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(continued inside back cover)

ANNALS OF THE SOUTH AFRICAN MUSEUM

ANNALE VAN DIE SUID-AFRIKAANSE MUSEUM

Volume 89 Band

June 1982 Junie

Part 4 Deel

INTERPRETATION OF TENTACULAR CLUB

STRUCTURE IN

STHENOTEUTHIS OUALANIENSIS (LESSON, 1830)

AND OMMASTREPHES BARTRAMII

(LESUEUR, 1821)

(CEPHALOPODA, OMMASTREPHIDAE)

MARTINA A. ROELEVELD

Cape Town Kaapstad

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INTERPRETATION OF TENTACULAR CLUB STRUCTURE IN

STHENOTEUTHIS OUALANIENSIS (LESSON, 1830)

AND OMMASTREPHES BARTRAMII (LESUEUR, 1821)

(CEPHALOPODA, OMMASTREPHIDAE)

MARTINA A. ROELEVELD

South African Museum, Cape Town

(With 6 figures)

[MS accepted 25 February 1982]

ABSTRACT

The club structure in the family Ommastrephidae is shown to be more easily interpreted if

the first dactyl row is taken to be that row in which the ventrolateral sucker is equal to, or

larger than, the ventromedial and the carpus is considered to be restricted to the region bearing

biserial suckers. All the proximal suckers that may be considered to be quadriserially arranged

are taken to pertain to the manus, even when subequal in size.

Using these definitions, the club structure in ommastrephids is found to be remarkably

uniform. In the subfamily Ommastrephinae the position of the fixing apparatus is found to be

constant within a species if it is defined by the position of the first smooth ringed sucker; its

position in Ommastrephes bartramii is clearly different to that in Sthenoteuthis oualaniensis and

other species.

It is shown that the sucker arrangement of the clubs may be related to their function of

capturing prey.

CONTENTS

PAGE

METER AUCTION er eee ee ee ee a eee eee ese inte 249

ISTONICAlITE VIE Werner AS eto ees 250

Proposed interpretation of club structure............. 253

DISCUSSION MES eek eet eee ie ken Be ich eee a DEE Peed tools 261

Acknowled cements) mertyaccuseci ui aehin examen eae 263

References y, tet ie Ate eee ee cheer een ps ee 263

INTRODUCTION

Squids (order Teuthoidea) are primarily active predators feeding mainly on

fish, crustaceans, and other squids. Prey is captured and held by the circumoral

appendages, which consist of eight sessile arms and two tentacles. The sessile

arms usually bear suckers or hooks over most of their length and are used to

hold the prey while it is being eaten. The function of the tentacles is to capture

the prey and bring it within reach of the arms. The tentacles differ from the

arms in that they usually have a bare stalk that is very extensible, the length of

the tentacle depending on the degree of contraction of the longitudinal muscles.

The distal end of the tentacle is expanded to form a club that bears toothed

suckers or hooks.

249

Ann. S. Afr. Mus. 89 (4), 1982: 249-264, 6 figs.

250 ANNALS OF THE SOUTH AFRICAN MUSEUM

Young & Roper (1968: 197-202) have given a comparative evaluation of

the familial characters in the suborder Oegopsida, which includes twenty-three

of the twenty-five families of squids. They have pointed out that the structure

of the tentacular club is one of the more stable characters used in classification

at the familial level and that an understanding of club structure and variation

throughout the suborder is essential for the establishment of a coherent

classification. Furthermore, the club is not only of primary importance in

defining families but is often diagnostic at the generic and specific levels as well.

The above authors cite the Ommastrephidae (except ///ex) as one of the groups

possessing the basic or typical club, which occupies a relatively small portion of

the tentacle, is at least somewhat expanded and flattened, and is divisible into

three distinct areas: the carpus, the expanded manus possessing marginal

trabeculate membranes and four rows of suckers, and the narrow dactylus

where the suckers become greatly reduced in size (the dactylus also has four

rows of suckers in all the ommastrephids except ///ex, which has eight rows of

suckers on the dactylus). In addition, the typical club usually exhibits a more or

less distinct pattern of small suckers and knobs that, when held together, form

a locking device, the carpal structure or fixing apparatus.

The basic structure of the ommastrephid club, as outlined above, has long

been recognized. ‘The precise definitions of the three regions and of a trans-

verse row are less clearly agreed upon, however, and have varied from author

to author or have been ignored.

HISTORICAL REVIEW

One of the earliest descriptions of ommastrephid club structure was given

by Pfeffer (1912: 374-376), who suggested that the carpus, manus, and dactylus

may only be delineated by careful analysis, and pointed out that the suckers of

the three regions differ in size and dentition.

