Successive Molts Research Articles

Growth of shrimps, crabs and lobsters - an assessment

Various highly significant linear correlations between the duration of the intermoult period and the growth factors at moulting on the one hand and body length, weight and successive moult number on the other are defined in decapod crustaceans. Log body weight or L3 is linearly related to log age. The presence of such correlations describing the growth and moulting in other groups of Crustacea is discussed. The application of the various regression equations to the study of growth and life histories of commercial species is described.

Laboratory growth of early juveniles of the western rock lobster Panulirus longipes cygnus

Growth in the laboratory of early juvenile Panulirus longipes cygnus George from the last larval (puerulus) stage to approximately 3 years of age is described. Specimens were held either in isolation or in groups of 3 or 5 rock lobsters per tank, at constant temperatures of 20° or 23°C (both ± 0.5 C°) or at the temperatures of the incoming seawater, which ranged annually between 14.9° and 25.9°C. Metamorphosis from the planktonic puerulus to the settled juvenile existence involved a reduction in size and usually took about two moults to complete. By this time the sexes could be distinguished. Growth in aquaria from the 2nd moult after puerulus until the juveniles were approximately 3 years of age was adequately described by exponential (von Bertalanffy) functions, with the growth curves gradually tapering off after the rock lobsters had reached 40 to 42 mm carapace length. Young juveniles were not gregarious until 20 to 25 mm carapace length (approximately 1.5 years old), however, growth rates were not depressed in individuals held in isolation up to approximately 3 years of age. Temperature markedly affected growth; the fastest observed growth up to 450 days was at 23°C. Variations in temperature resulted in decreased growth rates in “winter” and the reverse in “summer” in individuals at ambient temperatures. There was an increase in the moult increment at successive moults corresponding to increased carapace length, but increased growth rates were achieved through shortening the intermoult duration. The period of development from the puerulus stage until approximately 1.5 years of age is a distinct phase of development both of behaviour and growth.

Ecdysone and the super tick.

TICKS and insects develop and grow through intermittent replacement of their integument. This moulting does not occur beyond the adult stage, with the exception of primitive apterygote insects such as silverfish, which continue to moult and grow after they become sexually mature. Moulting ceases to occur in the pterygote adult insect because the glands secreting ecdysone, the hormone required to induce moulting, break down and disappear soon after the insect (and presumably also the tick) becomes adult1. The adult tissues of both hemimetabolous insects and those with complete metamorphosis continue to respond to ecdysone if exposed to it. There are, however, differences in the responsiveness of different segments of the insects and the resulting ‘super-moulted’ adult insects are usually defective2–5. We have found that ticks also retain the full potential to moult, grow and reproduce normally as adults if they receive ecdysone. Through successive adult moults ‘super ticks’ are obtained (Fig. 1) which consume very large volumes of blood and produce many more viable eggs than normal ticks.

The Hiatt growth diagram for crustacea

The Hiatt growth diagram relates post-moult to pre-moult size in crustaceans. Size in this context is most frequently defined by a linear measurement of length or width. Linear regression analysis of data on the Hiatt growth diagram is used to define growth constants. This assumes that growth factors (percentage increase in body size) at successive moults remain constant over the length of the line. Growth factors, however, decrease logarithmically at successive moults. Consequently, points on a Hiatt growth diagram are fitted better by a hyperbola than a straight line. The method of fitting an equation for a hyperbola is given. The best growth constant is the moult slope factor which is the factor by which the growth factor decreases at each successive moult. This is comparable with the intermoult period slope factor, the factor by which the intermoult period increases at each successive moult. These constants can be used to determine the moulting and growth sequences throughout the life of a crustacean.

