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Journal ArticleDOI

Yolk utilization and hatching time in the Canadian lobster Homarus americanus

01 Nov 1970-Marine Biology (Springer Berlin Heidelberg)-Vol. 7, Iss: 3, pp 249-254
TL;DR: During the course of its embryonic development, the Canadian lobster Homarus americanusMilne-Edwards exhibits steady increases in water content and ash and a progressive decrease in energy content from 6636 to 4292 cal/g dry weight.
Abstract: During the course of its embryonic development, the Canadian lobster Homarus americanusMilne-Edwards exhibits steady increases in water content (56.2 to 86.8%) and ash (5.8 to 21.2%), and a progressive decrease in energy content from 6636 to 4292 cal/g dry weight. Mean dry weight of a single egg is 965 μg, equivalent to 6.4 cal; a freshly hatched egg. The lobster hatches about 1,500 larvae per night over a period of 4 to 5 days. Dry weight, ash and calorific contents of larvae hatched on different days show considerable variations. After larvae hatch on the first day, continuous salt absorption by eggs to hatch on subsequent days leads to a steady increase in ash content from 143 μg/larva hatched on the first day to 255 μg/larva hatched on the fourth day, and consequently, to an increase in dry weight from 854 to 956 μg/larva. Metabolism of embryos (0.1 cal/day), which are yet to be hatched on subsequent days, depletes the calorific content per unit weight (from 4637 to 3837 cal/g dry weight) as well as per larva (from 3.98 to 3.67 cal).

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Citations
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Journal ArticleDOI
TL;DR: The imbibition of water by the developing marine demersal egg seems to serve in osmotic hatching; float the hatched larva by means of specific gravity reduction; and aid the larva to quickly adjust its body temperature in the light of Needham's concept of “cleidoicterrestrial and non cleidoic-aquatic eggs”.
Abstract: During the course of its embryonic development, the European lobster Homarus gammarusLinnaeus exhibits progressive increases in content of water (54.0 to 83.1%), ash (2.7 to 16.7%), protein (47.4 to 50.9%) and non-protein nitrogen (1.0 to 2.4%), and steady decreases in content of fat (43.8 to 25.4%) and energy (6343 to 5431 cal/g dry organic substance). Cumulative yolk utilization efficiency during the total development is 81.8% for dry weight; the corresponding value for energy is 60.1, for protein 75.6 and for fat 47.4%. Energy content of a single egg is 10.49 cal. Of 4.20 cal expended for metabolic processes of the embryo, only 13.3% energy is drawn from protein oxidation; fat oxidation supplies as much as 87.7% energy, that of carbohydrate only 2.3%. Embryonic development results in a remarkable decrease in net yolk utilization efficiency, which falls from 85.5% in the early developmental stages, to less than 70% in later developmental stages. The mean dry weight of a single egg membrane increases from 38 μg (2.2% of egg weight) in a freshly laid and attached egg, to 81 μg in an egg with an almost completely developed embryo. This result supports the earlier observation of Cheung (1966) that the formation of the inner chitinous egg membrane occurs after the egg is laid and attached to the setum. Protein seems to be the major constituent of the egg membrane (4049 cal/g dry weight), which has the following composition: protein 70.4%, non-protein nitrogen 0.13%, ash 2.83%. Initial permeability of the egg membrane to water (about 6% of the total water requirement is let in) is followed by a period during which the egg membrane is almost impermeable to water (stages I to III); the egg membrane becomes permeable to water again and lets in 85% of the total water requirement (the rest, i.e. 9%, is metabolic water) at a relatively advanced stage of development. These assumed changes in egg membrane permeability appear to be indicative of variations in the egg's osmoconcentration leading to shiftings in net transport of water. Rates of water and salt uptake during embryonic development are essentially parallel (Fig. 1). The egg membrane remains permeable to salts throughout development; salt intake almost doubles after the egg passes through stage III. A single egg, weighing 3.7 mg requires 4.9 mg water for successful completion of embryonic development. The imbibition of water by the developing marine demersal egg seems to (1) serve in osmotic hatching; (2) float the hatched larva by means of specific gravity reduction; (3) aid the larva to quickly adjust its body temperature. The simple osmotic hatching mechanism, proposed by previous workers, seems to be inadequate to account for the events and timing of the hatching process in the lobster. It is suggested that hatching time is determined not solely by increased internal pressure caused by inflow of water and salts, but also by some unknown internal factor. In the lobster egg, as well as in many other marine demersal eggs, protein metabolism is suppressed to a considerable extent, and fat metabolism is “geared up” Thus, the non-cleidoic lobster eggs exhibit metablic properties which are typical of cleidoic eggs. This finding is discussed in the light of Needham's (1950) concept of “cleidoicterrestrial and non cleidoic-aquatic eggs”.