Pfeffer found that the suckers on the dactylus are significantly smaller than

the rachial (median) suckers of the manus and that in each transverse dactyl

row the two ventral suckers are generally larger than the two dorsal ones. This

relationship becomes unclear only near the tip of the club and proximally, in

transition to the manus region: in the second dactyl row the two ventral suckers are

about equal in size but in the first (most proximal) dactyl row the ventral rachial

sucker is always larger than the ventral lateral sucker. The dactylus may then be

delineated from the manus by the difference in size between the most distal rachial

sucker of the manus and the most proximal one of the dactylus, this size difference

being much more noticeable on the right club than on the left, since both clubs

have an asymmetrical structure. The dactylus may also be separated from the

manus by the dentition of the rachial suckers; the lateral manus suckers and the

more proximal dactylus suckers resemble the more distal suckers of the arms,

whereas the rachial suckers of the manus have a unique form of dentition (i.e.

completely different to the dentition of any other sucker of the species).

TENTACULAR CLUB STRUCTURE, OMMASTREPHIDAE Dail

Regarding the sizes of the carpal suckers, Pfeffer noted only that the

rachial sucker is clearly larger than the lateral sucker in the distal carpal rows,

but not more proximally. The dentition of the carpal suckers generally resem-

bles that of the large arm suckers.

Pfeffer considered an analysis of club structure to be important. because he

believed that individual species could be distinguished by the number of

quadriserial rows, particularly of the carpus and manus. Pfeffer’s concept of a

transverse row was as follows: in each quadriserial row the lateral sucker is

proximal to the rachial and the dorsal rachial sucker is somewhat proximal to

the ventral rachial sucker. This suggests that Pfeffer interpreted an imaginary

line passing through the centres of the suckers of one transverse row as

forming an arc across the oral surface of the club, rather than an oblique, more

or less straight line. Pfeffer also saw all the club suckers of ommastrephids

(except J/lex) as quadriserially arranged, including those of the carpus, though

he noted that on the left club the most proximal sucker is missing, so that the

proximal quadriserial row of the carpus of the right tentacle corresponds to a

triserial group on the left tentacle.

Pfeffer considered that the ommastrephid fixing apparatus, consisting of a

dorsal lateral row of alternating knobs and suckers, belongs primarily to the

carpus, though continuing on to the manus in many species. He noted that the

number of elements of the fixing apparatus varies but that its position is more

constant and may be determined by counting the number of suckers proximal

to the first (most proximal) knob.

Pfeffer’s careful description of ommastrephid club structure is largely valid

but his method of club analysis proved very difficult in practice, as he himself

pointed out. Whilst delineation of the manus from the dactylus is satisfactory

provided that the differences in size and dentition are clear, he relied entirely

on dentition to distinguish carpal from manal suckers. But transitional condi-

tions occur, and the dentition of the median (rachial) suckers gradually changes

from the carpal to the unique median manus condition and from the latter to

the dactyl condition, though the transition from manus to dactylus is more

rapid (over about two to three transverse rows) than from carpus to manus.

Similarly, the transition in sucker size from manus to dactylus is not always as

distinct as indicated by Pfeffer; the transition in sucker size from carpus to

manus is very gradual and does not permit the delineation of the two regions by

the criterion of relative sucker size.

Pfeffer has pointed out another disadvantage of using sucker dentition

to delineate the regions of the club, namely the fact that sucker dentition is

only rarely visible in situ, so that an investigation of dentition necessitates

the dissection of a large number of suckers from several specimens.

Clearly determination of the limits of the three club regions and of the

number of transverse rows in each region using only the criteria of relative

sucker size and arrangement, independent of dentition, would be a distinct

advantage.

252, ANNALS OF THE SOUTH AFRICAN MUSEUM

Pfeffer, using his concept of the transverse row as outlined above, sug-

gested that the number of rows of the manus and carpus may be determined,

after the distal limit of the manus has been established, by tracing the rows, one

by one, from the clearly quadriserial rows of the manus and proceeding

proximally. This is not, however, always possible as the suckers may become

displaced due to distortion. Pfeffer suggested that in these cases the total

number of suckers on the manus plus carpus be counted and divided by four!

Another difficulty in analysing the quadriserial rows of the carpus is due to the

progressively wider separation of the more proximal suckers, so that they

appear to have an irregular or scattered arrangement.

The different interpretations of ommastrephid club structure by various

subsequent authors may best be illustrated by citing some of their descriptions,

with particular reference to the carpal region where the main disparities arise.

Since these authors described different species, it is necessary to point out that,

according to the interpretation of the present author, the species under discus-

sion all have the same basic sucker arrangement but that the fixing apparatus

varies as follows: in the subfamily Todarodinae the fixing apparatus is repre-

sented by a series of knobs, which may be clearly or poorly defined, alternating

with toothed suckers; in the subfamily Ommastrephinae (except in Ornithoteu-

this spp.) the fixing apparatus consists of a variable number of alternating knobs

and smooth ringed suckers situated along the dorsal edge of the club in the

proximal region.