The developmental cytology of the nuptial pad in the red-spotted newt

The ultrastructure of developing, mature and regressing nuptial pads has been examined and interpreted in the red-spotted newt. The development of the pad begins with a thickening of the dermis. Mitotic activity then increases the cell layers of the epidermis from about four to approximately eight. Simultaneously, keratinocytic synthetic activity shifts to produce more tonofilaments and fewer mucous granules. In the upper cell layers, the shift is followed by an increase in cytoplasmic volume with bundles of tonofilaments accumulating on the anterior side of each cell, displacing the nucleus posteriorly. After this rearrangement, the enlarged cells become grouped into ascending columns that tilt posteriorly from the basal epidermal layer at an angle of about 45°. Also the flattened cells of the monolayered stratum corneum become superficially roughened and with successive molts are replaced by orderly rows of cornified conical structures possessing cusps that are directed posteriorly. Each cone then lies at the top of one of the germinative columns. In rudimentary pads induced on female newts, the epidermis attains a height of only five or six layers and columns are not evident, but other developmental features of the male are present. During regression, mitosis is slowed and the developmental sequence is reversed.

LIMB LOSS AND THE MOLT CYCLE IN THE FRESHWATER SHRIMP,PALAEMONETES KADIAKENSIS

1. The loss of four walking legs induces molting in the freshwater shrimp, Palaemonetes kadiakensis. This study shows that at least in one species of Natantia, excessive limb loss accelerates the molting process as has been shown in several reptantian species.2. Removal of four appendages (two pairs of walking legs) during the four major stages of the molt cycle, A, B, C and D, produced varying results. When the appendages were removed during stage A or stage B of the intermolt cycle, the first molt following limb loss was accelerated. When limbs were removed during stage C of the molt cycle, two successive molts following limb loss were accelerated. Finally, when limb removal occurred during stage D of the intermolt cycle, the first postoperative molt was not affected, but the second postoperative intermolt cycle was shortened significantly.3. The sex of the organism did not affect the response to the loss of numerous appendages.4. Mortality rates due to the loss of four walking legs were negligible.5. A hypothesis was proposed to explain this molt-accelerating effect of limb loss.

ズワイガニに関する漁業生物学的研究-V

The integral temperature for the first zoeal molt of the tanner carb, Chionoecetes opilio, differs insignificantly between two cases, where, the larvae were transferred from hatching sea-water (specific gravity, 1.025) to rearing sea-water (sp. gr., 1.020-1.030) either directly or gradually. In rearing water with sp. gr. lower than 1.015, the direct transfer resulted in slightly longer time for the molt than did the gradual transfer. Survival rate of the first zoea stage was almost the same in both cases within a sp. gr. range of 1.015-1.030. Minimum time for molting was obtained at a sp. gr. range of 1.020-1.022 in the first and second zoea stages, and at a range of 1.020-1.024 in the megalopas. Thus, sp. gr. range for the most successful molting was considerably lower as compared with that of the water off Wakasa Bay. Over 70% of tested individuals in the first zoea stage were able to survive in a sp. gr. range of 1.022-1.027 and the range for similar survival in the second zoea stage was 1.019-1.026. Most of the first stage zoea reared at a sp.gr. of 1.012 failed to molt completely, and those which succeeded died within a few days.

