Puberty Molt Research Articles

Postlarval Stages and Growth Patterns of the Spider Crab Pyromaia Tuberculata (Brachyura, Majidae) from Laboratory-Reared Material

The spider crab Pyromaia tuberculata was introduced into southeastern Brazil; ovigerous material was collected and reared in the laboratory. Morphologic changes and growth patterns of postlarval development are reported. Results show that within-stage size variation is lowest in mature stages, especially in the case of females in which there is an apparent size threshold for the last juvenile stages to undergo the puberty molt. A prepuberty molt taking place at the fourth crab stage is indicated by analyzing the allometric growth of the abdomen in females. In contrast, the same procedure using the allometric growth of chelae failed in detecting both the prepuberty and puberty molts in males. Conversely to females, which develop a complex brood chamber at the puberty molt, the enlargement of chelae was not consistent in all postpuberty males. The short instar sequence of this species, in no case exceeding nine stages, is marked by conspicuous morphologic alterations achieved at each molt. Almost all stages can be identified by examining diagnostic features of rostrum, abdomen, sternum, and pleopods.

Growth to maturity of juveniles of the spider crabs Hyas coarctatus Leach and Inachus dorsettensis (Pennant) (Brachyura: Majidae)

Specimens of the spider crabs Hyas coarctatus and Inachus dorsettensis were reared in the laboratory under ambient temperature conditions. Individuals were retained until they had undergone two moults, or moulted to the terminal instar: they were then replaced by fresh specimens. The percentage increment was recorded for each moult, and the duration for each intermoult period. Both intermoult period and percentage increment either declined with increasing temperature or showed no response. The effect of body size on these variables tended to reflect that expected in species with determinate growth—intermoult period generally increased with size, whereas percentage increment remained unchanged. Percentage increment was compared between juvenile moults and the puberty moult in both this and earlier studies. In males, the puberty moult increment was smaller than juvenile increments, and this is tentatively related to the diversion of resources to the large puberty increase in chelar size. In females, the puberty moult increment was either larger or smaller, dependant on whether the ovaries matured after or before the puberty moult, respectively—again a reflection of resource allocation. Growth curves constructed from the laboratory data were compared with those based on field studies. These analyses emphasised that seasonal constraints in natural populations could compromise predictions from laboratory experiments.

Chromatic alteration in Arenaeus cribrarius (Lamarck) (Crustacea, Portunidae): an indicator of sexual maturity

Some individuals of the species Arenaeus cribrarius (Lamarck, 1818) bear a characteristic pink abdomen, which is notably different from the usual white coloration. The incidence of this chromatic alteration was determined for a single population and its relation with other individual variables were examined. The individuals were monthly collected from May, 1991 to April, 1993, in Ubatuba, São Paulo, with the aid of a shrimp fishery boat provided with double-rig trawling nets. All specimens were sexed, measured (CW = carapace width), distributed in 10-mm size classes and classified according to growth phase (juvenile and adult), molting condition and development stage of gonads. The occurrence of pink-colored morphs was also recorded. From a total of 2,096 collected individuals, only 60 females (nine of those ovigerous) presented a pink-colored abdomen, which represents 2.9% of the whole sample and 5.2% of the females. Almost all of them were intermolt individuals (96.6%) and 63.3% showed mature gonads. According to published data, size at the onset of functional maturity in A. cribrarius females is around 60 mm CW, from which the incidence of pink morphs and ovigerous crabs were recorded. The obtained results suggest that such a chromatic alteration is associated to sexual maturity in these females. This characteristic may enhance the attraction potential for mating, shortly after the puberty molt.

Decapod crustacean chelipeds: an overview.

The structure, growth, differentiation and function of crustacean chelipeds are reviewed. In many decapod crustaceans growth of chelae is isometric with allometry level reaching unity till the puberty moult. Afterwards the same trend continues in females, while in males there is a marked spurt in the level of allometry accompanied by a sudden increase in the relative size of chelae. Subsequently they are differentiated morphologically into crusher and cutter making them heterochelous and sexually dimorphic. Of the two, the major chela is used during agonistic encounters while the minor is used for prey capture and grooming. Various biotic and abiotic factors exert a negative effect on cheliped growth. The dimorphic growth pattern of chelae can be adversely affected by factors such as parasitic infection and substrate conditions. Display patterns of chelipeds have an important role in agonistic and aggressive interactions. Of the five pairs of pereiopods, the chelae are versatile organs of offence and defence which also make them the most vulnerable for autotomy. Regeneration of the autotomized chelipeds imposes an additional energy demand called "regeneration load" on the incumbent, altering energy allocation for somatic and/or reproductive processes. Partial withdrawal of chelae leading to incomplete exuviation is reported for the first time in the laboratory and field in Macrobrachium species.