Berry (1918: 236-237) described the club of Nototodarus gouldi (McCoy)

(Todarodinae) as bearing suckers in four rows, the eight large pairs of median

manus suckers succeeded by three pairs of evenly diminishing suckers that, with

the marginal series, passed imperceptibly into two rows of very small suckers

(some four to six pairs) on the carpus. He saw the carpal suckers as tending to

occur in alternating but only slightly differentiated sizes, the larger evidently a

continuation of the two central rows of the club, the smaller of the marginal

rows. The fixing apparatus was sometimes so obscure as to be practically

indistinguishable, but where best preserved it found its proximal beginning

after the third sucker of the dorsomarginal row and comprised first a small pad,

then three large ones in regular alternation with the suckers of this row on the

basal portion of the club.

Sasaki (1929), in his monograph on the Cephalopoda of Japanese and

adjacent waters, described six species of the Ommastrephidae. He recognized

that the most proximal suckers of the carpus could not readily be considered as

forming transverse rows of four but did not offer a single alternative interpreta-

tion. Thus for Ommastrephes sloani pacificus (= Todarodes pacificus Steen-

strup) (Todarodinae) he described the eight to eleven carpal suckers as small

nearly uniform suckers arranged in three or four rows of 1, 3, 4 or 2, 3, 4 or

3, 4, 4 or 1, 2, 3, 4 in each (Sasaki 1929: 279). In his figure (text-fig. 134B) he

illustrated the 2, 3, 4 interpretation.

Adam (1952: 108-109) stated that at the base of the club of Ommastrephes

TENTACULAR CLUB STRUCTURE, OMMASTREPHIDAE 253

pteropus [= Sthenoteuthis pteropus* (Steenstrup)] (Ommastrephinae), on the

dorsal side, there were three to five rounded papillae alternating with as many

small suckers that had smooth horny rings. Proximal to the first papilla there

were none to two small suckers, also with smooth rings. At the base of the club

the suckers were at first placed in pairs, then in rows of four, followed by the

rows of four suckers of the principal part of the club (the manus). Adam found

it impossible to establish clear limits for the three groups of tentacular suckers,

which comprised two to four rows of four carpal suckers, eight to ten principal

and twenty to thirty distal rows.

Voss (1963: 131-132) described the club of Nototodarus sloani philippinen-

sis Voss (Todarodinae) as occupying about three-fourths of the total tentacle

length. The indistinct carpal section bore about eleven suckers, differentiated

by their dentition, that might compose the carpal cluster. Five of these were not

in regular order but consisted of a proximal pair, followed by three others in an

irregular row. Beyond these the next four were also irregular. The suckers of

the manus were in four rows.

Young (1972: 29-30), in describing the club of Ommastrephes bartramii

(Ommastrephinae), saw the suckers proximal to the manus as irregularly

aligned and extending on to the tentacular stalk for a short distance. He

described the fixing apparatus as consisting of two to four smooth-ringed carpal

suckers alternating with two to four pads, lying at the proximal end of the

manus along the ventral margin (clearly a /apsus calami for dorsal margin).

Proximal to the fixing apparatus there were five to six toothed suckers.

Wormuth (1976), in his revision of the Pacific ommastrephids, saw the club

suckers as arranged in longitudinal columns rather than in transverse rows. He

described (p. 26) the club of Symplectoteuthis oualaniensis (= Sthenoteuthis

oualaniensis) (Ommastrephinae) as having a carpal region with a differentiated

fixing apparatus consisting of three to five knobs alternating with suckers having

smooth rings on the dorsal oral surface of the club; the fixing apparatus started

basally with a smooth ringed sucker and usually ended distally with a knob. There

were three small, slightly dentate suckers on the ventral oral surface of the carpus.

PROPOSED INTERPRETATION OF CLUB STRUCTURE

In the course of examining over 130 specimens of Sthenoteuthis oualaniensis

and numerous others of the remaining ommastrephid species with a view to a

systematic revision of the family, it has been found that the arrangement of

suckers and knobs on the tentacular clubs is far more regular than indicated by

the above descriptions by previous authors, and that club structure may readily

be compared from species to species if the basic ground-plan of sucker

arrangement is recognized.

* Ommastrephes pteropus and Symplectoteuthis oualaniensis were united in the genus Sthe-

noteuthis by Zuev et al. (1975: 1475). Symplectoteuthis Pfeffer, 1900 (type species Loligo

oualaniensis Lesson, 1830), thus becomes a junior synonym of Sthenoteuthis Verrill, 1880 (type

species Architeuthis megaptera Verrill, 1878 = Ommatostrephes pteropus Steenstrup, 1855).