The Molting Pattern in Trichinella spiralis. I. A Light Microscope Study

Development of Trichinella spiralis in rats was studied in detail to determine where and how many times the larvae molt. Four molts were observed during the intestinal phase of development, none earlier. In synchronously developing populations obtained by injecting excysted larvae directly into the duodenum, male worms molted at approximately 9, 13, 18, and 25 hr, females at approximately 10, 15, 21, and 28 hr, and inseminated females were first observed at 30 hr after inoculation. Each successive larval stage could be recognized by the thickness of the cast cuticle and the presence or absence of copulatory appendages, tuberculate papillae, and sperm in the male, and by the state of development of the vagina and uterus and the thickness and cross striations of the cuticle in the female. The development of T. spiralis can be divided into two periods, one in the tissues where, although there is no molt, the level of sexual differentiation reaches that of the fourth or early fifth-stage larva of phasmid nematodes, the other in the intestine where there are 5 stages, separated by 4 successive molts. The high level of sexual differentiation reached in the tissue phase of development together with the rapid succession of molts occurring in the intestine renders the Trichinella life cycle atypical among the trichuroids. Although more than a century has elapsed since the general life cycle of Trichinella spiralis (Owen, 1835) Railliet, 1895, was described by Leuckart and Virchow (Gould, 1945), its molting pattern is still disputed. It has been claimed that the first molt occurs within the egg in the uterus of the female, that there are two subsequent molts during the intramuscular phase, and one during the intestinal phase of development (Berntzen, 1965). It has also been reported that only two molts occur, both in the intestine (Podhajecky, 1964; Thomas, 1965; Shanta and Meerovitch, 1967a). One report (Kreis, 1937) suggested that males molt three times, females four times, but some observers have found that both males and females molt four times (Villella, 1958; Ali Khan, 1966). In vitro studies on the development of T. spiralis by Weller (1943) and by Tarakanov (1964) also suggested that the larvae of both Received for publication 2 March 1971. * Portion of a dissertation submitted to the Graduate School of Tulane University in partial fulfillment of the requirements for the degree of Doctor of Philosophy. This study was supported by grants AI-04919 and AI-00002 from the NIH, U. S. Public Health Service. Presented at the 44th Annual Meeting of American Society of Parasitologists, 6 November 1969, Washington, D.C. t Present address: Department of Microbiology, University of Chicago, 939 East 57th Street, Chicago, Illinois 60637. xes molt four times. Kim (1961, 1962) likew se proposed that four, or more, molts occurred in his in vitro system, but Meerovitch (1965) reported only two molts, and Berntz (1965) only one in their respective culture systems. Microand ultrastructural studies were conducted on stages of T. spiralis larvae from the female worms, and from the muscles and intestine of the host, in an attempt to determine how many molts occur during the development of this trichuroid, during which phases of the life cycle they occur, and what morphological characteristics can be used to differentiate the various larval stages. The present report is limited to the results obtained from the light microscopic studies. The ultrastruct-ural studies are presented separately (Kozek, 1971). MATERIALS AND METHODS Larvae were obtained from rats whose infections were 3 to 6 months old. Following a brief mincing in a Waring Blendor, the muscles were digested in 1% pepsin solution containing 1% HC1, for 2 to 6 hr at temperatures ranging between 37 and 40 C. Larvae were subsequently separated from tissue debris by sieving through a double layer of cheesecloth followed by sedimentation. The inoculating dose was administered to experimental[ animals in a 0.4or 0.5-ml volume of pepsin-muscle-digest fluid. The larvae and adult worms were observed alive, or after fixation with either Bles' fluid, AFA, 10% f rmalin, or 3% glutaraldehyde solution. The fixed worms were cleared in 70% ethanol + 5% glycerin mixture and mounted in glycerin.

Biochemical and physiological studies of certain ticks (Ixodoidea). Experimental feeding of Argas (Persicargas) arboreus Kaiser, Hoogstraal and Kohls (Argasidae) through membranes.

The best membrane and the optimum temperature for experimental feeding of ARGAS ( Persicargas ) Arboreus Kaiser, Hoogstraal, and Kohls proved to be Baudruche skin (commercially prepared from bovine intestine) at 38°C, a temperature within the normal range of the natural bird host of this tick species. Different blood components from herons, chickens, pigeons, and rabbits were offered to 2nd instar nymphs and to adults. Whole blood from birds was more efficient for the ticks' molting and oviposition than bird plasma or rabbits' whole blood, cells, or plasma. Contrary to usual findings in studies of bloodsucking insects, stretching of Arboreus nymphal integument during engorgement appears in itself not to release molting hormone. In this tick, the presence of a suitable nutrient, combined with the stretching effect of engorgement, apparently are important factors for successful molting.

Development of transitory piebald spotted and completely pigmented patterns in the chicken

