Predation by muricid and naticid gastropods on the Lower Tortonian moIlusks from the Korytnica clays

Vol. 24, No. 1

acta

poIOfI'.

polon ••

Warsz.awa 1974

Predation by muricid and naticid gastropods on the Lower Tortonian moIlusks

from the Korytnica clays

AmI1RAOr: Traces 0If the predation by boo.ing gastropods, very common OIl the Lower Tortondan gastropods, pelecypods and scaphopods from. the Korylnica .clays on the southern slopes 01. the Holy Cross MW;, Central Poland, have been ascribed to !!le adivlity of four murlcld and five naticid species. A very strong dtflferen- t1atioo of the proneness of particular species to be attaeked by predatory boring;

g·astropods has been shown by a statistical anaJ.ysis of more than 20,000 specimens of over 120 species. In tbas respect the eharacler of di!f'ferentatloo. of la!l.'ge tax<Jnomic. and eool·ogi:cal groups suggests that it ;results not &0 m~h from the eilbology cl ·the jpl"edators as from the eoo1ogy of their potentia1 prey .. 'I'Ibe ratio of the numbers of the naticld and muricid prey within the range of large tax;o- nomic alld eoological groups indd.cates divergent interests at the two groups

or

lPl'edatory boring 19astropOdsaDd an only small extent of their compet'itian.

IN.J;UtODUCTION

Traces of the predation 'by boring gastropods are very common among the abundant and. excellently preserved Lower Tortonian mol- lusks which occur in the Korytnica clays (cf. Friedberg 1911-1928, 1934 -1936, 1938; KowaleWSld 1930; Bahllk & . Ja'lrulbowski 1968; Rad-·

wanski 1969, 1970; Baluk 1971, 1972, 1974). They bave been found in gastropods, pelecypods arid scaphopods, but never so far in chitons.

They are observed in the form of more or less regular, round or elliptic holes, through which the predatory gastropods reached with their- proboscides the inside of the shell and .the soft flesh of their prey. As the identical traces are well known in the Recent fauna, .the authors have undertaken the comparative studies to recognize both the nature

:250 ANTONI HOFFMAN, AlNDRZEJ' PISEB.A. 80 IolABOllN B11BZ'KIEWTCZ

of the borings as well as et'hology of the predators and ecology of their prey: '1'he particulaT species that are the prey of predatory gastropods have been examined statistically to obtain as far as possible the most reliable data on geneTal proneness of these species to the attack of predators. The obtained results are regarded to be instructive for paleo-

-syneoological analysis of othe IIllOllusk communities that settled in the Lower Torlonian environment yielding the remar.ka,bly foSsiliferous Ko- :rytnica clays.

Acknowledal!lmeflts. The autbol's are JnOObted to Dr. W. Bahlk, University oI W8l"9aoW, and !Dr. G. Jakuoowski, Museum oI the Earth (;Polish Academy 01.

;Sciences), for making available their collec1lions of the Korytnlca mollusks and .beIlpful adv.ilCes. Thanks a1'e also due ~o Dooent A. Rad'ml6slti, Unilversity 0If War- saw, for critical reading of the. manuscript

:romDATORY BORING GASTROPODS

Many laboratory studies WeTe unaen;aKen on toe e1;nolOgy .and manner of boring in the. Recent carnivorous gastropods (Ziegehneier 1954, Wells 1958, Paine 1963). Almost identical traces, frequently met with in the Tertiary and sporadically in the Cretaceous, are generally considered to 'be the result of the· acUvity of identical groups ,cif gastro- pods with the Rec~t ones, viz. Muricacea and Naticacea. On the ,other ·hand, Paleo~oic traces similar in characteT probably represent the -effects of boring of other animals (Carriker & Yochelson 1968),altho~gh

.sometimes they are ascribed to the activity of gastropods different than Muricacea and Naticacea; viz. the genus Subulites (cf. CameroIl 1967).

In ecologica1 and padeoecological l~terature, there occur frequent ,ambiguities and often it is' not clear whether the authors deal with the predatory gastropdds which directly attack: the soft 'body of their prey or with those securing their food by.boring the shells. It is beyond any doubt, however, that the latter manner of attacking is observed in various genera of Muricacea (Murex, Ocenebra, Pteropurpura, Thais, Urosalpinx) and Naticacea (Ampullina, Euspira, Natica s.l.). Fischer (1922, 1966) mentions that also some of rthe Recent species of NaS8a are boring predators, but he is very cautious concerning such a poSsibility :in the· case of older geological epochs. More explicit in this respect is Mila-

shevich (1916, fide DavitaShvi'li & Mer'k'li,n 19608), who maintains that .Nassa reticulata (Linnaeus), the species absent at Korytnica, bores. the .shells of thin-va;lved pelecypods in search of food. All other species of .Nassa are, however, treated either as nec:rophags or predators directly .attacking their prey. Not quite clear is the status of such genera .as ColumbeUa,· Euthria and FUSU8, sometimes mentioned as· boring gastropods (;(FischeT 1922), but in more recent papers (Ziegelmeier 1954,

IFREDATION BY MUlIIIC'll) AND NATJCID GASTBOPODB a51

Carriker & Yochelson 1968, Taylor 1970), there are no suggestions that, except for the Muricacea and Naticacea, any other genera or species are predatory boring gastropods.