Growth pattern of isolated prawns of Macrobrachium borellii (Crustacea, Decapoda, Palaemonidae)

Summary The aim of this study is to analyze individual growth of the freshwater prawn Macrobrachium borellii (Crustacea, Decapoda, Palaemonidae) analyzing pre- and postmolt cephalothorax length data in laboratory-reared animals. An isometric increase of Cl was observed in juveniles (slope: 1.01) and a negative allometric for females and males (slope: 0.85 and 0.87, respectively). The duration of intermolt period increases with the size, being linear in juveniles and positively exponential in both sexes. The size increase was larger in males than in females but there was no significant difference. The relationship between growth rate and intermolt period was negatively exponential in all of the groups. Growth by molting decreases with the size in a negatively exponential form. Values for males and females were not statistically different, but juvenile and adult values were. The juvenile phase is marked by a change in the growth level and may be due to the puberty molt. The difference in the male-female allometric level was relatively small and in some cases of uncertain significance.

GROWTH AND REPRODUCTION OF THE GRAPSID CRAB PLAGUSIA DENTIPES (DECAPODA: BRACHYURA)

ABSTRACT Growth and reproduction of the grapsid crab Plagusia dentipes were examined from February 1990 to January 1991 at Banda, Tateyama, Chiba Prefecture, Japan. Ovigerous females occurred from October-December. Small juveniles recruited from April-June. It was concluded that the duration of the larval stages was at least 6 months. After settlement, juveniles of approximately 7-mm carapace width reached 25-30-mm carapace width by October. A section of this cohort matured through a puberty molt in October-November of that year. At the puberty molt, secondary sexual characteristics, such as the elongation of the chela in the male and the enlargement of the abdomen in the female, occur. The brood size of these females ranged from 10,000— 50,000 eggs. Growth stopped during the winter from December-February and progressed with a rise in water temperature after March. In autumn, both crabs that matured and those that failed to mature in the previous year participated in reproductive activity. Females recruited in the previous year breed probably twice in a season and spawn 100,000-200,000 eggs at a time. Females reproduced in their third autumn. However, further growth and reproduction after this were not clarified in this study.

LIFE CYCLE STUDIES ON THE INTRODUCED SPIDER CRAB PYROMAIA TUBERCULATA (LOCKINGTON) (BRACHYURA: MAJIDAE). II. CRAB STAGE AND REPRODUCTION

ABSTRACT Introduced populations of the spider crab Pyromaia tuberculata have become established in organically polluted bays in Japanese coastal waters. Pyromaia tuberculata is a predominant species in the epibenthic animal community in upper Tokyo Bay where summer hypoxia of bottom water causes a seasonal defaunation of the benthic community. Crabs recolonized the upper bay area after bottom oxygen recovered, settling in midfall, maturing in midwinter, and producing larvae from midspring until the return of hypoxia in summer. While all crabs in the upper part of Tokyo Bay were killed in late summer by the hypoxia, crabs, including ovigerous females, were found throughout the year in the lower part of the bay, where the hypoxia was not severe. Crabs in the lower part of the bay may be parents of recolonized crabs in the lower part of the bay. The purpose was to clarify the life cycle of P. tuberculata in a hypoxic environment. Crab growth and reproduction of P. tuberculata were studied by field surveys and laboratory experiments. Females reached maturity within 6 months after settlement, and the size of adult females tended to decrease when matured in higher temperatures. Developed eggs in which eye spots or eyes had appeared were found throughout the year. Puberty molt of the female could occur at ecdysis to the seventh crab instar. The final instar stage at which males reach maturity may vary individually from the sixth to eighth instars. This research, combined with earlier studies, demonstrates that P. tuberculata in Tokyo Bay reproduces throughout the year, and completes at least two generational cycles annually. These characteristics allow for the opportunistic exchange of larvae between temporary hypoxic and permanently healthy areas, and thus may be responsible for the ability of P. tuberculata to maintain its population in seasonally hypoxic waters.

