8-8
OctopusdefilippiVérany, 1851 1 1 - - 1 - 2.8
OctopusvulgarisCuvier, 1797 11 7 4 1 6 4 1.2-3.2
Scaeurgusunicirrhus (DelleChiaje, 1840) 12 6 6 1 5 6 1-3.6
Unidentified 115 44 71 24 38 53 -
Totalcephalopods 542 239 303 93 162 287 -
Tab. 2.Cephalopodspecies, numberofindividualscollected perspeciesinthetwoMediterranean basinsand ineach lightintervals, andtheirsizeranges.
Tab. 2. Speciedi cefalopodi, numerodi individui raccolti perspecienei duebacini mediterranei inciascunacondizionedi lucee lorotaglie.
Fig. 4. Distribution of Heteroteuthis disparand most rare species: Thysanoteuthis rhombus, Galiteuthisarmata, Ancistrocheirus tesueurii, and Chiro-
teuthisveranii.
Fig.4. DistribuzionediHeteroteuthisdisparedellespeciepiù rare: Thysanoteuthisrhombus, Galiteuthisarmata,AncistrocheirusiesueuriieChiroteuthis
74 veranii.
Distribution
of
juvenile
cephalopods
collected
Fig. 5. Distribuzioneeabbondanza(esemplari/1OOOm2)di Enoploteuthidaespp during
a
survey
on
tuna
larvae
in
the
Mediterranean
Sea
(1994)
Fig. 6. DistribuzionediBrachioteuthisriisei.
The tableshows thespeciescollected and the numberof spp., and Chtenopteryx siculo) were also collected abun-
specimensbelongingtoeach species,theirsize(ML), the dantly in otherlight interval.
area of captures and the relative light intensity during The quantitative data for all the collected species are
thehauls. Itappearsthat themajorityofspecimenswere shownin Tab. 2.
caught at night. However, juveniles of the most abun- The followingspecies deserve a more detailed analysis.
dant species (Enoploteuthidae spp., Onychoteuthidae
Family Enoploteuthidae areratheruniformlydistributed,excepttheareabetween
the Island of Crete and Cyprus. We found some speci-
In the Mediterranean Sea, this family is represented by mens in the western basin along the west coasts of Sar-
two species (Mangold & Boletzky, 1987): Abralin veranyi dinia,intheTyrrhenianSeaandalongtheTunisiancoasts
(Rüppell, 1844) andAbraliopsis morisii(Verany, 1839). We (Fig. 5). Mostcollected specimensweretoolittle (1.6to6
found 75specimensbelongingtothisfamily,41 ofwhich mm ML) to allow any identification to the species level;
mm
collected in the East Mediterranean and 34 in the West the only specimen large enough to be identified (8
Mediterranean. In the east side of the basin the catches ML) was in abad state ofpreservation.
Gian
Maria
Balducci
&
Corrado
Piccinetti
Fig. 7. Distribuzioneeabbondanza(esemplari/IOOOm2)di Chtenopteryxsicula.
76 Fig. 8. Distribuzioneeabbondanza(esemplari/1000m2)di Octopoteuthissicula.
Family Ommastrephidae odessagittatus (Lamarck, 1798). The Rhyncoteuthis iseasi-
lyrecognizablefromjuvenilecephalopodsofotherfami-
Theearlyjuvenile stage of this family was named Rhyn- lies, but it is very difficult to distinguish between the
coteuthisbyChun(Naef, 1923). IntheMediterraneanSea, young stages of the different ommstrephid species be-
this family is represented by four species (Bello, 2003): foretheyreachanadvancedstage(Naef, 1923).Wefound
Ommastrephes bartramii (Lesueur, 1821), Illex coindetii 18 specimens in the west side of the basin and 9 in the
(Verany, 1839), Todaropsis eblanae (Ball, 1841), and Todar- east, all ofthembetween 1.2 and 4.4 mm ML(Fig. 9).
Distribution
of
juvenile
cephalopods
collected
during
a
survey
on
tuna
larvae
in
Fig. 9. Distribuzionedi Ommastrephidaespp. the
Mediterranean
Sea
(1994)
Fig. 10. Distribuzioneeabbondanza(esemplari/1000m2)di Onychoteuthidaespp. 77
Gian
Maria
Balducci
&
Corrado
Piccinetti
Fig. 11. Distribuzionedi Octopoda.