Under such circumstances, the authors believe that the boringsof this type found in the Korytnica mollusks may ^be considered as the sy'Inptoms of the predation mostly by following most common at Ko- rytnica (cf. Friedberg 1911-1928, 1938) species of muricids and naticids:

Murex jriedbergi Cossmann & Peyrot, O<!'enebra crassilabiata (Hilber), O. orientalis Friedberg, Natica heiicina Brocchi, N. j08ephina (Risso) , N. miUepuncmta Lamarck, N. p,'Jeudoredempta Friedberg, and N. redem- ta MiCheJ.dtti.

The Recent Muricacea and Naticacea markedly differ from each other· in their mode of life and their borings vary morphologically (Carriker & Yochelson 1968, Taylor 1970).

The Muricacea that bore ·by a rotatory motion of their radulae (cf.

Carriker & Yochelson 1968) belong to epifauna which explains why at Korytnica their borings are so frequently met with at the ·outer margin of shalilowly burrowing pelecypods. The muricid borings in the Korytnica mollus'ks are of a cylindrical shape (PI. 1, Fig. 1), frequently irregular in outline and with jagged margins (PI. 4, Fig. 1). Failed borings. which occur sometimes have matkedly concave bottoms. Sometimes, several borings , are observed on one and the same prey (PI. 2, Fig. 5), which seems to result from the muricids' tendency to the attack in groups (cf. Paine 1963).

Not all species of· the muricids secure their food by boring the shell of prey. Moreover, as follows from laboratory studies on the behavior and manner of attacking prey by Recent species of Murex, borings are made only by young individuals, while the adults are sufficiently strong to open the shells of pelecYl?ods (Wells 1958).

The ~aticacea, 'belonging to infauna, look fur their food and attack prey in the bottom sediment only, and get out onto the surface only un'der unfavora'ble conditions. The strongly de~eIoped foot aliows them to enfold strongly ~heir prey and. Ito handle it as long as it is necessary to find an appropriate place for boring. Thus far, nobody has been able to answer whether Naticacea choose a definite place on the shell of prey or their borings are distributed at random (Carter 1967, Reymoent 1971). They 'bore by a rotatory motion of their radulae and the participation of the sulfuric acid secretion in this process has not so far been confirmed (Ziegelmeier 1954). The naticid borings in the Korytnica mollusks are very regular, wid€'ly conical (pI. 1, Figs 2 and 4). A characteristic, centrally situated boss (PI. 1, Fig. 3) is observed on the bottom of failed borings. Sometimes, several borings are met with on one .and the same prey (PI. 2, Figs ~-3 . and 6-7), and they SIlpposedly·represent either the effect of a prolonged halld1ingof the prey, or U is a matter of pure accident (the group attack is unknown in the~ gastropods). On the other way. as follows from

26J -ANTONI HOFFM.A.N, .A.NDRZEJ PISERA & MABeJ:N R"Y'SZKIEWl!CZ

laboratory studies, the-naticids do -not distinguish between the alive and 'dead -specimens and they ,bore each shell they find, sometimes those previously bored including (Ziegelmeier 1954). 'l'hus far, no species of na ticids are known which would secUTe their food. in other manner..

(BCXRI!NIGS OF iMiUlRlCACEA.AND NATICACEA

As inidicated by the l'eS'ldts of studies on the abundaDit lID'8.tetiatl. from Karyiniocajo the morphologiCal criteria oited a.bove I(Cartilter & Yochelson 1968), although very helpiiul in a correct assignment Off tb'e I~to, an appropriate ,group of !P'l'e4-ators_r are insUiffician1 and frequently ileave a considerable mlllrgin of ,uncertainty. Moreover"

detemr.inilng a <distinct Iboundary seems to !be impossible, since in many ,cases the authors notieed in the borings a gradual passage from the "naticid" type to the '''Inuricid'' one, even when the S8IIIle ;predator had been evidl!lllced - a distinct preference for the place of boring in e.g. Sabatta calUfe,m Boettger or NCI88a schoemi (R. Hioe!rInes & ..AJuiiIngieIr) :iillIdiWltes dDe onJ.y tYPe ICIf a predaitQr (c;f. iPII.. 3, F',b 1-:-'10).

Sometimes, the morphology of the tborings is so closely correlated with the mi'Cl'lOlS1IruJcibuIr'e of rbhe vmeIU 1ihiaJt it. ~y !r,JreO.ludes a oot'Il'eC.t :ildel!1l1li:fiilCa:tiJon of the Ibor:ings on the lbasis of the morphlologicalcriteria expr,essed by CarTiker &

YocheJson ,~1968). [n tbb; Tespect, the genus Corou.la may serve as an example. The V'a.l!ves of these common ,pelecy'pods contain a -characteristic, very haa:d "oonch'f:Dline,r mid-layer <Fischer 1963), which distinctly affects the maDlIler of hDring and, conse- quently, the morp'hology of holes (cf. !Pl. 4). A complete ean.formity of Fischer's drawings and Iborings observed in the Kory1m.dca mateTial (PI. 4, Flgs 3-J1G) with.

the desctiPt;ion {ZiegeJmeier 19.54) ,af the iborings ,of Lu.mJ.tia nitida Donovan has allowed the authors to dassilfy them I8S indUbitably naticid borings. This brdngs in question the aOOllll"acy of TayUOt"'s '(197'1) determinations, ;as a vaat ma.jority of the barings found in these pelecypods wer,e ascrilbed by him to the activ!l.ty of the murioids.