254 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 1. Semidiagrammatic representation of the tentacular clubs of

Sthenoteuthis oualaniensis, mature male, mantle length 126 mm,

Galathea sta. 420, 10°24'N 126°40’E. C,, C-—first and second rows

of carpus, d—dorsal, D,—first row of dactylus, k—knob of fixing

apparatus, M,, M.—first and second rows of manus, OS—odd

(unpaired) suckers of carpus, ss—smooth ringed suckers of fixing

apparatus, v—ventral.

TENTACULAR CLUB STRUCTURE, OMMASTREPHIDAE UES

Fig. 2. Semidiagrammatic representation of the tentacular clubs of

Ommastrephes bartramii, SAM-S241, immature male, mantle length

182 mm, Meiring Naude sta. SM 171J, 33°20,0’S 28°12,7'E. Abbreviations

as for Figure 1.

256 ANNALS OF THE SOUTH AFRICAN MUSEUM

In S. oualaniensis (Fig. 1), for example, most of the club is taken up by the

manus where the median suckers are much larger than the lateral ones, though

the median suckers gradually reduce in size distally and proximally. On the

dactylus, on the other hand, the sucker size reduces gradually from proximal to

distal (except at the extreme tip where the suckers are subequal in size) and

also from ventral to dorsal, i.e. the ventrolateral, ventromedial, dorsomedial,

and dorsolateral suckers of one transverse row is each a little smaller than the

last. As pointed out by Pfeffer (1912: 374) there is often a distinct difference in

size between the median suckers of the manus and those of the dactylus, but in

many cases this size difference is not so clear and it is difficult to determine the

border between the two regions. It has, therefore, been found convenient to

define the first dactyl row as that row in which the ventral lateral sucker is equal

to, or larger in size than, the ventral median sucker.

In well-preserved specimens the suckers of the dactylus may easily be seen

as being arranged in oblique transverse rows in which the dorsolateral, dorso-

medial, ventromedial, and ventrolateral sucker is each situated a little more

distally than the last, i.e. an imaginary line through the centres of the suckers

forms an oblique, more or less straight line across the oral face of the club, with

the dorsal end of the line being more proximal than the ventral end (Fig. 1).

This arrangement continues almost to the distal tip of the club where the last

one or two transverse rows may have only two or three suckers in each.

This interpretation of a transverse row may also be applied to the suckers

of the manus and may be traced proximally even to the region where the

suckers become more subequal in size. Ultimately, however, there remain a

few proximal suckers that appear to have a general biserial rather than

quadriserial arrangement and their number is remarkably constant, being five

suckers on the right club and four on the left. These may be interpreted as

constituting two pairs plus one odd (distal) sucker on the right club and one

pair plus two odd (one proximal and one distal) suckers on the left, if the

orientation of the biserial rows is to be the same as that of the quadriserial

rOWS.

The distinction of the proximal group of biserial suckers from the quadri-

serial suckers is particularly clear in well-preserved specimens of moderate size

(e.g. Fig. 3D); in very large specimens (and also in smaller specimens in a

flaccid condition) the carpal region is frequently stretched, resulting in the

irregular or scattered condition mentioned by Pfeffer (1912: 374). It has been

found convenient to consider the biserial suckers as carpals and the quadriserial

suckers, even when more or less subequal in size, as manus suckers. Though

the median suckers of the first manus row are, indeed, not much bigger than

the laterals, there is usually a discernible difference in size, which rapidly

increases distally, and the quadriserial arrangement of the first manus row can

always be traced by the position of the origin of the sucker stalks, even in cases

where the suckers have been displaced.

Despite the very different descriptions of the carpal region by the authors

TENTACULAR CLUB STRUCTURE, OMMASTREPHIDAE MSI}

Fig. 3. Semidiagrammatic representation of the carpal region of various ommastrephid tentacu-

lar clubs, superimposed by the present interpretation of sucker arrangement. A. Nototodarus

gouldi, left club of female, mantle length 218 mm (after Berry 1918). B. Sasaki’s interpretation,

and C. present interpretation of the right club of Todarodes pacificus, male, mantle length

255 mm (B and C after Sasaki 1929). D. Sthenoteuthis pteropus, right club of female, mantle

length 365 mm (after Adam 1952). E. Nototodarus sloani philippinensis, left club of female,

mantle length 180 mm (holotype) (after Voss 1963). F. Ommastrephes bartramii, left club of

male, mantle length 303 mm (after Young 1972). Abbreviations as for Figure 1; stars indicate

missing suckers.

258 ANNALS OF THE SOUTH AFRICAN MUSEUM

cited above, an examination of their illustrations (Fig. 3) shows agreement with

the basic ground-plan of sucker arrangement just described.