Growth and maturation of the benthic stages of male snow crab, Chionoecetes opilio (Brachyura: Majidae)

Growth and maturation of postlarval male snow crab (Chionoecetes opilio) in an exploited Gulf of Saint Lawrence population were elucidated using size distributions in beam trawl samples taken bimonthly from April 1991 to May 1992, moult and maturity indices, and measures of growth per moult. Males develop in three stages: immature, without spermatophores; adolescent, with spermatophores but undifferentiated chelae; and adult, with spermatophores and differentiated chelae. Males change from immature to adolescent after a puberty moult, and from adolescent to adult after a terminal moult producing a final carapace width (CW) >40 mm. The slope of the regression relating post- to pre-moult CW decreases after puberty. Carapace moult increments are the same at pre-terminal and terminal moults, for a constant premoult CW. Males recruit to the legal size of 95-mm CW at instar XII, ≈8.7 years or more after settlement. The slope of the regression of gonad weight on CW is less for adult than for adolescent males owing to the formers' participation in reproduction and to greater depletion of sperm stores in large than in small adult males. Gonad weight increases with time since moult, but for large adults, did not reach levels recorded in prefishery times or in an unfished population.

サワガニの相対成長と生殖腺の成熟

The patterns of relative growth and gonadal maturation in a freshwater crab Geothelphusa dehaani were studied in a natural population inhabiting the Taniyamagawa River, Fukuoka, Japan. The relative growth in secondary sexual characteristics (SSC) with respect to carapace width (CW) was categorized into three phases, juvenile, adolescent and adult. There were two discontinuities among the phases: primary, between juvenile and adolescent, and secondary, between adolescent and adult. We fitted a regression formula to each phase of allometric growth. In both sexes, the allometric growth of SSC was not constant, and the adolescent and adult phases were clearly distinguishable. In the female, SSC appear at the abdominal segment, and the slope of the allometric regression formula increases in adolescence, and decreases in adulthood. In the male, SSC appears on one of the chelae, and the slope of the formula increases in adolescence and more in adulthood. The puberty molt occurred at the secondary discontinuity, when CW was about 18mm in males and 19mm in females. These sizes correspond to the CW which was attained at functional sexual maturity, and this was confirmed by an abrupt increase in the maturity index (MI). Accordingly, it is suggested that the marked trend in relative growth of the exoskeleton is closely related to the onset of functional gonadal maturation.

Relative Growth of the Speckled Swimming Crab Arenaeus Cribrarius (Lamarck, 1818) (Brachyura, Portunidae), Near Ubatuba, State of São Paulo, Brazil

AbstractArenaeus cribrarius is a mainly tropical crab that occurs in the Western Atlantic Ocean, Brazil being its type-locality. The species ranges from Vineyard Sound, Massachusetts, USA to La Paloma, Uruguay. Information about this species is scarce. The relative growth ofA. cribrarius was analyzed, based on some morphometric relations, where the carapace width, excluding lateral spines (CW), was used as an independent variable. A total of 403 specimens (189 males and 214 females), was collected in Ubatuba, State of São Paulo, Brazil, with otter-trawls. The animals were sexed and sorted to maturation phase (juvenile or adult). Some measurements were made: carapace (length and width excluding lateral spines), abdomen (greatest width of the fifth somite in females and the sixth in males) and major chela (greatest length, width and height, dactylus length). This study was made by the application of the power function (y=a.xb) which was fitted to the data and the pattern of growth established for each parameter by the "b"-value (constant of allometry), as positive allomctry (b>1), negative allometry (b<1) or isometry (b=1). The morphometric relations of the carapace showed a tendency to isometry. In females, the abdominal width grew in positive allometry, higher in juveniles (b= 1.33) than in adults (b=1.18). In this case, an overlap and discontinuity was noticed between the phases over a carapace width range of 55 to 70 mm, where the puberty molt occurs. The majority of relationships showed that the major chela of the males grew in positive allometry, however, the greatest allometric difference between the phases was observed towards the propodus length with 1.09 as juvenile and 1.26 as adult "b"values. In the males, this variable showed an inflection between the CW range of 45 to 55 mm, where the transition to the maturation phase occurs. The relative growth of this species is similar to those of previously studied species. This indicates, that the propodus length and the abdominal width are the morphometric variables most appropriate to estimate the size at the beginning of the sexual maturity for males and females of this species, respectively.

Relative Growth and Sexual Dimorphism in the Red Frog Crab Ranina ranina (Decapoda: Raninidae).