166 citations

Journal ArticleDOI
TL;DR: The quantitative staging of lobster development from extrusion to hatching, and the description of the embryonic molt cycle will facilitate future investigations on particular aspects of the embryogenesis of Homarus such as neural differentiation.
Abstract: The growth of a single brood of lobsters (Homarus americanus Milne-Edwards 1837) maintained at constant temperature is studied from the naupliar stage to hatching, and the sequence of appearance of morphological, anatomical, and behavioral characteristics observed. A percent-staging system based upon Perkins' eye index (1972) is presented, and ten equally spaced embryonic stages are illustrated and characterized at different levels of resolution: whole eggs, dissected embryos, antennulae and telsons. The tegumentary and setal changes in the telson show that a complete molt cycle takes place in the egg starting at about 12% embryonic development (E12%) with the molt of the nauplius into the metanauplius and ending just after hatching when the metanauplius molts into a first stage larva (L1, first zoea). At E30%, the cuticle begins to separate from the setae in the telson; this signals the start of Drach's (1939) stage D0 of the metanaupliar embryonic molt cycle. At that time, the first sign of organogenesi...

138 citations

Journal ArticleDOI
TL;DR: An integrated series of events links the appearance of osmoregulatory tissues, the increase in Na(+)/K(+)-ATPase activity, the occurrence in postlarvae of hyper-regulation at low salinity and the increase of salinity tolerance in lobsters.
Abstract: Adaptations to salinity are reviewed throughout development in both species of the genus Homarus. Some populations of homarid lobsters are known to inhabit coastal and estuarine areas where salinity fluctuates. Salinity tolerance varies during development, with 50 % lethal salinities (LS(50)) ranging from approximately 15–17 in larvae to approximately 12 in postlarvae and 10 in adults. Larval and adult lobsters can avoid low-salinity areas using behavioural strategies. When exposed to low salinity, the capacity to osmoregulate varies with development. Embryos are osmoconformers and are osmotically protected by the egg membranes. Larvae are also osmoconformers, and the pattern of osmoregulation changes at metamorphosis to hyper-regulation, which is retained throughout the later stages up to the adult stage. Exposure to low salinity increases the activity of Na(+)/K(+)-ATPase in postlarvae and later stages. The level of osmoregulation evaluated through the osmoregulatory capacity (the difference between haemolymph and medium osmolalities) is negatively affected by low temperature (2 degrees C). The variations in haemolymph osmolality resulting from osmoconforming or partial osmoregulation are compensated by intracellular iso-osmotic regulation. Neuroendocrine control of osmoregulation appears in postlarvae and seems to involve the crustacean hyperglycaemic hormone. In adult lobsters, the gills appear to have a respiratory function only, and extracellular osmoregulation is effected by the epipodites, with the addition of the branchiostegites at low salinity. These organs are present at hatching. Transmission electron microscopy and immunolocalization of Na(+)/K(+)-ATPase reveal that the epipodites become functional in larvae and that the branchiostegites become functional in postlarvae. An integrated series of events links the appearance of osmoregulatory tissues, the increase in Na(+)/K(+)-ATPase activity, the occurrence in postlarvae of hyper-regulation at low salinity and the increase in salinity tolerance. Further ecological and physiological studies are proposed for a better understanding of the adaptive significance of the ontogeny of osmoregulation in lobsters.

