Observations of the Reproductive Cycle of Petrolisthes Title japonicas (de Haan) (Anomura: Porcellanidae)
Author(s) Nakasone, Yukio
琉球大学理工学部紀要. 理学編 = Bulletin of Science & Citation Engineering Division, University of Ryukyus. Mathematics & natural sciences(15): 127-135
Issue Date 1972-03-01
URL http://hdl.handle.net/20.500.12000/23471
Rights 127
Observations of the Reproductive Cycle of Petrolisthes japonicus (de Haan) (Anornura: Porcellanidae)
Yukio NAKASONE*
Summary
The reproductive cycle of Petrolisthes japonicus (de Haan) was studied in Fukuoka during 1966-67. 1) The ovigerous females were found in the crab population from the end of May to the beginning of November. The reproductive season was approximately fi ve months. 2) The females of the species produced three broods per year and the egg deposition occurred at every about six weeks during the reproductive season. The females had ova which will produce fourth brood., but their ova were not able to develop into eggs, probably because of low water temperature and were absorbed. 3) The start of maturity in the females occurred at about 4.1 mm in carapace length, although a single ovigerous female (3. 3mrn) less th.ln i.1 mm was found in the samples. Ovigerous females ranged from 3.8 to 8.5 mm in carapace length and from 30 to 381 in the number of eggs. 4) The females of the species may incubate in a year after hatching,
Introduction
The reproductive cycles of porcellanid crabs have been reported by some workers. Petrolisthes cinctipes from California reproduced throughout almost the entire year (Boolootian et al.) I,> Petrolisthes eriomerus found in Puget Sound, Washington had two broods of eggs during the reproductive season(Knudsen)2). Petrolisthes e/ongatus, which is common in New Zealand, reproduced throughout the year (Greenwood),3) while Wear') suggested that the most females of the species occurred at least two broods· of eggs per year. Petrolisthes japonicus (de Haan) (lap. nam. Iso-Kanidamashi) is one of the most common porcellanid crabs in Japan and the adults are usually found under stones in the intertidal zone. The reproductive cycle of the species is not known, but MiyakeS) stated that the ovigerous females were found in July and August. This paper is a record of field observations on the reproductive cycle of Iso-Kanidamashi.
Materials and Methods
The samples used in this study were captured by hand from under stones in the intertidal zone of Tsuyazaki, which is shown in Fig. 1, Fukuoka Prl,!fecture. All samples used for the annual reproductive cycle were several times collected from the
Recei ved: Sept. 30, 1971 *General Education Division, University of the Ryukyus. 128 NAKASONE: Observations of the Reproductive Cycle of Pelrolislhes japonicus (de Hu n) (Anomura:Porcelianidae)
Fig. 1. Showing stony shore exposed at low tide. Tsuyazakl. Pukuoka.
population or thCl above locality monthly over a year f rom June 1966 10 May 1967 aDd they were preserved in 50/0 forma lin. Females arc easi ly distinguished by the presence of the g~nita l opening on the coxa of second wa lking leg. ~easurements were made with a .pai~ of dividers ~n d a ruler. Carapace le.ng th was measured from t he tip of the rostrum to the posterior margin. The size of eggs was measured using all-purpose projector. Ova described in this paper indicated those that had been able to confirm them under a low power binocular microscope and they were not observed histologically. The number of eggs removed from pleopods was counted with a counter.