Family Onychoteuthidae Teuthoids, i.e. the majority of collected specimens, does
notallow any highly detailed information.
In the Mediterranean Sea, this family is represented by The richness of juvenile cephalopods is higher in areas
two species (Mangold & Boletzky, 1987): Ancistroteuthis that are generally known as strategic for many Mediter-
¡ichtensteinii (Férussac, 1835) and Om/choteuthis banksii ranean species: the Ionian Sea between the Sicilian and
(Leach, 1817).mAlml thecollected specimenshavea sizebe- Calabrian coasts and in the Sicily Channel, according to
tween 1.8 e 6 ML, whereas species identification is datathatshowhowcephalopodstakeadvantageofhigh
mm ML
possible only for specimens larger than 11 biological productivity and hydrographic regimes that
(Sweeney et al., 1992). The specimens belonging to this achievea fastgrowth duringtheirshortlifespan (Lefka-
family make up the largest fraction ofjuvenile cephalo- ditouetal., 1999).
pods collected in the survey. We netted 68 specimens in Wecan state thatthe species ofOnychoteuthidae spawn
the west side ofthebasin and 43 in the east, distributed in the summer in all the Mediterranean basin, particu-
in 60 stations (Fig. 10). larly in the Ionian Sea, and their juvenile stages follow
the adult mode oflife and are concentrated in the upper
m
100 ofdepth (Roper, 1974).
Discussion The results obtained for Chtenopteryxsicula suggest that
this species spawns in this part of the year in all the
According to the results, we can state that juvenile ce- Mediterranean and prefers central-southern waters;
phalopods are quite common in the epipelagic zone of moreover, their juvenile stages too follow the adult
the Mediterranean where they occur throughout the 24 mode of life and are concentrated in the upper layers
hours. (Roper, 1974).
They are more abundant in the night hours, in accord- TheEnoploteuthidaeappeartopreferthecentral-eastern
ance with the nictemeral cycles described foradults and and south-westernareas.
juvenile stages (Young et al., 1985): according to the re- Octopoteuthis sicula and Brachioteuthis riisei (Fig. 12C)
sultsofmanyauthors on vertical distribution, youngce- have showna spotdistributionalongthesamplinggrid.
phalopod ascend at night towards the sea surface (e.g. The same situation has been observed for the Ommast-
Lefkaditou et al., 2005). rephidae, whichare absent from the southern areas.
Obliquetowsdonotgiveanyinformationonthevertical JuvenilestagesofHeteroteuthisdisparwerefound in only
distribution ofcollected specimens; hence a detailed re- 4stations, 1 in the EastMediterranean and 3 in the West
view ofcatches according to depth is notpossible. Mediterranean. Issel (1925) believes this sepiolid to be a
The relatively small size of juveniles caught might sug- neriticspeciesbutrecentstudieshaveshown a widedis-
gest that the areas of distribution reported coincides tributioninopenwatersathighdepth (Roper, 1974). The
78 with the spawning areas, but the spawning habits of specimens of Heteroteuthis dispar were caught only at
Distribution
of
juvenile
cephalopods
Fig. 12. "Larval" stages. A. Ancistrocheiruslesuerii(7 mm DML), West Mediterranean, st. no. 221. B Chiroteuthisveranii(8 mm DML), West Mediter-
ranean, st. no. 223. C. Brachioteuthisriisei(15 mm DML),West Mediterranean, st. no. 298.
collected
Fig. 12. Stadi "larvali" A.Ancistrocheiruslesuerii(7 mm LMD), Mediterraneooccidentale, staz. 221 B Chiroteuthisveranii(8 mm LMD), Mediterraneo
occidentale,staz. 223. C. Brachioteuthisrisei(15 mm LMD), Mediterraneooccidentale,staz. 298.
during
a
night, when they shift up toward the surface (Roper, Issel R., 1920a. Primocontributoallaconoscenza dellosvilup-
survey
1974). ponei Cefalopodi Mediterranei. RealeComitato Talassografico
The most rarely caught species, namely Thysanoteuthis Italiano, 73. on
rhombus, Galiteuthis armato, Ancistrocheirus lesueurii, and Issel R., 1920b. Distribuzione e significato biologico del pig- tuna
Chiroteuthis veranii, were collected in a small number of mento cefalico nelle giovani larve di Cefalopodi egopsidi.