Berry’s (1918, pl. 66 (fig. 2)) figure of Nototodarus gouldi illustrates the

confusion that may arise when the proximal region of the club is stretched so

that the subequal suckers of the first few manus rows appear to be more or less

biserial. Nevertheless, their quadriserial origins may be traced (Fig. 3A),

leaving four truly biserial carpal suckers since this is a left club.

Sasaki (1929) offered several alternative interpretations for the grouping of

the proximal club suckers of Todarodes pacificus and illustrated the 2, 3, 4

interpretation (Fig. 3B). Of all his alternatives this is the closest to the present

interpretation (Fig. 3C) of 2, 2, 1, 4 for the right club, though the row of four is

here considered to pertain to the manus and not to the carpus.

Adam’s (1952, fig. 47C) illustration of the carpal region of Sthenoteuthis

pteropus shows the clear distinction between the biserial carpal and quadriserial

manus suckers (Fig. 3D) and fully agrees with the ground-plan outlined above,

whereas the club of Nototodarus sloani philippinensis, as illustrated in Voss

(1963, fig. 28C), seems to differ markedly. However, this specimen (the holo-

type) has been re-examined and was found to have lost two suckers in the

positions indicated in Figure 3E. Taking the missing suckers into consideration,

it may be seen that the sucker arrangement of N. sloani philippinensis agrees

with the above ground-plan, as does that of Ommastrephes bartramii (Fig. 3F)

as illustrated in Young (1972, pl. 7M). Wormuth (1976) did not give illustra-

tions of the tentacular clubs, but his description of the club of S. oualaniensis is

applicable to Figure 1.

The presence of five right and four left biserial carpal suckers has been

observed to predominate in all species of ommastrephids, with the exception

only of Hyaloteuthis pelagica (Bosc), which seems to have fewer carpals on the

right club. Very few specimens of H. pelagica have been examined thus far, but

in the four right clubs seen the number of carpal suckers varied from one to

three; the only left club examined had the usual four carpal suckers.

In the Ommastrephinae, the constant position of the fixing apparatus along

the dorsal proximal margin of the club becomes even more clear if the fixing

apparatus is considered as a unit consisting of alternating knobs and smooth

ringed suckers. It has been found that the first (most proximal) element of the

fixing apparatus may be either a knob or a smooth ringed sucker; most

commonly, the fixing apparatus begins with a sucker on the right club and with

a knob on the left club. It is, in fact, the position of the first smooth ringed

sucker, rather than that of the first knob, that is constant.

The smooth ringed suckers of the fixing apparatus are actually modified

carpal and/or lateral manus suckers and as such they also form part of the

regular sucker arrangement of the club. Thus in Sthenoteuthis oualaniensis the

first smooth ringed sucker of the fixing apparatus is also the first dorsal carpal

sucker (Fig. 1). As the number of suckers (and knobs) in the fixing apparatus

varies, this may also involve the modification of the more proximal dorsal

TENTACULAR CLUB STRUCTURE, OMMASTREPHIDAE Jessy

Fig. 4. Three possible variations of the fixing apparatus on the right

club of Sthenoteuthis oualaniensis. A. First element of fixing appara-

tus, a sucker; two suckers proximal to the first knob. B. First

element of fixing apparatus, a sucker; one sucker proximal to first

knob. C. First element of fixing apparatus, a knob; no suckers

proximal to first knob.

lateral suckers of the manus in specimens having a longer fixing apparatus, but

the fixing apparatus always begins with the carpals in this species.

The position of the first knob of the fixing apparatus may be either

proximal or distal to the first smooth ringed sucker (Fig. 4) and this has led to

confusion in the past. If the first knob is distal to the first smooth ringed sucker

(Fig. 4A-B), the number of suckers (regardless of type of dentition) proximal

to this knob will be one (Fig. 4B) or two (Fig. 4A), depending on the position

of the knob relative to the position of the ventral carpal suckers. If, however,

the first knob is proximal to the first smooth ringed sucker (Fig. 4C), there are

260 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 5. Aberrant carpal condition in the tentacular clubs of Sthenoteuthis pteropus (after Adam

1952). es—extra suckers, ?7k—knob presumably missing.

no suckers proximal to the knob. Thus past authors have stated that there are

none to two suckers proximal to the first knob in S. oualaniensis. But if the

position of the fixing apparatus is considered to be determined by the position

of the first smooth ringed sucker, and if only the suckers in the dorsal

longitudinal column are considered (the ventral carpals being ignored), then it

may be seen (Figs 1 and 4) that in §. oualaniensis there are no suckers proximal

to the first smooth ringed sucker in the dorsal column.

