Hayasaka Kazuko

Kato Mutsuo

Matsuda Tatsuro

紀要類（bulletin）departmental bulletin pape

Kato, Mutsuo

Hayasaka, Kazuko

Matsuda, Tatsuro

Tohoku University Repository (TOUR) / 東北大学機関リポジトリ

ECOLOGICAL STUDIES ON THE MORPHOLOGICALVARIATION OF A SESSILE BARNACLE, CHTHAMALUSCHALLENGERI III. VARIATION OF THE SHELL SHAPEAND OF THE INNER ANATOMICAL FEATURE INTRODUCEDBY THE POPULATION DENSITY著者 Kato Mutsuo, Hayasaka Kazuko, Matsuda Tatsurojournal orpublication titleThe bulletin of the Marine Biological Stationof Asamushi, Tohoku Universityvolume 10number 1page range 19-25year 1960-03-25URL http://hdl.handle.net/10097/00131087BULLltTIN OF THE MARIN~ BIOLOGlCAL STATtON OF ASA?IIUSHl, VOL. X, NO, I. 1960 ECOLOGICAL STUDIES ON THE MORPHOLOGICAL VARIATION OF A SESSILE BARNACLE, CHTHAMALUS CHALLENGER! III. VARIATION OF THE SHELL SHAPE AND OF THE INNER ANATOMICAL FEATURE INTRODUCED BY T>HE POPULATION DENSITY'·" By MuTsuo KAT6, KAZUKO HAYASAKA.and TATSUR6 MATSUDA tuJ!jill!l!J!/ilt · .ijlt!i('llFf · ~lEEJ!ii~B Biological Institute, TOhoku University, Sendai, japan INTRODUCTION Concerning the variation of the external appearance of the sessile barnacle, there have been published numerous works by many authors (Neu 1935, Utinomi 1955, Barnes and Powell 1950 etc.) and the present writers have investigated on the external feature of a sessile barnacle, Chthamalus challengeri from the view-point of the population ecology (Kato et al. 1960). But the morphological change of the inner anatomical feature had been scarcely studied in relatien ·to the above mentioned variation of the external appearance. In the present paper, the relation between the external appearance of the shell of Chthamalus chaUengeri and the anatomical feature of the body in the shell was investigated. MATERIAL AND METHOD In the neighbourhood of the Marine Biological Station of Asamushi in Aomori Prefecture, various clusters consisting of fairly large number of Chthamalus challengeri having ~espectively different population density were obtained from the inter-tidal rock surface. The individuals thus obtained were decalcified and thereafter the celloidin and paraffin methods were used for preparation of the microscopical observation which were also applied to the naked body. For the statistical treatments the following measurable characters were chosen (Fig. I). 1) This paper is dedicated to Professor Tadao Jimbo for his 63rd birthday. 2) Contributions from the Marine Biological Station of Asamushi, Aomori Ken, No. 260. 20 i'vl. KA1·6, K. HAYASAKA and T. MATSUDA -===·===T -r H h ~~~LJ ; -------r H ~====~J ~------·6'------~ Fig. 1. Schemata showing the internal feature of Chthamalus challengeri . 3 and 4) . Shell height (H) , breadth and length of the shell base (B and B'), depth and length of the mantle cavity (h and b), length and thickness of the body (1 and w), inclination degrees of rost. um (a) and scutum ({J) in the lo1gitudinal section of the shell, inclination degree of scutum ({3') in the cro:;s section at about the anal port ion of the body, incl ination degree of the body (y) to the shell valve to which the body attaches. RESULTS AND D ISCUSSIONS I. The Modification of the Morpho-logical Featw'e of the Body and of the Arrangement of VariMtS Inner 01'gans introdnced by the Population Density. (1) The solita~y barnacle (Figs. 2, The solitary barnacles which are conical in the external appearance were Fig. 2. Sparsely distributed conical barnacles . Fig. 3. The longitudinal section of a solitary barnacle. SHELL SHAPE AND ANATOMICAL FE ATUH.E OF CI-ITHAMALUS Fig. 4. The longitudinal s3ction of a conical barnacle (paraffin section). obtained from the sparsely distributed population (Fig. 2). As is obviously shown in the longitudinal section of the shell (Fig. 3), the body occupies the greater part of the mantle cavity and lies nearly horizontally in it. The scutum of the opercular valves is also nearly horizontal. In Fig. 4 it is shown that the turning of the alimentary canal is rather simple. (2) Barnacle which is loosely in contact with only one or two other individuals. In Fig. 5 two barnacles adjacent is shown, one is a longitudinal section at about the median line of the body and the other is crossed at the anterior part of the body. The shell height becomes a lit tle high and the inclination of rostrum is strengthened and thus the scutum and also the body axis become somewhat inclined. Fig. 5. Two barnacles, one is sectioned longitudinally and the other cross sectioned. 22 ::\!. KATO, K H AYASAKA and 't MATSUDA Fig . 6. The cross-sections of ba rnacles obtain ed from the rather thinly distributed population as compared with those in Fig. 5. Fig. 6 shows the cross section at about the pharyngeal portion of an individual which was obtained from the rather thinly d istributed population as compared with the above individuals, and it is noted that the egg sacs are situated at the lateral sides of the body. (3) Barnacles which are closely in contact with each other (F igs. 7, 8 and 9). Fig. 7. The longitudinal section of barnacle obtained from the densely distributed population. The shell is remarkably high and cylindr ical in form and the lateral valves are nearly perpendicular Fig. 8. The longitudinal section of densely populated barnacle. SHELL SH APE AND ANATO::\HCAL l'EAT URE OF CHTJ·TA!VIALUS 23 (Fig. 7), occasionally the lower part of the cylindrical shell is rather narrow as compared with the width of the upper opercular portion (Fig. 8). Together with this phenonemon