RealeComitato talassografico italiano, 76. larvae
specimens (Fig. 12).
We can lastly state that in the epipelagic layer of the IsselR., 1925.Contributoallaconoscenzaecologicadellelarve in
Mediterranean Sea juvenile cephalopods are a signifi- planctonichediCefalopodi. RealeComitato TalassograficoItal- the
iano, 120.
cantpartofthezooplankton.Theyarerepresentedabove Lefkaditou E., Papaconstantinou C. & Anastasopoulou
all by the Onychoteuthidae and Enoploteuthidae, in ac- K., 1999. Juvenile cephalopods collected in the midwater
Mediterranean
cordance with the information reported by Issel (1925). macroplankton over a trench, in theAegeanSea (northeast-
Moreover, we have to point out the abundant presence ernMediterranean).IsraelJournalofZoologi/,45: 395-405.
ofjuvenilesofChtenopteryxsiculo. Lefkaditou E., Siapatis A. & Somarakis S., 2005. Juvenile Sea
planktonic cephalopods sampled off the coasts of central
Greece (Eastern Mediterranean) during winter. Phuket Ma- (1994)
Acknowledgements rineBiologyCenterResearch Bulletin,66: 259-265.
Mangold K. & Boletzky S.v., 1987. Céphalopodes. Fiches FAO
d'indentification des espèces pour les besoins de la peche.
Theauthorswishto thank Mrs. C.Angeloniand Mrs. G.
(Revision I). Mediterranée et Mer Noire. Zone de Pèche 37.
Manfrin for their help with the translation and revision
FAO, Rome: 633-714.
ofthe text. Naef A., 1923. Die Cephalopoden. Fauna und Flora des Golfes
von Neapel,35 (1, 1).
O'Dor R.K., Helm P. & BalchN., 1985. Can Rhyncoteuthions
References suspensionfeed? (Mollusca,Cephalopoda). VieetMilieu,35:
267-271.
AmaratungaT, 1983. TheroleofCepholopodsinthemarine OkutaniT., 1987.Juvenilemorphology. In BoylePR. (ed.),Ce-
ecosystem. In Caddy J.F. (ed.). Advances in assessment of phalopod lifecycles. Voi. 2. AcademicPress,London:32-44.
worldCepholopodsresources.FAOFisheriesTechnicalReport, RoperC.F.E., 1974. Vertical and seasonal distributionofpelag-
231: 379-415. iccephalopodsintheMediterraneanSea.Preliminaryreport.
Bello G., 2003. Thebiogeography of Mediterranean cephalo- BulletinoftheAmericanMalacological Union,May 1974: 27-30.
pods. Biogeographia,24: 209-226. SalmanA., KataganT. & Benli A.H., 2003. Verticaldistribu-
Boletzky S.v., 1974. The "larvae" of Cepholopoda: a review. tion and abundance ofjuvenile cephalopods in theAegean
ThalassiaJugoslavica, 10: 45-76. Sea. ScientiaMarina,67: 167-176.
Degner E., 1925. Cephalopoda. Report on the Danish Oceano- Sanzo L., 1929. Nidamentopelagico,uovaelarvedi ''Thysano-
graphic Expedition 1908-10 to the Mediterrenean and adjacent teuthis rhombus" Troschel. Reale Comitato Talassografico Ita-
seas,9,Yol. II. Biology,C.l: 1-94. liano, 161. 79
Stephen S.J., 1985. The distribution oflarvaeofthegenus Oc-
topoteuthis Rüppell, 1844 (Cephalopoda, Teuthoidea). Vie et
Milieu,35: 175-179.
Sweeney M.J., Roper C.F.E., Mangold K.M., Clarke M.R. &
Boletzky, S.v. (eds.), 1992. "Larval" and Juvenile Cephalo-
pods:Amanualfortheiridentification.SmithsonianContribu-
tion toZoology,513: 282pp.
Young R.E., Harman R.F. & Mangold K.M., 1985. The eggs
and larvae of Brachioteuthis sp. (Cephalopoda, Teuthoidea)
fromHawaiianwaters. VieetMilieu, 35:203-209.
Gian
Maria
Balducci
&
Corrado
Piccinetti
Lavororicevuto il 20 luglio2009
80 Lavoroaccettatoil 20 luglio2009