Result. and DIKussion
Number of females collected monthly and its size ra nge, percentage of ovigerous females and size of the smallest ovigerous female, a nd size of the smallest female with ova are gi ven in Table 1. During the period frofY) April to November 1966, female crabs collected at each time of the survey were distinguished into four types, such as (1) non-ovigerous females with o va, (2) ovigerous females without ova, (3) ovigerous females with ova, (4) females with prehatch eggs a ttached 10 the pleopods. The results are shown in Fig. 2. Egg deposition began toward the end of May and increased rapidly unt il about July 20, when over 93.5% of females had ellS attached to the pleopods. AI the middle of August, the ovigerous females somewhat decreased and showed 79.6%. The percenlage of the ovigerous females during the period from about August 20 to the end of September showed an approximately steady peak. though the most high peak was 92 .0% at the middle of September, and then the percentage of the ovigerous females decrea~ed rap idly and came to almost zero in Ihe fi rst weekof·November. Thedaia' Sullest "tha t the rep'roductive sei$on ' c~ntinues from June 10 October in the populalie:n, L c-, approximately rive months. The field records Bull, Sciences '" Engineering Div" Univ, of the Ryukyus, (Math, &; Nat, Sci,) 129
Table I, Showing number of females, size range, percentage of ovigerous females., the smalJe~t size of females, and sex ratio in the samples of PetTolisthes japonicus collected monthly at Tsuyazaki" from June 1966 to May 1961.
Month No, of Size range % of Size of Size of females (in mm) ovig, ~ smallest smallest ¥ examined ovig, ~ with ova (I n mm) (in mm) 1966 June 180 2,8-8.5 31,1 '.7 '.7 1/1,1 July 405 3,5-8,3 83.7 3.8 '.4 1/ 1,1 Aug, 313 4.3-7.8 77 ,3 '.3 4.1 1/1,7 Sept, 679 4. 3-8.3 82,2 '.3 '.3 1/2.1 Oct, ". 4.1-8.3 21,6 '.7 5.1 1/1,4 Nov. 618 3.1-8.0 0.2 6.' 6.2 1/ 1.5 0.,. 302 3.3-7.6 o o o 1/1.6 1967 Jan. 654 2.1-7.8 o o o 1/1,3 Feb, 396 2.9-7.6 o o o 1/1.4 Mar, 71. 2,8-7.8 o o o 1/1.7 Apr, 869 2.5-8.1 o o 5.2 1/2.3 Mo, 73. 3.1-1,9 0.5 6.6 4.1 1/1.8 from about July 10 to the end of September showed t hat between 80 and 93% of the females were reproductively active (Pig, 2) . During the reproductive season 2020 ovigerous females were captured. 1729 of them (about 85010 ) had ova which were large and bright orange. This supports the idea that t wo or more broods may be produced by the females in the population during the reproductive season. Fig. 2 shows the season of egg deposition or hatching for fi rst, second, and third broods as far as the data will permit,
'00 f ~ ," "..
f ~ < ,...
Fig. 2. Reproductive cycle of Petrolisthes japonicu$. Ts uyazaki. Fukuoka, 1966.
As shown in Fig. 2. non-ovigerous females began havi ng ova early in April and reached the peak on May 25 and then came to nearly zero at the midd le of July. Egg deposition for the first brood began toward the end of May and continued until about July 20, when a large number of females (about 93%) were in berry. At this 130 NAKASONE: Observations of the Reproductive Cycle of Petrolisthes japonicus (de Haan) (Anomura: Porcellanidae) time over 58% of the ovigerous females had prehatch eggs. Eye pigment of the embryo of the first brood became visible at about June 20, when a few ovigerous females again began having ova which will produce the second brood. The ovigerous females with second brood of ova showed a minimum value of 23% at the middle of July. In the early part of July, a fact that the ovigerous females with second brood of ova decreased and the ovigerous females without ova increased suggests that some individuals begin the hatching of the first brood of eggs. But, a large number of individuals begin the hatching after July 20, for a sharp falling-off in the percentage of individuals with prehatch eggs is noticed, and continues until about the middle of August. Judging from the fact that ova within the ovaries of females bearing the first brood of eggs showed a considerable degree of maturity, it seems that the egg deposition of the second brood occurs very shortly after the hatching of the first brood begins and that time is probably about the middle of July. That is, the egg deposition of the second brood begins about the middle of July. The peak of females bearing the second brood of eggs is evident at about August 20, when over 84% of the ovigerous females also had ovaries swollen with large bright orange ova which Oct. 5 ~ l