At the time of hatching, pigment is restricted to black spots on a white background in the Ancona in comparison to the fully pigmented pattern of the Brown Leghorn, which serves as a standard of reference for feather coloration. During successive molts in the Ancona, the pigmented areas are extended until every feather follicle is producing pigment in the adult. Retarded migration of pigment cells is the simplest hypothesis that accounts for the development of the transitory piebald spotted pattern of the Ancona. That hypothesis was tested in the present investigation. Migration of melanoblasts in Ancona and Brown Leghorn embryos was traced at critical stages from stage 20 to time of hatching by transplanting blocks of tissue from different levels between the neural crest and the tip of the wing bud to White Leghorn host embryos. Results indicated that melanoblasts began to invade the wing buds of Brown Leghorn embryos at stage 21 and that all wing buds had received them by stage 23. Melanoblasts rarely invaded the distal 0.5 mm of the wing bud until after stage 32 in the Brown Leghorn. However, by stage 36 even the most distal primary follicle had received melanoblasts. Results for the Ancona were not as consistent. Although melanoblasts began entering the wing bud in stage 22, some of the wing buds still had not received them even by stage 24. Pigment cells apparently had not advanced beyond primary follicle no. 2 by stage 36 in the Ancona. Differentiated pigment granules and pigment deposits were observed in the skin overlying the mesencephalon of Ancona embryos at stages 20 and 23, respectively. There was no evidence of pigment granules or deposits in the same region of Brown Leghorn embryos at stage 23. Precocious differentiation and retarded proliferation of pigment cells appear to be correlated in the Ancona. At the time of hatching, the down and skin of the wing of the Ancona are pigmented in two spots, one having its center located on the dorsoposterior side near secondary follicle no. 8 and the other located just proximal to the base of digit II. In 8 cases where more than one graft was taken from individual Ancona wing buds, the results indicated that very few primordial melanoblasts migrated into the wing buds, possibly only one to the center of each spot. As a result of this study the following proposals are made. Each pigmented spot in the wing of the Ancona chick represents the settling point of a single primordial melanoblast from which pigment cells are proliferated. The same two settling points or centers may exist in fully pigmented as well as piebald spotted breeds. Early differentiation of melanoblasts may be the cause of slow proliferation and retarded migration of pigment cells from the centers in the Ancona, in comparison to normal differentiation, proliferation, and migration in the Brown Leghorn.

イノコステロン投与によるクルマエビの脱皮促進について

Recent finding and isolation of an insect molt-inducing hormone, the inokosterone, from the root of plants, Achyranthes, let the present author to carry out experiments to examine its effectiveness on crustaceans. The inokosterone solution was made up from 5.1mg crystal with 0.2ml of ethanol and 49.9ml of sterilized re-distilled water, and was injected into abdominal muscles of young P. japonicus (2.8-15.5g in body weight) by means of a tuberculin syringe at various time lapses after the first molt in the experimental aquaria. Molt inducing effect was examined by the length of time between the first and the second molt. A single injection of 0.03ml of the solution, which contained 3μg of inokosterone, per gram of live weight of the shrimp gave a remarkable molt-inducing effect. In the uninjected shrimps, or those injected with the comparable amount of sterilized re-distilled water (controls), intervals between molts varied from 9-16 days at the experimental temperature (25-27°C) depending on the body weight. Statistical treatment revealed that the interval between molts was increased by 0.8 day for every 1g increase in body weight. While, in the inokosterone injected shrimps intervals between molts no longer depended on body weight, but on the stage of molting cycle in which the inokosterone was injected. The intervals averaged 2.4 days for 6 shrimps which were injected on 0.5-1.5 days (stage B) after the first molt, and 7.0 days for 11 shrimps which were injected on 2.5-5.5 days (stage C) after the first molt. Thus the inokosterone injection during stages B or C markedly accerelated the molting cycle resulting in a precocious ecdysis on average of 3.3 days after the injection. When the shrimps were already in premolt condition (stage D) at the time of injection, molting occurred in less than 3 days (Fig. 3). Since the reaction time was too short to be in normal molting cycle it was postulated that the inokosterone may had a direct influence on the epidermis. Out of 29 inokosterone injected shrimps, 16 shrimps died during or just after the second molt. In 4 shrimps exuviations were incomplete, some parts of old exoskeleton, head or the posterior parts of abdomen, remained unmolted. Only 9 shrimps passed the successful second molt. While, in the controls as well as in uninjected shrimps second molts were always successful. Weight increases after the second molt were significantly less in the inokosterone injected shrimps, which had passed the successful molt, than in the controls or uninjected shrimps of comparable size.

