Embryonic and intracapsular larval development of Plicopurpura pansa (Gould, 1853) (Prosobranchia, Muricidae) under laboratory conditions (original) (raw)
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Plasticity of Hatching and the Duration of Planktonic Development in Marine Invertebrates
Integrative and Comparative Biology, 2011
Synopsis Plasticity in hatching potentially adjusts risks of benthic and planktonic development for benthic marine invertebrates. The proportionate effect of hatching plasticity on duration of larval swimming is greatest for animals that can potentially brood or encapsulate offspring until hatching near metamorphic competence. As an example, early hatching of the nudibranch mollusk Phestilla sibogae is stimulated by scattering of encapsulated offspring, as by a predator feeding on the gelatinous egg ribbon. When egg ribbons are undisturbed, hatching is at or near metamorphic competence. Disturbance of an unguarded benthic egg mass can insert 4 or more days of obligate larval dispersal into the life history. As another example, the spionid annelid Boccardia proboscidea broods capsules, each with both cannibalistic and developmentally arrested planktivorous siblings plus nurse eggs. Early hatching produces mainly planktivorous larvae with a planktonic duration of 15 days. Late hatching produces mainly adelphophages who have eaten their planktivorous siblings and metamorphose with little or no period of swimming. Mothers actively hatch their offspring by tearing the capsules, and appeared to time hatching in response to their environment and not to the stage of development of their offspring. Higher temperature increased the variance of brooding time. Females appeared to hatch capsules at an earlier developmental stage at lower temperatures. Species that release gametes or zygotes directly into the plankton have less scope for plasticity in stage at hatching. Their embryos develop singly with little protection and hatch at early stages, often as blastulae or gastrulae. Time of hatching cannot be greatly advanced, and sensory capabilities of blastulae may be limited.
Embryonic and larval development of spotted murrel, Channa punctatus (Bloch)
2003
Induced breeding experiments of spotted murrel, Channa punctatus (Bloch) were conducted in mature males and females by administrating a single intramuscular injection of ovaprim at a dosage of 0.3ml/Kg body weight. Spawning was observed 23-24 hrs after the injection at ambient temperature and the fertilized eggs were buoyant, non-adhesive, and straw yellow in colour with diameter ranging between 0.9mm and1.10 mm. Incubation period was 24-25 hrs. The hatchlings were transparent and measured 2.7-2.9mm, with a large oval head, a well-defined yolk sac and short tail and the larvae attained free normal movement when 36 hrs old. The yolk got fully absorbed within 3 days and by this time mouth formation was complete and the larvae started feeding. The post larvae were observed to start aerial respiration on 17 th day. After 20 days the length of fry ranged between 7.5 and 7.8mm and resembled the adult in its external features. Length of the fingerlings ranged from 18.3-21.0mm after 35 days and appeared just like an adult in all respects except sexual maturity.
Due to its high taste value and large size (the biggest among pectinids), Mizuhopecten yessoensis has become a very popular food product and is used as an object of aquaculture in a number of countries. In spite of the high economic value of this scallop, no ultramicroscopic studies of embryonic and larval stages of its development have been carried out to date. At a water temperature of 13°C, gastrulae of M. yessoensis are formed within 24 hours after fertilization. They are rounded, oval, or tapered in shape and have two invaginations: the primordium of shell gland is located on the dorsal side, and the blastopore is on the ventral side. In the shell gland primordium, there are cells that begin differentiating to secrete the larval shell subsequently. Embryos are composed of cells morphologically similar to each other. Their cytoplasm contains yolk granules of two types: with a lipoprotein and glycoprotein content. Within 51 hours of development, most embryos are represented by trochophores. The apical plate of these larvae is fringed by the locomotor organ, prototroch, formed by a double ring of cilia. There is long ciliary tuft of the apical flagellum, formed by a group of associated cilia, at the centre of apical plate. The cells of archenterone and the external wall of the larva body are still morphologically similar to each other at this stage. In the primary cavity of the body, a pool of undifferentiated mesenchymal cells is observed. Within 70 hours of development, most larvae become late trochophores. The growth of the prodissoconch I is active; prototroch gradually transforms into velum. Synthetic processes are activated in cells of the larval gut. The myogenic differentiation of mesodermal myoblasts begins. On day 8 of development, all larvae are represented by early veligers. Their body is covered with a semitranslucent shell. The apical plate of larvae is edged with locomotor organ, velum. The anterior adductor is still undeveloped at this stage. The larval velar retractor muscles have cross striation with a period of 1 μm. The larval intestine is well differentiated. It consists of esophagus, stomach, and short gut opening into the mantle cavity. The esophagus wall is formed by ciliated epithelium. The stomach wall, in spite of the early stage of development, already shows a clear division into regions corresponding to the gastric shield and style sac of adult animal. The digestive gland at this stage is a swelling of the stomach wall, without forming the lobes. It is formed by cells of two types: undifferentiated cells, division of which provides the growth of organ, and cells that perform the intracellular digestion processes. Thus, we have studied the structure of embryonic and early larval stages of M. yessoensis development, using SEM and TEM, for the first time.