86 citations


Cites background from "Yolk utilization and hatching time ..."

  • ...It has been suggetsed that the permeability increases in lobster eggs before hatching which, given their high internal osmolality, would result in osmotic intake of water and subsequent rupture of the membranes (Pandian, 1970a,b)....

    [...]

Journal ArticleDOI
TL;DR: Differences in the reproductive variables and investment between the two broods of C. crangon are discussed in the light of reproductive strategies and life history.
Abstract: Aspects of the reproductive biology of the common shrimp Crangon crangon (L.) were studied in Port Erin Bay, Isle of Man, Irish Sea. Size at sexual maturity was determined from the proportions of ovigerous females and of females with maturing ovaries. The size at which 50% of females are mature is estimated (±95% confidence intervals) as 12.5±0.48 mm carapace length. Based on the proportions of ovigerous females and of mature females, the main breeding season was from January to June. Mean ovarian dry weights indicated two broods (winter and summer), with females bearing winter broods (WB) having higher gonad indices than those with summer broods (SB). WB females with non-eyed eggs and with eyed eggs differed in the regression of ovarian dry weight on carapace length, indicating preparation for laying a second brood. In both broods the moult stages of berried females were related to egg stage. Moulting will occur following the release of the brood. During embryonic development, mean egg length and egg volume were larger in all stages, and the mean dry weight of individual eggs of all stages heavier, in WB than in SB; there was no difference in egg number, however. Consequently, reproductive investment, the proportion of female weight devoted to egg production, was 67% higher in WB (0.20±0.04) than in SB (0.12±0.03). There is a significant effect of egg volume on brood weight, but not on egg number. In both broods, egg number was a negatively allometric function of female body size in non-eyed eggs and an isometric function of female body size in eyed eggs. Brood mortality during incubation was higher in SB (17%) than WB (10%). Differences in the reproductive variables and investment between the two broods of C. crangon are discussed in the light of reproductive strategies and life history.

78 citations


Cites background from "Yolk utilization and hatching time ..."

  • ...This was due to an increased water content and changes in the biochemical composition during embryonic development ( Pandian 1967, 1970a, b; Davis 1968; Subramonian 1991; Clarke 1993a)....

    [...]

01 Jan 1982
TL;DR: In all larval stages, weight-specific energy (Jfmg DW) follows rather a cyclic pattern with decreases before and after molts, and increases during intermolt periods, and shows a decreasing trend during larval development.
Abstract: Laboratory-reared larvae of the spider crab, Hyas araneU8 L., were studied with regard to their fresh weight (FW), dry weight (DW), carbon (C), nitrogen (N), hydrogen (H), and energycontent(J; estimated from C). FW remains fairly constant in each larval stage, regardless of feeding or starving conditions. This is due to regular changes in water content as opposed to those in organic constitutents. FW therefore is not a good measure for living biomass. Growth in fed zoeal stages, if expressed by gain in any parameter but FW, can be described by power functions oftime. There is a considerable gain (by a factor of 2 to 3) within each of these two instars. In the magalopa also a high amountof C, N, H, andenergy is accumulated, but most ofthis gain is lost again during the last third of its stage duration. This finding suggests that there is no more food uptake during this last period preceding metamorphosis to the crab. In all larval stages, weight-specific energy (Jfmg DW) follows rather a cyclic pattern with decreases before and after molts, and increases during intermolt periods. It shows a decreasing trend during larval development. The loss in cast exoskeletons is 30% in the megalopa. During starvation, biomass declines in an exponential pattern. Larvae of all stages die, when ca. 40 to 60% oftheir living substance and energy is lost. TheC:N ratio suggests that protein serves as the mainsource of energy; in the final phase, presumbaly, lipids are also catabolized. Weight-specific energyand probably also metabolism decrease in a hyperbola-shaped curve.