The Intermolt Cycle of an Anomuran, Petrolisthes cinctipes Randall (Crustacea-Decapoda)

1. The intermolt cycle of Petrolisthes cinctipes is described and morphologic criteria are proposed for designating the physiologic stages of the cycle. The key for staging the animal is provided in Table I.2. The chronological changes in the derivation of new epidermis and bristles in the uropods furnish a reliable identification of the various stages even without recourse to palpation of the exoskeleton. The characteristics described by Drach (1939, 1944) and Scheer (1960) for certain species of crabs and prawns are found useful in staging a wide variety of Brachyura and Macrura; likewise, the diagnostic features in the stages of the porcellanid might be helpful in staging other Anomura as well.3. In the porcelain crab the duration between two successive molts is unusually long (about 115 to 130 days), especially in view of the small body size of the animal. This might mean that the growth rate of this crab is relatively higher. It would be equally interesting to know of a possible seasonal shortening or lengthening of the intermolt cycle (see Scheer, 1960) , the molting periodicity and the total number of molts the crab passes through before it enters the terminal anecdysis.

THE INTERMOLT CYCLE OF AN ANOMURAN, PETROLISTHES CINCTIPES RANDALL (CRUSTACEA-DECAPODA)

1. The intermolt cycle of Petrolisthes cinctipes is described and morphologic criteria are proposed for designating the physiologic stages of the cycle. The key for staging the animal is provided in Table I.2. The chronological changes in the derivation of new epidermis and bristles in the uropods furnish a reliable identification of the various stages even without recourse to palpation of the exoskeleton. The characteristics described by Drach (1939, 1944) and Scheer (1960) for certain species of crabs and prawns are found useful in staging a wide variety of Brachyura and Macrura; likewise, the diagnostic features in the stages of the porcellanid might be helpful in staging other Anomura as well.3. In the porcelain crab the duration between two successive molts is unusually long (about 115 to 130 days), especially in view of the small body size of the animal. This might mean that the growth rate of this crab is relatively higher. It would be equally interesting to know of a possible seasonal shortening o...

Optic Organs of Tribolium confusum and T. castaneum and Their Usefulness in Age Determination (Coleoptera: Tenebrionidae)

Two pairs of stemmata are present in all larval instars and in the early pupa of T. confusum Jacquelin du Val and T. castaneum (Herbst). They degenerate in the pupa as the compound eyes begin to develop. Larval instars are separable by determining the distance between the two pairs of stemmata. The stemmata are located near the antennae from the first throughout the early part of the last larval instar. With each successive moult the distance between the stemmata increases. During the latter part of the last larval instar, however, the interstemmatal distance decreases as the stemmata migrate to a position near the vertex. The degree of stemmatal migration can be used as an index for determining the ages of last larval instars. The orientation of the stemmata in the latter part of the last larval instar also differs from that seen in other instars. The pupal age can be estimated by counting the number of rows and considering the degree of development of the ommatidia of the compound eyes.

The Toxicities of Some Chlorinated Hydrocarbons to Various Larval Instars of the Army Cutworm in the Laboratory1

Of the chemicals tested as contact and as stomach poisons for the control of army cutworm, Chorizagrotis auxiliaris (Grote), endrin was the most toxic sixth-instar larvae and was equally effective as contact and as a stomach poison. The compounds appeared in the following order of toxicity: as contact poisons, endrin > dieldrin=aldrin=heptachlor >chlordane, and as stomach poisons, endrin = dieldrin >aldrin=heptachlor >chlordane. Fourth- to fifth-instar larvae were more readily killed by contact than sixth-instar larvae with each of the compounds. The susceptibiliy successive molts. Endrin was 35 times as toxic to fourth-instar 11 times as toxic to fifth-instar, and three times as toxic to freshly molted sixth-instar larvae as to mature feeding sixth instar cutworms.