The necessity of an arbitrary oassignment of these, in fact rather few, iboringsr wh'ieh might !be the resUlt of the a.cti.vdty of gastropods different than iMiurdcaoeea and Naticaoea, to these two morphologioal types, is an additional fact-or' decreasing the reldalbillity of the identification.

All these facts ~ause a 'Vast variaibility within the range of the two grou'PIF distinguished .(Iborlngs Of Muricacea and Naticaeea.) and preclude their unequivc>cal delimitation. It :is likely that sdmilar difficulties WeTe faced 'by otheT investigators.

but ail:1 attempts to eetaP.lldsh !betber -crite1"ia 'of identifying bormgs (e.g. the 'diameter of hDle -LReyment 19&3, 1966a, b) ha'Ve so far ifadled to yield soartisfaetory resuilts.

iPlRC»mNIESS OF THlE KORYT.Nl[CA MOu.,USKS'TO THE lA'lTACK BY MiU.RIOIiDS AND NIATICIDS

The proneness of mollUii9ks most COIDmOlO. in the Korytnica clays to the atback by the predatory ibordng gastropods has been S1.Iibjected to statistical analySjs the resultslOlf which are gi'Ven in Table 1. F,or each species ~S()metimes genus) it is shown how ml1iD.y individua~s were oontained in the sample examined. Here, the authors treat eVeTY two ;pelecypod valves as an equivalent ,af OiIle indi'Vidual, assuming that untder Itbe sedimentalry OODJditions of the Korytnica clays (no trampDrtalti:OIO. and,

ACT A GEOLOGICA POLONICA, VOL. 2~ (1, 1974) A. HOFFMAI~t," A. P1SERA & M. RYSZKIEWlCZ

Table 1

Proneness 'Of mollusdts to the aUtack by preda.tory _bOIrillg gasbr·OtPOds in the Lower Tortondan of iKm'ytnica

The &pecies listed In Tables 1.:..a deterantned by Dr. W. Batuk; their taxonomy for arcbaeo- gastr·opods and a pa·rt Of ceenosutropods (Littorlnacea, Rlssoecea, preaented tn BaWk (197'> . Cerithiacea., SClBiacea)

9p.01lls

I

^Por

^0.'"

."lIba .. o:r proportion

I

^~ Ilat1c1d to apeoiMDI auopla in the .. .poo1ae ... o:r tt8IJb4 the oonft4o.ooo 1II1Ir:I.014 inter...l _{VftT ...} t10

IUSROl'ODS : Aonlla aubnUoulata /4'0"~/ •

~. terebz&l1a /II~hdQtt1/ •

t~t;::.J~~tJrO"~ : :

t~= :~ ·1I;.tt&~; : :

~. ourla /lIu~ • • • • • •

~. 1IOutaavJ. ~ /S1oI>wal4/

~. porropl&l'lII /S8IJoo/ • • • .l ... t_lII118 _/~.o/ • •

1!0~ :t..woi.ia· ;iUa;"'k/

~po_u &latus jl!lo_ld/ • •

"taN _bo~ /lIeettl""/ • •

~tla a1lJa:&'u ~ •• hV • • • • Bitt:l.1III ret:l.oulatq .. /u c •• ta/

11. sp1D& /lutso1i/ ••••• ; C .. o .... &1&_ jIIo.otagu/ •• • COzaU .. atnata /11 •• ""'0/ • • • Costa

.i. . . ,.

^{It ,. ,. ,. ,. ,. ,. ,.} ,.

Cor:l.th1opou tu1le:roularU /IIontap/

coritil1u \lu&tlou lIDattpr •••

C1m1llua a.p. ,.,;,.,..,. •. ,.,.

Clafttula "'penlata JJ-rok/

o. n u /11. lIoaz.a ~ ~u:I.II&.1"/

C. larr:I.pta /110_14/ • • • .:.

C. aQr1ioa ~1dJa&er • • • • • • .•

'Col .... 1Iella Ourla /Duj&r4iJo/ •

g:

==~U::-~~ri:

: ... :::

Co ... olll,lU41n;1. Daah~" • • • • • • • • •

g~~ :;~Il~t~ ~o:t~!/. : : : .:.

z .... t. lIarHDd..:I. lB. _mo. '" .luUJ&er/ •.•

ZUls. .uhulata /Do.ooTUj • • • . .lu.liMlla. oOlllllu.o /1110_141 • • .•

.IutIaJ!1a _111 /Uc1 ...

'o ..