71 citations

References
More filters
Journal ArticleDOI
TL;DR: The imbibition of water by the developing marine demersal egg seems to serve in osmotic hatching; float the hatched larva by means of specific gravity reduction; and aid the larva to quickly adjust its body temperature in the light of Needham's concept of “cleidoicterrestrial and non cleidoic-aquatic eggs”.
Abstract: During the course of its embryonic development, the European lobster Homarus gammarusLinnaeus exhibits progressive increases in content of water (54.0 to 83.1%), ash (2.7 to 16.7%), protein (47.4 to 50.9%) and non-protein nitrogen (1.0 to 2.4%), and steady decreases in content of fat (43.8 to 25.4%) and energy (6343 to 5431 cal/g dry organic substance). Cumulative yolk utilization efficiency during the total development is 81.8% for dry weight; the corresponding value for energy is 60.1, for protein 75.6 and for fat 47.4%. Energy content of a single egg is 10.49 cal. Of 4.20 cal expended for metabolic processes of the embryo, only 13.3% energy is drawn from protein oxidation; fat oxidation supplies as much as 87.7% energy, that of carbohydrate only 2.3%. Embryonic development results in a remarkable decrease in net yolk utilization efficiency, which falls from 85.5% in the early developmental stages, to less than 70% in later developmental stages. The mean dry weight of a single egg membrane increases from 38 μg (2.2% of egg weight) in a freshly laid and attached egg, to 81 μg in an egg with an almost completely developed embryo. This result supports the earlier observation of Cheung (1966) that the formation of the inner chitinous egg membrane occurs after the egg is laid and attached to the setum. Protein seems to be the major constituent of the egg membrane (4049 cal/g dry weight), which has the following composition: protein 70.4%, non-protein nitrogen 0.13%, ash 2.83%. Initial permeability of the egg membrane to water (about 6% of the total water requirement is let in) is followed by a period during which the egg membrane is almost impermeable to water (stages I to III); the egg membrane becomes permeable to water again and lets in 85% of the total water requirement (the rest, i.e. 9%, is metabolic water) at a relatively advanced stage of development. These assumed changes in egg membrane permeability appear to be indicative of variations in the egg's osmoconcentration leading to shiftings in net transport of water. Rates of water and salt uptake during embryonic development are essentially parallel (Fig. 1). The egg membrane remains permeable to salts throughout development; salt intake almost doubles after the egg passes through stage III. A single egg, weighing 3.7 mg requires 4.9 mg water for successful completion of embryonic development. The imbibition of water by the developing marine demersal egg seems to (1) serve in osmotic hatching; (2) float the hatched larva by means of specific gravity reduction; (3) aid the larva to quickly adjust its body temperature. The simple osmotic hatching mechanism, proposed by previous workers, seems to be inadequate to account for the events and timing of the hatching process in the lobster. It is suggested that hatching time is determined not solely by increased internal pressure caused by inflow of water and salts, but also by some unknown internal factor. In the lobster egg, as well as in many other marine demersal eggs, protein metabolism is suppressed to a considerable extent, and fat metabolism is “geared up” Thus, the non-cleidoic lobster eggs exhibit metablic properties which are typical of cleidoic eggs. This finding is discussed in the light of Needham's (1950) concept of “cleidoicterrestrial and non cleidoic-aquatic eggs”.