In the specimens examined, Sthenoteuthis pteropus and Dosidicus gigas

(d’Orbigny) have the same type of club as S. oualaniensis, i.e. with the fixing

apparatus beginning in the carpal region. There is, however, an aberrant

condition (Fig. 5) that occasionally occurs. In these cases there appears to be a

proliferation of the carpal suckers proximally and the regular arrangement is

disrupted. Such a condition has been described and illustrated for S. pteropus

by Adam (1952: 110, fig. 47F-G) and has been observed in several specimens

of S. oualaniensis (Roeleveld unpublished). In Adam’s specimen of S. pteropus

there are five extra suckers on the right club; the left club has seven extra

carpal suckers and also appears to lack at least one knob. The number of extra

carpal suckers varies considerably in these aberrant specimens, which are

otherwise indistinguishable from their conspecifics.

TENTACULAR CLUB STRUCTURE, OMMASTREPHIDAE 261

The club of Ommastrephes bartramii (Fig. 2) differs from that of S.

oualaniensis (Fig. 1) in that the fixing apparatus is somewhat more distally

placed. On the right club of O. bartramii the first smooth ringed sucker of the

fixing apparatus is also the dorsal lateral sucker of the first manus row; on the

left club the first smooth ringed sucker of the fixing apparatus pertains to the

second manus row. Thus on both left and right clubs of O. bartramii there are

two (toothed) suckers proximal to the fixing apparatus in the dorsal longitudi-

nal column; the smooth ringed suckers of the fixing apparatus are all modified

lateral manus suckers and the carpal suckers do not participate in the fixing

apparatus. In S. oualaniensis, on the other hand, the fixing apparatus always

begins with the carpus and the lateral manus suckers are involved only if the

fixing apparatus includes more than one (left club) or two (right club) smooth

ringed suckers. Put another way, if the dorsal longitudinal column of suckers

alone is considered, there are two dorsal suckers proximal to the fixing

apparatus in O. bartramii and none in S. oualaniensis.

The aberrant clubs occasionally found in S. oualaniensis and S. pteropus

cannot be confused with those of O. bartramii, as in the aberrant condition the

fixing apparatus usually begins in the carpal region, and the extra carpal suckers

have smooth rings. In O. bartramii the carpal suckers are not involved in the

fixing apparatus and have teeth on the distal part of the ring.

DISCUSSION

Since the primary function of the tentacular clubs is to capture active prey,

any particular arrangement of the suckers presumably has a functional advan-

tage. As the left and right clubs act together, the sucker arrangement of the two

clubs may be seen in relation to each other if the mirror image of one is

superimposed on the direct representation of the other (Fig. 6). When seen in

this mutual relationship, the sucker arrangements present a number of interest-

ing points. As first noted by Steenstrup (1857: 120) the knobs of the fixing

apparatus of one club lie opposite the smooth ringed suckers of the other.

Secondly, the carpal suckers not involved in the fixing apparatus, and hence

with toothed rings, lie opposite the spaces between the suckers of the opposing

club. Thirdly, the toothed suckers of the manus do not lie exactly opposite each

other but are staggered, so that it is less likely that a sucker of one club will

adhere to a sucker of the other club, as would happen if they were exactly

opposite each other. The firm grip of two exactly opposed toothed suckers

would presumably be difficult to release and would hamper the true function of

the clubs, which is to grasp prey.

On the basis of this mutual relationship of the opposing club suckers, a

reconstruction of the function of the ommastrephid clubs may be attempted.

When the tentacles are extended to seize prey they would presumably be joined

along the dorsal proximal edge of the clubs by the fixing apparatus, ensuring

that both tentacles are extended to the same length and reach the prey at the

262 ANNALS OF THE SOUTH AFRICAN MUSEUM

Fig. 6. Diagrammatic representation of sucker relationships in the proximal region when the

left and right clubs of Sthenoteuthis oualaniensis are placed face to face. Circles represent

suckers, crosses represent knobs; suckers and knobs of left club dotted, those of right club

entire.

same time. The prey may then be captured by a tong-like action of the joined

clubs, as has been recorded photographically (Baker 1957, fig. 3a).

Lane (1960: 38) has suggested that the united strength of the tentacles may

then be used to drag in the prey. This more efficient use would then presum-

ably enable the capture of larger or more active prey than if the tentacles were

less co-ordinated. Kristensen (1981 pers. comm.) does not agree with Lane’s

suggestion and believes that if the clubs were still joined together on retraction

it would hamper the regular contraction of the tentacular stalks.

Kristensen (1981 pers. comm.) has suggested that the fixing apparatus may

also be used to hold the clubs within the cone formed by the circumoral

appendages (arms plus tentacles) for streamlining while swimming.

The development of teeth on the horny rings of the suckers is considered

to be an advanced condition and would be a distinct advantage in fast

swimming squids feeding on active prey, since the teeth of the sucker rings

ensure a firm grasp as they dig into the tissues of the prey. With the develop-

ment of the fixing apparatus, however, a number of suckers are set aside to

grasp not the prey but the knobs on the opposing tentacle of the squid itself. It

would then be an advantage if the sucker rings were smooth and not toothed.