^{k:I.j •} . . P:I.01Ia ap. 4:1... • .•••••••

P _ hoo .. 1 Putaoh • • • • • .• • • ••.•

... ...,ta _ .:u..a /11. 1Ioo:r.oo ... .luUJ&eit/

B. Talor1M lB.. a .. :me. '" .l1dJa&er/ _{0 • • :.}

B:l.bllUla 1Iu.oll1 /lIu'tlo1s/ • • • • • • • • •.•

B. _~lata /IIo.neer/·. • • • :.

II1;ppOIWI: .ul.aatus /IIoroo"/if • • • • .•

l!pla T:l.tro .. /IIontaaul • •.• • • . Ju,Ilb1lllla o.l1rIaoI /~"JoWak:l./ •• :.

iT. turr:l.ollla 1I0 ... s:laDu.ll _00· • • • 1IIUUI0nia ao .. lar:I.o /lIubou/ • . KaM.tho Bp. 4:l.T. • • • • •

118_ :r."".trata /.I1o~

Jl:l.tza ;NQt:!.oo.ta Bellar4:l. • • • • • • _ :rr:I.o4b8"&1 C o _ '" '"Trot •.•

.... aa 411~ jDari1»qea/ • • • • .

•• U-1o .. /Chelllli.1o./ • • • • • •• , .•

•• "..Utut1a.la hontlDu./ • • • • I. ...hoonn:l. /8.. lI .. moa A lu1ll&lr/

•• aena101oo.ta /Brorm./ • • • • • •

•• a1orlAt:l.ooata _{lID.Up ..}

•• 100111&:1. /u!:4&.r/ • • • • • • la101aa h.l:l.o1lla lI:roooll1 • .

• • ~0 . . ph1na /BUao/ .•• •

• It Id.l1iJN,nO~ta taaarok • ~ • • .. • I. n4aJQta IUolllllott.1 • • • • • lerit1lla p:I.ota lIiizuall80 .• • • • • 008"'_ Qzaa.:I.lob1ata /8.llll.r/ • • • 0; "or:l.lntal:l.a PJ!:I.I411e;q • • •

Doaneb%a _,p. It. It • It It • It

lezatot ... ·un1oa /Boat1:pr/ • • 1'otaa14 .... _~lla p. 4:l.T. • • • • • •

4:1.&:1.tal:I.I B . . ttpr ••• • •

Pit pl:loo . . BzoODD It It It It • It It It It • It It

l'7"CUl1Da in1:er,ot1llOt .. ~~taguJ •• • • •

=r-_~~~~.

: : :-::: :

a1JI&:I.oula _ Illata buo01.oaa /IIroooh1/ • 1I:I. ... 01lla po4ol:l.oa C o_ •••••