l- • 10 • I L I 1 Sept. - - ~ 20 - 10 I- ---I May l- I .- I 5 I- Apr. , L I t • • • • I .~ 3.9 4.3 4.7 5.1 5.5 5.9 6.3 6.7 7.1 7.S 7.9 Carapace length (mm) Fig. 3. Size distribution of females bearing ova collected from the crab population at Tsuyazaki from June 1966 to May 1967. Bull. Sciences &. Engineering Div., Univ. of the R)'uk)'us.{Math. &. Nat. Sci.) 131 22 18 - - 2 J ~ 3.9 4.3 4.7 5.1 5.5 5.9 6.3 6.7 7.1 7.5 7.9 8.3 Carapace length (mm) Fig. 4. Size distribution of ovigerous females. will produce third brood. The appearance of the second brood tends to offset the hatching of the first brood as far as the percentage of total ovigerous females is concerned. Thus. Fig. 2 shows an approximately stead), peak from about Jul)' 20 to the first week of August. The ovigerous females found during the period f rom the middle of July to that of August contain both the females with first brood of eggs and the females with second broqd of eggs. Accordingl)" that the ovigerous females bearing ova decreased at the middle of August suggests the completion of hatching of the frist brood of eggs. The prehatch eggs of brood number two increased after August 5 and showed the peak of 54% on August 20. After that, the facts that the ovigerous females with third brood of ova decreased and the ovigerous females wi thout ova increased and that the percentage of females bearing prehatch eggs decreased suggest that the hatching of the second brood occurs after August 20. That is, shortl)' after the peak of females bearing the second brood of eggs is reached hatching occurs and continues until about the middle of September. Egg deposition of the third brood begins toward the end of August. On September 5, over 40% of individuals attached new eggs to 132 NAKASONE: Observations of the Reproductive Cycle of Pelrolisthes japonicus (de Hun) (Anomura: Porcellanidae) the pieopods were found. This also supports the possibility that the egg deposition of the third brood occurs about the end of August. Therefore. the third brood appears "" h h. ,,, ~ n.",. ~• ~ 0 •~ I u" •. ,.". 3.] L~ ; .\1 Cl 4.7 S. I S.~ :> .9 C,.:l 6.7 1. 1 7.S Carapace length (mm) Fis:. 5. Size distribution of females collected from the crab population at Tsuyazaki from June 1966 to May 1967. Black part shows ovigerous females. Bull. Sciences &: engineering Div.. Univ. of the Ryukyus.(Malh. &: Nat. Sci.} 133 very shortly after the hatching of the second brood begins, showing that there is a very short duration when the females are not attached eggs to the pleopOOs. Thus, the egg deposition of the third brood begins toward the end of August and reaches its peak at the middle of September. At this time, over 92% of females were in berry and about 80% of the females had ova which will produce fourth brood. The appearance of the third brood offsets the hatching of the second brood as far as the percentage of ovigerous females is concerned. Thus, Fig. 2 shows an approximately steady peak from about August 20 to the middle of September. Hatching of the third brood begins after the middle of September and reaches its peak about the early part of October and is completed by the end of October or the beginning of November, when less than 0.2% of the females still had prehatch eggs. A fact that the percentage of ovigerous females with ova increased at the middle of September suggests the possibility of fourth brood. but their ova are not able to develop into eggs, probably because of low water temperature and may be absorbed. This is clear from the facts that ovigerous females did not increase toward the end of September or