the inclination degree of the scutum becomes increased. Th e m:tntle cavity becomes a}so narro·w and cylindrical in parallel with the elongation of the shell, but as the shell is superior t o the mantle cavity in elongation, the l;:~tter occupies only the upper portion of the cylindrical shell cavity (Fig. 9) . Owing to the stress of t he elongated mantle cavity, the body axis tends to increase its inclina-tion degree. It must be noticed that the body occupies only the upper portion of the elongated mantle cavity and the alimen-tary canal tends to undulate and moreover is bent strongly at th e attaching portion of the body to the shell, and with the elongation of the mantle cavity the egg sacs move downwards to the lower part of the cavity. Fig. 9. The cross-section of barnacle obtained from the densely d istributed population. II. The Statistical Treatment of the Modification of the Anatom1:cal Featm•es of the Barnacle introd~tced by the P opulation Density. Concerning the relation between the modification of the shell and the arrangement of various inner organs, further investigation was done from th e statistical view-point (Fig. 10). As it was ascertained in the previous paper (I<at6 et al. 1960) that th e antagonist ic relation is recognized between the shell height and the size of the shell base, the value of H / B or H / B' was used as an index of the shell shape or of the population density. (1). Changes in the shape of the mantle cavity (h / b) and the rate of body length to the width of the mantle cavity (1/ b) are parallel with the elongation of the shell (H/B), namely with the increasing of the population density, and these changing modes are similar t o the inclination mode of the scutum (/3) . From the above it is known that the mantle cavity elongates with the shell elongation and the inclination degree of the scutum also increases. As the body increases relatively in i ts length as compared with the width of 24 M. KATi). K. HAYASAKA and T. MATSUDA h/H 1.0 ~,-----------, h/br·--------1.8 I .8 • .6 ' 8060 0 1.4 I 1/bf-'~~~~~~~-1.2~ 1.0 . • • •• .8F~~~~~-..........J f; ' 50 ::4'. ~·.8. 1.2 1.6 .2.0:1·::~~~~~~~~~ i r. . 1.2 1.6 2.0 H/B .4 .8 1.2 1.6 2.0 H/8' Fig. 10. The relations among the various dimensional characters of barnacles with special reference to the population density. the mantle cavity, the body axis tends to incline. It is noticeable that the increasing rate of these three values becomes larger with the increasing of the value of H JB, namely with the increasing of the population density. (2). The rate of the depth of the mantle cavity to the shell height (h/H) decreases with the increasing of the shell elongation attaining to a limiting value. It is known from the above that the elongation of the mantle cavity is inferior to that of the shell. Changes in the degree of the inclination of rostrum (a), scutum ( (3') and body axis (y) are respectively similar in their modes. The value of y changing in parallel with the elongation of the shell seems to relate closely to the already mentioned inclination of the body axis and to the strong bending of the alimentary canal. CONCLUSION From the above mentioned observations and the statistical treatments, the modification of the arrangement of inner organs of Chthamalus chaUengeri introduced by the population density is summarized as follows : I. The conical shell attains a cylindrical form with the increasing of the population density. 2. Owing to the crowding of individuals the shell plates (lateralia) and SHELL SHAPE AND ANATOMICAL FEATURE OF CHTHAMALUS 25 opercular plates (scuta) increase the inclination degree and therefore the mantle cavity becomes narrow in width and cylindrical in form accompanied with the elongation of the shell. 3. Thus the body situated horizontally in the mantle cavity changes to become inclined being pressed by the wall of the narrowed mantle cavity. Moreover the alimentary canal becomes undulated and bends strongly at the portion where the body attaches to the shell. 4. Corresponding to the elongation of the mantle cavity, the body situates in the upper portion of the said cavity and the egg sacs which are at the lateral sides of body in a conical shell move downwards to the base of the mantle cavity. LITERATURE CITED BARNES, H. and H.T. PoWELL, 1950. The development, general morphology and subse-quent elimination of barnacle population, Balanus crenatus and B. balanoides, after a heavy initial settlement. Journ. Animal Ecol., 19. KAT6, M., K. HAYASAKA and T. MATSUDA, 1960. Ecological studies on the morphological variation of a sessile barnacle, Chthamalus challengeri I. Changes of the external appearance introduced by the population density. II. Constitutional characters of the Chthamalus population with special reference to the stratification of the Chthamalus zone. Bull. Marine Bioi. Stat. Asamushi, 10: 1-17. UTINOMI, H., 1955. Studies on the Cirripedia of Japan, III. Ecological evidences. Bull. Biogeograph, Soc. Jap., 16-19. 

ECOLOGICAL STUDIES ON THE MORPHOLOGICAL VARIATION OF A SESSILE BARNACLE, CHTHAMALUS CHALLENGERI III. VARIATION OF THE SHELL SHAPE AND OF THE INNER ANATOMICAL FEATURE INTRODUCED BY THE POPULATION DENSITY

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ECOLOGICAL STUDIES ON THE MORPHOLOGICAL VARIATION OF A SESSILE BARNACLE, CHTHAMALUS CHALLENGERI III. VARIATION OF THE SHELL SHAPE AND OF THE INNER ANATOMICAL FEATURE INTRODUCED BY THE POPULATION DENSITY

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