The relative growth of several body parts and the morphology of pleopods were examined in reared and captured individuals of Ranina ranina. Sexual dimorphism occurred in the pleopods at instar I, on the abdomen of individuals over 34mm carapace length, and on the cheliped in individuals over 70mm carapace. In females puberty molt was estimated to occur at 40-45mm carapace length, using the relative growth of abdomen width. In males the relationship between dactylus or propodus length of the cheliped and the carapace length was described by two or three power regression equations. The point of contact of the logarithmically transformed linear equations was 26 and 74mm in dactylus length and 73mm in propodus length. A growth-reproduction model of R. ranina based on changes in the relative growth is discussed.

Aspects Of The Biology of the Deep-Sea CrabGeryon TrispinosusFrom the Porcupine Seabight

A study was made ofGeryon trispinosus(Herbst) from the Porcupine Seabight in the north-east Atlantic, based on detailed examination of 687 specimens, and carapace length data for a further 2000. Evidence indicates that males become sexually mature at 30–35 mm carapace length, and females between 12 and 15 mm. There is probably a terminal anecdysis, in males at 55–65 mm and in females at 45–50 mm. The chelae show limited heterochely and marked right-handedness in both sexes. Relative growth in chelae and abdomen followed expected patterns, except that the right chelae of males decreased in relative size at the puberty moult. Seasonal reproduction is indicated: laying in September/October, hatching the following May, and settlement from the plankton in August/September.

Growth and reproduction in the freshwater crab, Potamon fluviatile (Decapoda, Brachyura)

SUMMARY. 1. The patterns of relative and absolute growth and the reproductive biology of the freshwater crab Potamon fluviatile were studied in a natural population inhabiting a hill stream close to Florence, Italy, over an annual cycle. Periodical inspections of a stretch of the stream were made and morphological and anatomical analysis carried out.2. As in other decapods, the females are smaller than the males (they can however occasionally reach larger dimensions). This may be determined by a lengthening of the moulting interval in the females, by their higher energetic cost of reproduction (since reproduction occurs simultaneously with moulting, at least in this habitat) and/or by a higher mortality rate resulting from the risks associated with carrying eggs and vagility.3. The analysis of relative growth in secondary sexual characters (abdomen width and major chela length) with respect to carapace length, shows that the pre‐puberty and puberty ecdysis occur at 15 and 35 mm carapace length respectively, which was also confirmed by the gonad weight, vas deferens in males, and the onset of vitellogencsis in females.4. A delay between anatomical and functional (i.e. the ability to copulate successfully) maturity was observed in the males. Being larger may be an advantage in intra‐sexual competition for mating, but larger males, being more vagile, are also more likely to meet receptive females. The females may mate before their puberty moult and store sperms in their seminal receptacles for when they attain full maturity; this could be adaptive since opportunities of encountering males are few and far between in their adult phase, characterized by their vagile and amphibious habits.

Sexual differences in the absolute growth pattern of the Indo‐Pacific sandy shore crab Matuta lunaris

The absolute growth pattern of Matuta lunaris (Forskål) is assessed, based on moult increment data and analyses of size frequency distributions. Both sexes show determinate growth with maturity occurring at the terminal puberty moult. However, Matuta lunaris is unusual as the sexes differ markedly in their growth patterns. Males mature at a larger size than females and grow to a larger maximum size. Male growth is characterized by relatively constant moult increments and an unknown and possibly variable number of immature instars with widely overlapping size ranges. In contrast, female growth is characterized by relatively large moult increments and a fixed number of instars, each with restricted size ranges.

Larval and postlarval growth of individually reared specimens of the common shore crab Carcinus maenas (L.)

Specimens of Carcinus maenas (L.) from the Isle of Man were reared individually at 15 and 20 °C under controlled conditions from hatching to the puberty moult. Survival was monitored and for every specimen the size and duration of each instar was recorded. Survival with time was better at 15 ° C but survival to a given instar was higher at 20 ° C. Survival was generally good, until heavy mortality followed the puberty moult. The puberty moult was consistently the 11th postlarval moult at 15 °C and the 12th at 20 ° C. The intermoult period was shorter at the higher temperature and the growth rate higher. The moult increment was slightly larger at 15 °C, so following the puberty moult specimens were larger than at 20 °C, despite having had one fewer moult. The coefficient of variation in size did not increase through the sequence of larval instars but increased steadily through the postlarval sequence.