Thus the smooth ringed suckers of the fixing apparatus have undergone a

secondary loss of teeth, so that in the region where the clubs adhere to each

other the possibility of self-inflicted damage is eliminated. Further adhesion of

the clubs to each other is minimized by the staggered positions of the toothed

suckers. Once the prey has been captured, the fixing apparatuses of the clubs

may be rapidly separated by release of the vacuum in the sucker chambers.

TENTACULAR CLUB STRUCTURE, OMMASTREPHIDAE 263

ACKNOWLEDGEMENTS

This study is based upon material in the South African Museum and from

numerous other institutions whose personnel provided access to material and

facilities for study. I should like to thank G. L. Voss, Rosenstiel School of

Marine and Atmospheric Science, University of Miami; J. H. Wormuth,

Department of Oceanography, Texas A & M University; C. F. E. Roper and

M. J. Sweeney, Division of Mollusks, National Museum of Natural History,

Washington, D.C.; C. C. Lu, previously of the Department of Biology,

Memorial University of Newfoundland and now at the National Museum of

Victoria, Melbourne, Australia; M. R. Clarke, Laboratory of the Marine

Biological Association of the U.K., Plymouth; P. M. David, Institute of

Oceanographic Sciences, Wormley, U.K. and N. MacLeod, previously of that

institution; J. Knudsen, Zoological Museum, Copenhagen and T. K. Kristen-

sen, previously of that museum and now at the Danish Bilharziasis Laboratory,

Charlottenlund; P. Bouchet and F. Danrigal, Laboratory of Malacology,

National Museum of Natural History, Paris; J. M. Rosada and M. E. Cunha,

Department of Pollution and the Environment, National Institute of Fisheries

Investigation, Lisbon; W. Adam and J. van Goethem, Department of Recent

Invertebrates, Royal Institute of Natural Sciences of Belgium, Brussels; and F.

C. Naggs, Mollusca Section, British Museum (Natural History), London.

My sincere thanks go to M. A. Cluver and V. B. Whitehead of the South

African Museum and G. M. Branch of the University of Cape Town for

reading the manuscript and for their useful comments and criticisms. I should

also like to thank C. F. E. Roper of the National Museum of Natural History,

Washington, D.C., and T. K. Kristensen of the Danish Bilharziasis Laboratory,

Charlottenlund, for their comments on the manuscript.

REFERENCES

ApamM, W. 1952. Céphalopodes. Result. scient. Expéd. océanogr. belge Eaux cét. afr. Atlant.

Sud 3: 1-142.

Baker, A. DE C. 1957. Underwater photographs in the study of oceanic squid. Deep Sea Res. 4

(2): 126-129.

Berry, S. S. 1918. Report on the Cephalopoda obtained by the F.I.S. ‘Endeavour’ in the Great

Australian Bight and other southern Australian localities. Zool. (biol.) Results Fish. Exp.

‘Endeavour’ 4 (5): 201-298.

Lane, F. W. 1960. Kingdom of the octopus. The life history of the Cephalopoda. New York:

Sheridan House.

Lesson, R. P. 1830. Mollusques. In: Lesson, R. P. & Garnot, P. 1826-1830. Zoologie du

voyage autour du monde... sur... la Coquille pendant .. . 1822-25... Par M. L. I.

Duperry, etc. 2: 239-246. Paris.

Prerrer, G. 1900. Synopsis der oegopsiden Cephalopoden. Mitt. naturh. Mus. Hamb. 17 (2):

145-198.

PrerFER, G. 1912. Die Cephalopoden der Plankton-Expedition. Ergebn. Atlant. Ozean Plank-

tonexped. Humboldt-Stift. 2: 1-815.

Sasaki, M. 1929. A monograph of the dibranchiate cephalopods of the Japanese and adjacent

waters. J. Coll. Agric. Hokkaido imp. Univ. 20 (suppl.): 1-357.

STEENSTRUP, J. 1855. Kjaeber af en kolossal Blaeksprutte. Overs. K. dankse Vidensk. Selsk.

Forh. 1855: 199-200. In: Vousge, A., KNUDSEN, J. & Rees, W., trans. 1962. The

cephalopod papers of Japetus Steenstrup: 14-15. Copenhagen: Danish Science Press.

264 ANNALS OF THE SOUTH AFRICAN MUSEUM

STEENSTRUP, J. 1857. Hr. Professor Steenstrup foreviste og karakteriserede derpaa et Par nye

Cephalopoder. Vidensk. Meddr dansk naturh. Foren. 1856: 120. In: VoisgE, A., KNuD-

SEN, J. & Rees, W. trans. 1962. The cephalopod papers of Japetus Steenstrup: 16.

Copenhagen: Danish Science Press.