Baba1o:l.a oallUoza 1Io.Upr ••• • •

~~~:~'==~li ib.ieioQi :

_ l a a:pino_ lIDDOll1 • • • • •.• .. • lIell111U1:11Ia .. ltU~tu /BZ'II8111a/ . S.II1o...". a1olooY1pta s..Doo STolU .. 4ertoTlU"1oou. _{_00 •}

8. 1.o8n:l.l /Pu.aoll/ •••••

~il1o.to_ 1r004:I. /&0 ... / • ftre. """.,. ·/.110_14/ •. • • S!OrDats- MftOl1t1aa 1I."pi

S!. UwlDatllla lllz"~'"1 ••

!l .. 1ooUa e1ohal4:l. /11 ... / ••• • • •

!lr14!ono.to .... _111 11. aGO ... s & .lll1ll&Or Td»h1lN p8ryara • ./L1Jmaaua/ .. ^It It It It It

~tOD aft1no

De.... .. . .

!rr:I.ton sp. • • • • • • • • • • fU4101& ,...a1::I.o .. 1& jBeaurot/ •

!ru.rlloolla 8IJl1t:l.ooata /5o.oco/ ••

!ur1to.o1lla soala /l1ohwald/ • •

!Urr1tella baAlaJlllu 8aGoo .

!. 1I1o .... S-1:& .l1011u.14 • T. enD . . CD . . . It It

l'BLBCYPOlJh

~II ... lba 1W004/ • • • • • • • • .lna4aa 411 .... :1.1 /LaIIarok/ • • • • .lno .. :I.a e:ph1p:p~ Umlaou.a • • : CaN1ta _ozaaaa .0rDroula llaTer Cardd,l1II pap:l.llo.1III 1'01:1. • • • • C _ 8r7p/1o:l4a. I.1.oueu • • • Coc1&t1& ape diy. It It It It • It It It It It

CoJ!bula IUk /Ol1Y~.:..:,. • • • • •

:ml!:..t"~1ft.~~.1· /Iio¥.i/

Il1At.lla ant1 .. I.1.oueWl· ••••••

f!""'4~~~ !"~~ioh..;u/ :

Lutet1a n1t14a jB.oUJIs/ • • • • • • •

~t1"ll .ubtrunol1~ta t"1IuJ&ula JillWI.

)lafttrlx lip. diT. It It It It It It It It It

1I0ntaouta old.pa 0 0 _ •••

K. f.l"J!U&1A08& Kontap • • • •

.1 "OJl1l8

."oulaD&

_rt Str1azo& ~ Iiuoula nucleus Pbaoo:l4as _.101 1I10llelotU •_... IINlUla •• a:p1D.1.t'eZ'a lIonta,au • • • lII .a . . :r1'8l1l1. /Cllellll1ts/ • • laota& l.aria /Sownlllr / • • • lla .... &1.oa11 • /l4m1IMWI/. • • lL1nDaeua/ •• • • • • .l101lwald • •• •• •

IIC.UBOPODB:

DentaliDII :rc.B1la _·/S~.ter/

• • • • l!'1DtUr:1.8 .. 100 ... 1110 .. /II •• tteer/ • • • •

. : I

)1 146 1.1 43 tt, 49 89

~11 1~

.. 1U 190 '90 192 61 178 228 98 220 )0 193 201 209 1»

1se 22 622

2'

HO '9

» 47 20)

« 67 )20 126

'0

81

"

24 24 101 81

"

12' )9

e 81 42 U ,1t 62 50 1"

'47

'2

6:J 81 614 189 202 428

1"

246 40 46 311 84 27)

'1

73 120 )2 618 1860 1'0

1f, '1 402

"I 41 80 1)6 2' .u

1'4 162 212 190 39 24 98 266 41 1229 se

112 120

'"

⁴³

_'2

)4 1)' ~

22 92' 17 25 48 311 2J

."

,.

28 20 '2 3' 84 .111

60 113 920 40

"2

664

,

8 12- 22- 4 12 1 16 22-

,. _,

9 2 1) 13 19 2' 8 1) 1, 12 12 9 2 4

;) 11 4 2.3 19 )0 9 27 'l 17 21 10 o

6 8 4

"

17

,

;)

, l'

8 34 10

,

7

·16 U 10

8 10 7 8 9 11 11 9 4

•

13 20

)

10 17 U. 41 o

12 2- 24 ) ) )2 o tt 29 o

17 ·0 1 27 27 40

,

8 14 ' )

8

"

,

17 17 28 2'

7 9 12

l'

2 19 4 21 12 40 17 19 4 11 16 43 6

•

22 7 9 25 12 18

,

6 4.

CHI 4-12

2~

"~9 0-10 6-18 2-12 11-21 1!l~9

,-1) 11~1

2--4· 0-4 !)0.21 8-18

11~1 1 !}.o)1

'0.11

1~

10-20

-,

_4-14

_6 1-3 0-12 2--4 0-12 6-16 10-36 11-30 0-19 24'-)6 16-38 ()o.t4 1'~1 14~.

'-17 0-6 0-12 0-19 0-12 0-8 1-9 '~!I.

0-6 . 0·12 2-14 22""" 7~' 0-1' 3-11 )-7 6~6

8-12 N1 1-1, )-17 20.12 Eo-to ,-t) 7-1' 8-14 ,.."

2 ...

a-Hi

,~) 1t~9

2-4 0-;10 1)~1

1!}.o39 32""'0 ()a.6 1()o.t4 17·)1 1-3

2~

26-)8 0-6 _4 17--41

0-4

~ 0-8

0-'

14 .... 0 20·'.

3'-47 2008 0-;10 9-t!l 0 ...

0-19 0-11 3-1 N' 1'-19 20-'6 17-3)

2-16

~ ,,~O

_2 H 0-8 1-31

~9 .1~

27"",' 7~7

0-10 16-e&

11~

)0""'6 844 1-11 _6 12-)2 4040 ,0.1) 17-3' 8-16 10-;16

'·1 '-7

2 ...

1.2.3.0

1:10.' 1.26.0

1.002 1.8., h2.9 1'0.1

1.,.2 1.0.&

1.0.7

1.0.2 1.0.1

1.0.4

1.0., 1.0.t 1.0.2 110.2 1.0.1.

hO.7 1:0.2 1.0.0 1.0.8 1:1.,.

1.'.0 ,.0.4

"'4.0

,.0.9 hO.4

1.2.9

1.1 ••

h1.7

1.1.1

1.0.'

1.0.,

taO.6 1:0.6 hO.6

/PREDATION BY IM'UHlCliD AND NATIClD GASTROPODS 253

consequently, no sorting in practice), the probability d. finding the rl~ht and the left VIIllw is identical The proneness to the attack by boring gastropods Is cha- racterized through the percentage af the indivi1fuals attacked whiC'h oocur in the II'8llXPle under study. Since,. however, the dilferences in the size of samples of partlcu1a1" s.pecies are COIIlsi1feralble and the samples themselves Ifairly smaLl

in

^some

cases, the relatiOO6 in -actual populatdons were described by means of confidence inter:vals. They were compufled on the tbasis of a bLnomial 'PTobability distribution, since it is the simplest method of statistioal analysis of the "edtha- - or" type of data, viz. :in th'is case: "an attacked individUal - ' a non-aftacked Jndividual". Ilf the canfidence level is determined - .as 1IlS'UII11'ly in b:loII,ogicalI. studies ~ at 95 per cent, the confidence interval

may

be computed of!rom the following ifonnula (Reyment 19'7-1):

p±l96'" /p(l-P)

. V

^N

where p denotes the pet"ceatage of QIle of the duIes (iD tbls case: "the attacked individuals',)

in.tbe Ample, and N - the Bize of the sample.