Studies on the pebble crab,Eriphia smithiMacLeay 1838 (Xanthoidea Menippidae): patterns of relative growth and population structure

Morphometry and population structure have been investigated in a large sample (about 800 specimens) of the tropical Xanthoidea Eriphia smithi MacLeay 1838 (Decapoda Brachyura), inhabiting a rocky cliff in Somalia. The analysis of relative growth in two sexual dimorphic characters (i.e., chelipeds and abdomen) showed that both sexes undergo the puberty molt at approximately 19 mm CL. However, functional maturity sensu HARTNOLL (1969) is attained only by larger instars. In the females, the ovaries begin to grow allometrically in weight with respect to animal weight at the size of 25 mm CL, when the ovigerous-ratio reached a constant value (about 42%) within the female population. Fecundity is size-dependent, the number of eggs per brood ranging from 14,000 in small ovigerous specimens to 60,000 in the largest ones. In the males, mating capability is limited not only by the developmental status of the gonads (gonad weight is inconsistent in individuals smaller than 25 mm CL), but also by the ownership of a copulatory burrow. The suitability of crevices for copulation depends on the presence of a narrow entrance (to prevent predation by fishes during high tides), and of an enlarged «nuptial» chamber. Due to their shape, these burrows are scarce within the cliff inhabited by this species, thus being a strong limiting factor for mating, and also requiring for their defence or conquest powerful weapons, i.e. long and wide chelipeds. Large males (>35 mm CL), which are both the best armoured (chelipeds exhibit in this sex a strong positive allometry), and the most fertile (gonopods grow allometrically in length, and the gonads in weight) are almost completely absent in the samples. It has been hypothesized that these individuals may increase their mating opportunity as owners of copulatory burrows where the largest females can be accomodated. Thus, a male has to fight with conspecifics of the same sex to defend or conquer a burrow, and/or, if resident, he never leaves his burrow undefended (i.e., he does not make long foraging excursions around the plateau). It is likely that either a high mortality (due to the frequent agonistic interactions) or a sedentary life-style could reduce the number of large males in our sample.

Contrôle endocrine et neuroendocrine de la mue de puberté chez les mâles de Sphaeroma serratum (Fabricius, 1787) (Crustacea, Isopoda, Flabellifera)

In the males of Sphaeroma serratum, the course of the puberty molt is controled by the Y organs, the brain, and perhaps the antennary glands. Y organs initiate and follow up proecdysis (probably by participating in production of ecdysterone, the physiological rate of which is high during D 0 and D 1) and secrete an ecdysis factor. After the puberty molt, they degenerate and the rate of ecdysterone reduces to zero. The brain initiates proecdysis, probably by secreting a Y-stimulating neurohormone (YSH), and in the control of ecdysis; it could stop in C 4 the molting cycle of adult males. The antennary glands control the mineral water metabolism and could act during the ecdysis, paticularly during the physiological ecdysis. These controls and their connections are discussed and a synthetic diagram is proposed.

La Dégénérescence De L'Organe y chez Sphaeroma Serratum (Fabricius, 1787) (Isopoda, Flabellifera): Étude Ultrastructurale

The Y organs of Sphaeroma serratum (females and non adult males) are glands of about 200 μm. Their cells show a large nucleus, and numerous mitochondria and free ribosomes. Golgi apparatus and endoplasmic reticulum are rare. At some intermolt stages cells with a different aspect appear. In the males of Sphaeroma, the degeneration of Y organs takes place after the puberty molt. It results in: (1) a reduced size of the nucleus, while the nucleoplasm becomes homogeneous, clear or (then ?) pycnotic, (2) the vacuolization of mitochondria, (3) the presence of vacuolar bodies, autophagic vacuoles and numerous clear vesicles. The cellular debris is perhaps removed by the hemocytes. The Y organs disappear entirely several weeks after the puberty molt.

Free amino acids of hemolymph during pubertal molting and senescence in Spaeroma serratum (Isopoda, Flabellifera

In Sphaeroma serratum, the amino-acidemia is high (about 120 mg/100 ml) during the intermolt stages. The relative proportions of the different free amino acids show only slight differences in young males and senescent ones. At the time of the puberty molt, the total amino-acids concentration (including taurine) of the hemolymph increases sharply during premolt (up to 267 mg/100 ml), falls after ecdysis (down to 97 mg/100 ml and then rises up to the level of the intermolt stage. These variations are due not only to concentration or dilution of the whole hemolymph constituents, but also to specific modifications of the concentration of some of the free amino-acids with respect to the others. These variations of the amino-acidemia, mainly those of serine, proline, glycine, alanine and of the amine taurine, could play a definite role in increasing the osmotic pressure of the hemolymph during premolt, as a preparation to ecdysis.