Embryonic and larval development of Pinctada margaritifera (Linnaeus, 1758)
Molluscan Research, 2003
We describe the developmental stages of the black-lip pearl oyster, Pinctada margaritifera (Linnaeus, 1758), larvae from fertilisation through embryonic development and larval growth in the laboratory at 28 ± 1°C. Larvae were anesthetised, fixed, critical-point dried and examined using a scanning electron microscope. We examined embryonic development (fertilisation, polar body, blastomeres, gastrula) and attributes of the larval shell (size, prodissoconch I/II, growth lines, provinculum, shell fracture) and larval velum. The first polar body formed 24 min after fertilisation and fertilised eggs had a mean diameter of 59.9 ± 1.4 µm. The earliest actively swimming trochophore appeared 8-12 h after fertilisation. The D stage was reached approximately 24 h after fertilisation and measured 79.7 ± 2.3 µm in shell length. Ten-day-old larvae had umbones that arose opposite each other above the hinge axis and 22-day-old larvae, with a mean shell length of 230.8 ± 4.9 µm, developed a pigment spot just before entering the pediveliger stage.
Journal of the Marine Biological Association of the UK, 2006
Spawn and the embryonic development of two species of the genus Polycera were studied. Both species, Polycera aurantiomarginata and Polycera quadrilineata, were collected in the intertidal zone of El Portil (Huelva) in south-western Spain. In the laboratory spawn were collected daily. Length and width of the spawn, number of eggs per mm2, egg size and capsule size were measured. The egg masses were controlled several times a day to provide a timetable for the main developmental events until hatching. Embryonic growth was measured between some characteristic stages (gastrula, preveliger, primordial velum and veliger prior to hatch).The two species differ in a number of aspects: spawn are longer, eggs and capsules are bigger in P. aurantiomarginata than in P. quadrilineata. The number of eggs per mm2, however, is greater in P. quadrilineata than in its congener. Furthermore, spawn of P. quadrilineata are semicircular whereas those of P. aurantiomarginata are spiral and wavy. Both spec...
Journal of Experimental …, 2007
The larval development of the squat lobster Munida subrugosa from subantarctic waters of the Beagle Channel (Tierra del Fuego, Argentina) was studied under controlled laboratory conditions of temperature, salinity, and food supply. Developmental times, survival, and growth of larvae and early juveniles were investigated. Hatching of the entire brood always occurred during one night. Larvae were kept in 100ml individual bowls with filtered seawater at 8 ± 0.5°C and fed with Artemia spp. nauplii three times a week. Larvae passed through 6 zoeal instars and one megalopa. Previously, only five zoeal instars were known from this species. Mean cumulative durations of the zoeal stages I to VI were: 20.5 ± 2.5, 33.9 ± 4.1, 43.3 ± 5.4, 52.6 ± 5, 61.2 ± 3.9, and 83days, respectively. By adding the 28days that a single megalopa took to metamorphose to crab I stage, the complete larval development lasted 111days. Highest mortality occurred prior to the moult from the zoea I to zoea II stage (79.21% ± 18.65%) and during the moult from zoea VI to megalopa (92.86%). Carapace length was 1.64 ± 0.06, 1.52 ± 0.16, 1.57 ± 0.26, 1.64 ± 0.21, 2.11 ± 0.35, and 2.58 ± 0.19mm, for zoeal stages I to VI, respectively. Carapace length of megalopae and crab I instars was similar (2.85 ± 0.28 and the 2.84 ± 0.05, respectively). Unlike other subantarctic decapods, which show a tendency towards abbreviated larval development and/or some degree of endotrophy, M. subrugosa shows an extended planktotrophic larval development synchronized with short seasonal plankton production in austral summers.
Helgoland Marine Research, 2013
This study provides the first description of the larval development of the commercially exploited barnacle Megabalanus azoricus. It describes the changes in larval size and shape as well as the general morphology and duration of each larval stage. Embryos were obtained from gravid specimens collected at São Miguel Island and reared through six naupliar stages to the cypris stage in laboratory conditions. The planktotrophic nauplii reached the cypris stage after 14 days of hatching in individual cultures at 20 °C under natural illumination and fed with phytoplankton (Chaetoceros gracilis, Isochrysis sp., and Tetraselmis sp.). The nauplius of M. azoricus has a normal size compared with nauplii of other congeneric species, ranging between the 261 μm (nauplius I) and 912 μm (nauplius VI). This work provides the first description of larvae of the genus Megabalanus for the Portuguese oceanic islands and provides comparisons with congeneric species in other parts of the world.