FQ1" particular species, the autbons sought to determine the numerical ratio of the mdivlidua.1s attacked by the lIlaticids and the mucicids (naticid 'to'murldd prey 1"atio), hut due to the- difficulties mentioned above coo.cemiDg the identilfication of bordngs and the size of the confidence interval, this value was given only ;in the cases in which the num.ber of thelndMduals attacked was sulfficiently high 1;.0 assure an appropriate aoouracy.

The values given in Table 1 enable the, determination of a mean value for the main area of the Korytnica clay~ of the proneness of particular species to the attack, since the assemblage under study was collected at various exposures and stratigraphical levels of these clays.

If, however, the samples examined come from defiliite localities, the' deviation from the mean value may he considerable. As an example, the locality from which comes a sample markedly enriched in the ilaticids (locality I of littoral facies in RadwaflSki 1969, Fig. 31), but considerably impoverished in the species (Dr. W. Baluk's oral communication), is cha-

racterized by the percenta'ge of the attacked individuals of Nassa schoenni (R. Hoernes & Auillliger) distinctly higher (Table 2) than in 1!he ,main area of the Korytnica clays (cf. Tahle 1). A similar difference takes place for Natica pseudoredempta Friedberg, found only in this locality, when compared with mean values for the other species' of this genus (cf.

Tables 2 and 1).

As follows from a perfunctory analysis of the obtained data (cf·

Tahle 1), the proneness to the atta'Clk Iby boring gastrqpods is subject to consM.arabie fluctuations within one superfainily (e.g. Cardiacea), fartrlly (e.g. Bul1J.idae) and even genus (e.g. Actaeon, Alvania, Sveltia), which probably may !be explained by the occupation by particular species of sowewhat different ecological niches or by their special adaptations. In this respect, a fairly good example is offered by Cardiacea of various age (cf. Table 3) some species of which may quickly jump by means of their foot and thus escape the attackers (Davitashvili & Merklin 1966).

254 ANl'ONI BOI'FMAN, AlNDBZEJ', P.JBEB.A " JlA.BCJjN B'YBZKIEWICZ

Table 2

PrcnelleSB of local popuIla.tlons to :the attadk !by predatory bormg gastropods in the Lower Tortonian 0If ~ory1m.iea (ilocallty I, cf. the text)

.... be1' 01 ^~1' oent

~IO;:on

-

-"o18a · C ° = - oo:afU.DO&

, Allqlla, , attaolal4 1Dtenal , .peo:Weu

. . . o~BII1 /f,.

".1'M.

^& D1lI&HI 120 ⁾² 2.4-40

.a~~oa~ •• u4o~4e.,ta ~184be1' • • • ,. 8i 18 iD.,.:!'"

Table 3

Poroneness of Car&acea to the attaok by predatory boring gastropods .in v>ardous geo-

~ epochs

hr oellt'

Sped ... v.r°rort1011 9!"

o the oo:af1uDOe attaoke4 1Dtlnal apeo:lmeIlB

.1

Lutet:1&ll. 'ara Baa1D Aua4 ,oa 2qlO1', 1979/

Losooar41lul boue1 /De . . . . /

· . ^....

^{8 4-12}

Tltller1oll1'll1a lIIIb1'1oata DeIl2!&1ell • • '. • • 0 0,.,2 Telllll~ "1'1')11&ta ,DeBha.Tes • •

.. ..

^{3D 2&-32}

Bc 100 ... 1' 1!ortoll1aD, IH7tD1oa /21.. ~able 1/

caronta 'ONII" eo1'01'OUl& _e1'

· ..

^,.

. _l'

^8-0!2

CIU'd11111 ]Oap11lo.ua Pol1 • •

· . · ....

^{2 0-4}

Cl lleo8Jd:, ."..1' Delta Aua4 OD BU'll8Dt, 1971/

CIU'd1U11 kobelt1 T. llaltllall

· ^{· ·} . ...

^{10 10}

C&1'411III 1.aoUDOea lIeeve

. . _{· ·}

^'

. . ..

^{, 14 14}

CII1'Il11111 PQ»111oaum.Pol1 .•.• ,.

· . .

^'

. .

^,

.

^{26 26}

Table 4

Prmeness of mdlluSlk classes ^at' &roUP; to Ibhe· 81'tJtaJck Iby predatory bor:Ing gasbropods tin the Lowet' 'l'artooian of KOrytriica

__ '-1' 01 'er oeat Clau 01' 81'oup eC°^1lDeDB

proportion

"'

· the ' 01 the' . o o:af1ullu

.• ~le attaolal4. 1IIte~1

. BpeO:lmeU

GUt1'Opocla /total/

....

^{1727) 11 11}

1DOl.II41.IIsI .a1'1014e 681

,

3-1 Ilat1014a iOn 11

""'"

~le07Jlocla

... .. . . .

^{~44 11 10-12}

SoQhopocla

... . . . .

^{1216 4 ,~}

IPIREDATION.BY MUm:cID AND iNA'mCm GASTROPODS

As follows from the compa.rison <>f the ha'bitat and mode of life of Muricacea and Naticacea,. they could n'Ot meet each other and, conse- quently, nearly all borings found in their shells (PI. 1, Figs 3-4; PI. 2, Figs 3, 4) should ,be cOll!Sidere:d as symptoms of cannibalism (although it is obviously impossible to ascertain whether or not it is an intraspecific·

cannibalism). Only small n'UJm:OOr of Iborings may possibly oome from the naticids, which incidentally have· bored already empty shells buried.

in the bottom deposit. The percentage of attacked naticids in a population is exactly equal to the values computed for gastropods and pelecypodS akeady 1r!,!ated aos entire classes (Table 4). This indicates that the object of attaCk: was selected by the naticids rather at random and without any preference. The level of canniibalism among the muricids is markedly lower thana mean value of the proneness to attack computed for all

. .

^.

gastropods (Table 4), Which !Suggests that the muricids distinguished·