VERRILL, A. E. 1878. Notice of recent additions to the marine fauna of the eastern coast of

North America. Am. J. Sci. (3) 16: 207-215.

VERRILL, A. E. 1880. The cephalopods of the North-eastern Coast of America. Part I. The

gigantic squids (Architeuthis) and their allies; with observations on similar large species

from foreign localities. Trans. Conn. Acad. Arts Sci. 5: 177-257.

Voss, G. L. 1963. Cephalopods of the Philippine Islands. Bull. U.S. natn. Mus. 234: 1-180.

WormutTH, J. H. 1976. The biogeography and numerical taxonomy of the oegopsid squid family

Ommastrephidae in the Pacific Ocean. Bull. Scripps Instn Oceanogr. 23: 1-90.

YounG, R. E. 1972. The systematics and areal distribution of pelagic cephalopods from the seas

off southern California. Smithson. Contr. Zool. 97: 1-159.

Youna, R. E. & Roper, C. F. E. 1968. The Batoteuthidae, a new family of squid (Cephalo-

poda: Oegopsida) from Antarctic waters. Antarct. Res. Ser. 11: 185-202.

ZuEV, G. V., Nests, K. N. & NIGMATULLIN, CH. M. 1975. System and evolution of the squid

genera Ommastrephes and Symplectoteuthis (Cephalopoda, Ommastrephidae). Zool. Zh.

54: 1468-1479 (in Russian, with English abstract).

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6. SYSTEMATIC papers must conform to the Jnternational code of zoological nomenclature

(particularly Articles 22 and 51).

Names of new taxa, combinations, synonyms, etc., when used for the first time, must be

followed by the appropriate Latin (not English) abbreviation, e.g. gen. nov., sp. nov., comb.

nov., syn. nov., etc.

An author’s name when cited must follow the name of the taxon without intervening

punctuation and not be abbreviated; if the year is added, a comma must separate author’s

name and year. The author’s name (and date, if cited) must be placed in parentheses if a

species or subspecies is transferred from its original genus. The name of a subsequent user of

a scientific name must be separated from the scientific name by a colon.

Synonymy arrangement should be according to chronology of names, i.e. all published

scientific names by which the species previously has been designated are listed in chronological

order, with all references to that name following in chronological order, e.g.:

Family Nuculanidae

Nuculana (Lembulus) bicuspidata (Gould, 1845)

Figs 14-15A

Nucula (Leda) bicuspidata Gould, 1845: 37.

Leda plicifera A. Adams, 1856: SO.

Laeda bicuspidata Hanley, 1859: 118, pl. 228 (fig. 73). Sowerby, 1871: pl. 2 (fig. 8a—b).

Nucula largillierti Philippi, 1861: 87.

Leda bicuspidata: Nicklés, 1950: 163, fig. 301; 1955: 110. Barnard, 1964: 234, figs 8-9.

Note punctuation in the above example:

comma separates author’s name and year

“semicolon separates more than one reference by the same author

full stop separates references by different authors

figures of plates are enclosed in parentheses to distinguish them from text-figures

dash, not comma, separates consecutive numbers

Synonymy arrangement according to chronology of bibliographic references, whereby

the year is placed in front of each entry, and the synonym repeated in full for each entry, is

not acceptable.

In describing new species, one specimen must be designated as the holotype; other speci-

mens mentioned in the original description are to be designated paratypes; additional material

not regarded as paratypes should be listed separately. The complete data (registration number,

depository, description of specimen, locality, collector, date) of the holotype and paratypes

must be recorded, e.g.:

Holotype

SAM-—A13535 in the South African Museum, Cape Town. Adult female from mid-tide region, King’s Beach

Port Elizabeth (33°51’S 25°39’E), collected by A. Smith, 15 January 1973.

Note standard form of writing South African Museum registration numbers and date.

7. SPECIAL HOUSE RULES

Capital initial letters

(a) The Figures, Maps and Tables of the paper when referred to in the text

e.g. ‘... the Figure depicting C. namacolus...’; *. . . in C. namacolus (Fig. 10)...’

(b) The prefixes of prefixed surnames in all languages, when used in the text, if not preceded

by initials or full names

e.g. Du Toit but A.L.du Toit; Von Huene but F. von Huene

e.g. Therocephalia, but therocephalian

Punctuation should be loose, omitting all not strictly necessary

Reference to the author should be expressed in the third person

Roman numerals should be converted to arabic, except when forming part of the title of a

book or article, such as

“Revision of the Crustacea. Part VIII. The Amphipoda.’ ee,

Specific name must not stand alone, but be preceded by the generic name or its abbreviation

to initial capital letter, provided the same generic name is used consecutively. :

Name of new genus or species is not to be included in the title: it should be included in the

abstract, counter to Recommendation 23 of the Code, to meet the requirements of

Biological Abstracts.