166 citations

Journal ArticleDOI
01 Nov 1967
TL;DR: The cumulative efficiencies of yolk utilization for different constituents varied; they were 703% for dry weight, 540% for total energy, 830% for protein, and 336% for fat.
Abstract: 1 Changes in chemical composition and caloric content as well as the cumulative efficiencies of yolk utilization have been studied in the developing eggs and freshly hatched protozoea of the shrimpCrangon crangon L 2 Per unit dry weight of the fresh egg the following relative increases were observed during the development: 168% water, 59% ash, 106% protein, and 05% non-protein nitrogen During the same period (fresh egg to freshly hatched protozoea) fat content decreased from 326% to 156% and energy content from 6443 to 5287 cal/g dry organic substance 3 The cumulative efficiencies of yolk utilization for the different constituents varied; they were 703% for dry weight, 540% for total energy, 830% for protein, and 336% for fat 4 Of the 00453 cal expended on the metabolic processes of the embryo, only 208% was drawn from the oxidation of protein, while fat oxidation contributed as much as 750% 5 Considerable quantities of inorganic salts (029µg/egg) were absorbed from the surrounding sea-water by the egg during its development

72 citations

Journal ArticleDOI
TL;DR: The biochemical composition of the eggs of Balanus balanoides and B. balanus has been determined during development as discussed by the authors, showing that the pigment is largely a chromolipid; during the early stages of development this increases, but is subsequently lost.
Abstract: The biochemical composition–water, glucose, soluble and insoluble glycogen, protein and non-protein nitrogen, total lipid–of the eggs of Balanus balanoides and B. balanus has been determined during development.Preliminary analyses of the pigment content are reported.The changes in both species are similar; but they take place more rapidly in B. balanus with its shorter period of embryonic development.During development there is a net loss of all fractions; small increases of glucose and soluble nitrogen are, however, found at certain stages.The pigment is largely a chromolipid; during the early stages of development this increases, but is subsequently lost; astaxanthin is also present. The visual appearance is a poor guide to pigment content.The oxygen uptake of the eggs has been measured.There is a discrepancy between the oxygen uptake measured directly and that required to oxidize the substrate lost; the causes of this are discussed.The results are discussed relative to the habitats of the species.

56 citations

Journal ArticleDOI
01 Nov 1967
TL;DR: The chemical composition and caloric content of egg and zoea of the hermit crab and Eupagurus bernhardus have been determined and the cumulative efficiencies of yolk utilization calculated.
Abstract: 1. Chemical composition and caloric content of egg and zoea of the hermit crabEupagurus bernhardus have been determined and the cumulative efficiencies of yolk utilization calculated. 2. The cumulative efficiencies of yolk utilization for different constituents were 70.0%, 55.3%, 79.4% or 35.0% for dry weight, caloric content, protein or fat. 3. Since the efficiencies with which the different constituents of yolk utilized vary, the chemical composition of the developing eggs undergoes considerable changes. While fat and caloric content showed remarkable decreases, water, ash and protein contents of the eggs increased. 4. Of 0.0722 cal expended on metabolic processes of the embryo, only 28.4% was drawn from the oxidation of protein, while fat contributed as much as 66.6%. 5. Considerable quantities of inorganic salts (0.77µg/egg) are absorbed from the sea-water by the developing egg.

52 citations

Journal ArticleDOI
TL;DR: The increases in constituents per unit weight of eggs during embryonic development of the gastropod Crepidula fornicata amounted to 14.6% for ash, 1.0% for protein, and 0.3% for non-protein nitrogen.
Abstract: The increases in constituents per unit weight of eggs during embryonic development of the gastropod Crepidula fornicata amounted to 14.6% for ash, 1.0% for protein, and 0.3% for non-protein nitrogen. During the same stages, fat content decreased from 33.7 to 20.3%, carbohydrate from 10.2 to 7.7% and energy content from 6209 to 5298 cal/g dry organic substance. The cumulative efficiencies for yolk utilization were 83.8% for dry weight, 61.0% for energy, 85.1% for protein, 50.7% for fat, and 63.6% for carbohydrate. A single egg contained 0.0269 cal, a single veliger 0.0164 cal. Of the 0.0105 cal expended on metabolic processes of the embryo, oxidation of fat contributed as much as 65.3%, while that of protein and carbohydrate amounted only to 18.8 and 6.3%, respectively. On the basis of ecophysiological considerations, a new classification of eggs is proposed.

38 citations