themselves when looking for prey. Such a suggestion is, as a matter of fac::f;, confirmed by laboratory studies (Wells 1958) showing that MureX' fulvescens Sdwerby recognizes

and

it .almost does not attack at all Ostrea.

equestris, a pelecypod most '~mon in its natural environment, and its main food consists of Crass08trea.

As seen from previous stUdies (Wells 1958, Poaine 1003, Taylor 1970), the mam food of the muricids 1l5'UiaJ.ly consists of a feweoID.mQ'Il species, pnimarlily 0If ,oysters and Cardiacea. However, :in the iKOil"ytnica clays, 'it is difficult to distinguish any grOlllp ·as a fundamental food. fOil" Muricacea, WhiCB pro.ball:)ly results from· the scantiness 0If oysters a;nd Carddacea with ,a simultaneous abundance of other pele- cypods and gastropods.

The percentage of the attacked. indiViduals in the Korytnica mol- lusks may sometimes exceed even 40°/6 (Table 1), as e.g. in Meretrix sp:

div., Pyrgulina interstincta (Montagu), Giycimeris pilosa deshayesi (Mayer), Tornatina truncatula (Bruguiere), in both the listed pelecypods being confined mostly to yOUlIlg individuals. The predatory 'boring gastropods might, therefore, pose a serious biological danger to some species and it is not unlikely that sometimes they might also become the main cause of the extinction of their local popuJations (cf. Fischer 1966).

In all proba'bility, the formation CIf the "conchioline" ~d-layer in the valves of Corbula might, therefore, play the role of a defensive mecha- nism. The efficiency 'Of such· a mechanism may be shown by the fact that, in the Recent popu1ations of Corbula, less than one per cent of the individuals fall a victim to the boring gastropods, although they attack them n'Ot less violently than in ·the g·eological past (Fischer 1963). It is also the thickness of the shell of Me.retrix, which causes that only less than a half 'df the individuals attacked perishes, th~t· may serve, among other functions, as a defence against the boring gastr'OPods. .

256 ANTONI HOFFMAN, AINDRZEJ' PISlCBA 8. YABClN RYBZKIEWlCZ

Several mollIuSks which iIn practice aTe not attacked 'by the pre- datory 'bOring gastropods at aU (cf. Table 1) have· also been found in the Kory'tnica clays. To a considerable extent, as in e.g. Semicassis miolae'V·i-

g~! Sacoo, FiCU3 Bp. div., Ra.n.ella '1OOTginata (Martin),

as

well as in Ancilla glandif07'mis (Lamarck), Clavatula aspeTulata. (Lamarck) and

. C. laevigata (EiC'hwald) this probably results·from the size of specimens

availabloe to the authors ^1, since the correlation between the proneness to the attack and. the size of a specimen is very distinct (cf. Table 5). The lat"ger the prey the larger was obviously the attacker (Reyment 1971) and it Mould be rememlbered that the number of large ptedators among the

.. umber or

G~ .peO;iMDB

111 tbII·

~l •.

G1'8ate.t aaat1'Opo4. )!140 8_11 ... t ..-t1'OJI04.e ~».

1'.1' a.llt p1'opo1't1QII

,or ^tbll'

attaolle4 epeo1aeDB

1,.

~

" . OODr14eD . .

1IIt.1"t'al

4-6

",,.-16

Table 5

R6la1liooehip between proneneu to the attack by preda-tory !boring .ga- strapods and size of the prey inlthe

~ ToIItonian of Korytni~a

Korytnica gastropods is strongly limited (cf. Friedberg 1911-1928, 1938).

Not all of course may be explained by the interdependence between the proneness to the attack and the size of potential prey, as among the almost not attacked . Korytnica species there are also small ones (cf. Table 1), such' as e.g. Cardium papiUosum Poli, Hyala vitTea (Montagu), Peratotoma unica (Boettger), Ringicula auriculata. buccinea (Brocchi) and Teinostoma Woodi (Hoernes). Their security might have most likely resulted from a small probabiility Of meeting predatory 'boring g8lStropOds, the feature caused by their· settlement in different ecological niches. As shown by the example of the genus Ringicula, which was not attacked as early as in the Lutetian of the Paris Basin (Taylor 1970), such a situation may peI'Bist fairly long, but, on the other hand, the fact that the species almost not attacked ad: a!l.l at Korytnica, that is, Co:rdium papillosum Poli, makes up at present a main food of the natidds in the Niger Delta (Reyment 1966a, b), indicates a possibility of fundamental changes.

As shown by the tabularized data on the numerical ratio of the naticid and muricid prey among large taxonomic groups (Table 6), the

i~terests of the two groups of the predators strongly differ fu'om each other: the naticids mostly attack ^~ecypodS and scap'hopods, as well as some of the gastropods, while the muricidLs are primarily interested. in ga'Stropods. Thus, the former confine -themselves in principle to the i~fauna

and the latter ,to the epifauna. Noteworthy ds, however, the fact that the

1 Mostly adult specimms hB'voe been collected in the soil of arable fields at Korytnlca.

IPBEDATIONBY !MUHICllD. AND NAT:lClD GASTRpPODS