Aging Meadow Mice, Microtus californicus, by Observation of Molt Progression

A distinct molt pattern in small rodents has been recognized by investigators for a number of years. Osgood (1909) described three color phases of Peromyscus as being due to difference in age but he did not correlate the three phases with specific ages. Collins (1918) found that the progression of molt pattern was consistent in P. gambeli as the animal's pelage changed from juvenile to post juvenile and found the change to occur between the 6th and 8th weeks of age. He points out that the molt may be well under way before it is evident at the hair surface. Coventry (1937) compared average sizes with the three principal color phases of P. leucopus noveboracensis and P. maniculatus gracilis . Pournelle (1952) correlated the “first molt” of P. g. gossypinus with age, Hatt (1931) gave a rough age-molt correlation in a captured flying squirrel, and Evans and Holdenried (1943) report that a molt starts in Citellus beecheyi soon after the young emerge from their burrows. Storer, et al. (1944) from observations of P. maniculatus describes ten stages of post juvenile molt, the entire molt requiring from eight to thirty-five days. For microtine rodents Hamilton (1938) described a definite molt pattern in captive Pitymys , the juvenile pelage lasting until about five weeks of age, after which the “adult” pelage first appeared on the sides. A complete change to adult pelage was noted at about seven weeks of age. Lavrov (1944) working in Russia, demonstrated two distinct molts in muskrats with a defined pattern in the first year of age and successive molts of no defined pattern occurring continuously thereafter. Kellogg (1946) noted the difference in primeness pattern on muskrat skins and suggested a possible age correlation. Applegate and Predmore (1947) and Shanks (1948), working independently but concurrently, demonstrated a …

The life-history of a brackish water amphipodGrandidierella bonnieri stebbing

The life-history of a brackish water amphipod,Grandidierella bonnieri Stebbing, is described from the successive moult stages. The actual process of moulting is described. The changes that takes place in antenna 1, the gnathopods, the uropods and the peraeopods, which have a very high taxonomic value, have been described in detail. The differentiation of features of antenna 1 during the growth has been illustrated and fully described.

Coloration Problems in Animals

ALL who are concerned with the problems raised by the coloration of animals will be interested in the announcement that two hog-deer (Cervus porcinus) have just been born at the Gardens of the Zoological Society of London. This animal, of about the size of a roe-deer, has a more or less conspicuously spotted coat in the summer, and one of a uniform brownish hue speckled with white in the winter. But the young are heavily spotted, as with our fallow and red-deer, the spots serving to form a ‘concealing’ coloration. Another coloration problem, and in a way yet more interesting, now presents itself in the sixteen flamingoes just purchased and sent to the Society's park at Whipsnade. These birds lose much of the brilliance of their pink coloration in captivity. Careful note should therefore be made of the intensity of pigmentation of the new arrivals. It has been stated that birds in the London Gardens recovered their lost brilliance when they were turned out into a paddock affording free access to a large pond, well-stocked with small crustaceans. In the gardens of the New York Zoological Society an interesting experiment was made, years ago, on the beautiful rosy flamingo (Phœnicopterus ruber) which, in successive moults during captivity, became paler and paler, and finally almost white. By mixing a harmless dye with the food the fading process was considerably lessened, while some retained their original full colour for years. What was the ‘harmless dye’, and was it continuously administered? Under the more favourable conditions at Whipsnade, perhaps these birds may breed. In this event a valuable opportunity will be furnished to mark the effect, if any, of climatic influence, and food, on the coloration in their progeny.

Studies in intersexuality.—II. Sex-reversal in the fowl

Many instances of “hermaphroditism” and of the more or less complete assumption of the secondary sexual characters of the male by the old female bird, wild and domesticated, have been recorded, but in the great majority of such cases no accurate knowledge of the previous history of the individual has been available and each has been considered as an isolated case. It was thought that a study of these conditions as met with in the domestic fowl would be of genetic interest. In order to obtain specimens and information the poultry keepers of the country were circularised. It was found that:— (1) Rare cases of “hermaphroditism” have been encountered. A bird at the age of 4—6 months, instead of developing the distinctive male or female characters, grows slowly into a creature which is neither a pullet nor a cockerel and its characters remain indefinitely intermediate. (2) Rare cases are known of an otherwise perfectly normal laying hen with cocky plumage. In one such case, known to the present writer, the plumage following successive moults has been cocky—henny—cocky.