early in October and that females bearing ova were not entirely found after the beginning of November. According to ThorsonS) and Stephens1) reproductive cycle and spawning depend on external conditions such as temperature and light. Thus, it may be concluded that the females of Iso·Kanid amashi produce three broods per year and it seems that the egg. deposition occurs at every about six weeks during the reproductive season. The relationship between females bearing ova and carapace length is shown in Fig. 3. The size distribution of all the ovigerous females is shown in Fig. 4. As will be seen from Fig. 4, breeding is more prevalent in females in the 5.3 to 6.1 mm size group than in females on either side of this group. Size distribution of the females captured during a year from June 1966 to May 1967 is shown in Fig. 5. Fig. 5 indicates that the larvae hatched in and after July grow into the young crabs which appear on the shore (the adult habitat) in and after November and that the females less than at least 4.5 mm in carapace length are those which hatched after the beginning of July. Accordingly, that the smallest female bearing ova was 4.1 mm in May (Table 1) suggests that sexual maturity in the females is achieved when the carapace length measures approximately 4.1 mm in about ten months after hatching, although a single ovigerou5 female (3.8 mm ) less than 4.1 mm was found in the samples. However. the sexual maturity mentioned above is not of the result of observation obtained by histological examination. Furthermore, as will be seen from Fig. 5 and Table I, the females of the species may incubate in a year after hatching. The eggs within the egg masses of 850 female crabs were counted with a counter. But, using 5 examples (50 females), the relationship between number of eggs carried and carapace length is shown in Fig. 6 and each point represents an average for 10 females. A line is fitted by least squares method. Ov igerous females ranged from 3.8 to 8.5 mm in carapace length and from 30 to 381 in the number of eggs. 20 eggs were measured to determine their average size, which showed 0.75xO.67 mm. 134 NAKASONE: Observations of tbe Reproductive Cycle of Petroli5lbcs japonicus (de Haan) (Anomura: Porcellanidae) 220 180 1'0 y = -161.72+57 .08X 5.0 5.5 6.0 6.5 7.0 7. ' Carapace length(mm) Fil. 6. Relationsbip between'number of egp carried and carapace length. Line Htted by least squares method. The stomach contents were examined in a few samples and they consisted of diatoms and microorgani sms, which had not been able to analyze. Acknowledgments I wish to express my thanks to an emeritus professor Sadayoshi MIYAKE and Dr. Teru Aki UCHIDA of Kyushu University for their invaluable advice and encourage ment. Thanks are also due 10 Professor Shinsho NISHIJIMA of the University of the Ryukyus for his he lpful suggestions. References (I) Boolootian. R. A... A. C. Giese. A. Farmanfarmaian, and J. Tucker: Reproductive cycles in five west coast crabs. Physio!. Zoo!. 32 (959). 213-220. (2) Knudsen. J. W. : Observations of the reproductive cycles and ecolOIY of the common Brachyura and crablike Anomura of Puget Sound. Washington. Pacif. Sci. 18 (19&4) . 3-33. (3) Greenwood, J. G. : The larval development of Pttro/isthts tlO llg1tllS (H. Milne Edwards) and Ptlralisthts 1I0VOtua/onditU Filhol (Anomura, Porcellanidae) with notes on breeding. Cruslaceana 8 (1965) . 235-307 . (4) Wear. R. G. : Breedinl cycles and pre-zoea larva of PttroIiS'MS tlollgat MS (Milne Edwards. 1837) (Cru ~ tacea, Decapoda). Trans. Roy. Soc. N. Z. 5 (1965). 169- 175 . (5) Miyake. S. : A list of the decapod Crustacea of the Sea of Ariat I. Kyusbu. Rec. <>CUDOlf. Wks. Japan. spec. 5 (19&1). 165-178 . (6) Thorson. O. : Reproduction and larval ecology of marine bottom invcrtebrates. BioI. Rcv. Bull. Scjence~ & E ngiocering Div., Univ. of the Ryukyus. (Math. & Nat. Sci.) 135 25 (1950).1-45. (7) Stephens. G. J.: Mechanisms regulating the reproductive cycle in the crayfish. Cambarus. 1. The female cycle. Physio!. Zoot. 25 (1952) . 70- 84 .