257

Korytnica clays also contain molluSks, e.g. Anadara dilu'Vii (Lamarck), which make up the object of competition of predatory boring gastropods

elu. ^•• Uo14 to .no14

»~T :ra"o

Table 6 aut::ropo4a 111.1

Nat1cld to mudald prey ratio IIn partf,cular mollusk

&sses in the Lower TorflOllian <if KQl"ytnica

h1801»o4&

Soaphopo4a

110.&

110.6

(cf. Table 1). This fact results fram their mode of life transitional between the epi- and infaul1A.

The soundness of the suggestion con-cerning different interests of the' naticids 'and muricids is confirmed by the results presented in Table 7:

smaH. (less than 3 mm); ribbed gastropods are mostly attaclred by the muricids and smooth ones primarily by the naticids. It is obvious when considering that the smoothness of the shell of small gastropods isa feature important to the adaptation to the life in sediment, while the sculpture - to the Hfe on the surface.

T·aba.e 7

Naticid to mtn'idd pt'eyrarl;io in ·gasbro-·

pods of various shell ornamentation; L0-

wer T011ton1an !Otf Klrybnica

G:roUll

r - -

s.u :ribbed patro»o4a.

SGa11 -.oo~ ... t:rppp~

B.t101d·to mur1014 Pft7 :ratio

1i1.7 , :0 .••.

~ontrary to Ziegelmeier's.(1954) and Boekschoten's (1966) sug- gestions; no interdependence between .the degree' of ornamentation 6f a shell and the percentage of the individuals attacked by all the predatory boring gastropods has ever been found 'among the Korytnica mollusks (Table 8). This is the reason why precisely such a justification of ,the -character of the strong. differentiation of the proneness of the. Upper Cretaceous and Paleocene 'ostracods from Nigeria to the attack (Reyment

Table 8

Relationship betw-een the degrtje of shen omamenta1don of th-e iprey and P!'0IleJle(SS

to ctbe attaclt by predatory boring gasbro·

pods in the Lower T«tonian of Korytnioo

~OQ

li1b1M4. pat:ropodB

BIIoo~ patropo6a

Per oellt

~rmoll OOD:t14ll1U18

-

^. . attaolald' 1nte:rY&l ltJIeo:lMDa

l'

^14-16.

1"

")""7

1963, 1966'a) seems' to the authors to 'be insufficient. One could rather suPPose that a decisive role herein was probably played by the ecology of potential prey and not by the resistance of their more or less sculptured carapaees to the attack by the boring gastropods.

17

26:8 ANTONI BOFFM~ •. ANDBZEJ PJlSERA & MABC.I:N .BYSZ'KIEWK:z

Interesting :l$ the eampadson 0If muri;cid 'lUld nati:ei-d predatiriil: aC'bivities in dJfiferent geoloiical epocbs. There ,is a 10 timces gr~at~n~r (baosed on Taylor 11110) of prey for each muricid spectroen than for naticid one, in the Luteflian or the !Paris Basin. iIn tthe !Lower Tortonian Korytnica clays this proportion is even IUgber: a num'ber af prey is !for each mUll'icid specimen 20 flimes greater than for nBticld one. This growth .otf muricid acti'Vity may be regarded as being related to the enlarging of their body size, ^IQ feature IJo characteristic dn the evoluticm Of iMu- rieacea si:iice the Eooene through the U~per Pliocene (cf. Fischer 192'a).

CONCLusrONS

Analysis of the traces Cif the predation 'by the Muricacea. and the Naticacea found· in' the assemblage of the Lower. Tortonian mollusks at

Korytni~ allows one to state ,that at least since. that geological epoch and, as shown by the comparison with the data from the Paris Basin presented by Taylor (1970), even since the Lutetianthe ecology and ethology of these' groups have not been the subject to 'any fundamental changes.

Despite a similar manner of securing their food the competition between the two groups is rather smaU and limited only to a narrow transitional zone, which facilitates the coexistence of great populations of the muric- ids and naticids. On the Other hand, this division of interes1ls of the :muricids and naticids causes that· ·the numerical ratio of their prey in a popWlation may Ibe of importance to the determination of the . ecology of the species 'being the prey.

The great size of the samples studied precludes with a considerable degree of reliability any chance character of the results obtained. and subsequently used as a 'basis for ecological and paleontological conside- rations, although it is true that smaLl samples require the application for this purpose at least the simplest statistical analysis. One may suppose that the cOlll/Puta.1fion of the confidence intervals, used in the present paper, asSures a sufficient jlUsti!fication of ecological conclusions. Lt also seems. that this may considerably facilitate any po8Siible comparisons of the data from Korytnica with those coming from other areas and other geelogical epocbs. . '

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WarBflW, Jwe 1973

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Warszawa.

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:Pit ..

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