Malacostracan Crustacea Research Articles

Immunolocalization of histamine in the optic neuropils of Scutigera coleoptrata (Myriapoda: Chilopoda) reveals the basal organization of visual systems in Mandibulata

Myriapods play a crucial role in considerations of evolutionary transformations of arthropod nervous systems. The existing descriptions of the identity and connectivity of myriapod optic neuropils are contradictory. This study asks if the first and second optic neuropil of the scutigeromorph centipede Scutigera coleoptrata correspond to the optic neuropils of Hexapoda and malacostracan Crustacea, the lamina and medulla which are linked by neurites that are arranged in a characteristic optic chiasm. To identify photoreceptor axons, we used immunohistochemistry against histamine which is the universal transmitter of arthropod photoreceptors. Our results provide evidence that the two optic neuropils of S. coleoptrata correspond to the lamina and medulla of Hexapoda and Malacostraca and strongly argue against a correspondence of the optic neuropils in branchiopod crustaceans and scutigeromorphs, as was previously suggested. We conclude that these two retinotopic optic neuropils and an outer optic chiasm are part of the ground pattern of Mandibulata and that the visual systems of branchiopod crustaceans were simplified from this ground pattern.

Organization of Deutocerebral Neuropils and Olfactory Behavior in the Centipede Scutigera coleoptrata (Linnaeus, 1758) (Myriapoda: Chilopoda)

Myriapods represent an arthropod lineage, that originating from a marine arthropod ancestor most likely conquered land independently from hexapods and crustaceans. Establishing aerial olfaction during a transition from the ocean to land requires molecules to be detected in gas phase instead of in water solution. Considering that the olfactory sense of myriapods has evolved independently from that in hexapods and crustaceans, the question arises if and how myriapods have solved the tasks of odor detection and odor information processing in air. Comparative studies between arthropod taxa that independently have established a terrestrial life style provide a powerful means of investigating the evolution of chemosensory adaptations in this environment and to understand how the arthropod nervous system evolved in response to new environmental and ecological challenges. In general, the neuroethology of myriapods and the architecture of their central nervous systems are insufficiently understood. In a set of experiments with the centipede Scutigera coleoptrata, we analyzed the central olfactory pathway with serial semi-thin sectioning combined with 3-dimensional reconstruction, antennal backfilling with neuronal tracers, and immunofluorescence combined with confocal laser-scanning microscopy. Furthermore, we conducted behavioral experiments to find out if these animals react to airborne stimuli. Our results show that the primary olfactory and mechanosensory centers are well developed in these organisms but that the shape of the olfactory neuropils in S. coleoptrata is strikingly different when compared with those of hexapods and malacostracan crustaceans. Nevertheless, the presence of distinct neuropils for chemosensory and mechanosensory qualities in S. coleoptrata, malacostracan Crustacea, and Hexapoda could indicate a common architectural principle within the Mandibulata. Furthermore, behavioral experiments indicate that S. coleoptrata is able to perceive airborne stimuli, both from live prey and from a chemical extract of the prey. These results are in line with the morphological findings concerning the well-developed olfactory centers in the deutocerebrum of this species.

The importance of lithographic limestones for revealing ontogenies in fossil crustaceans

Developmental biology has become a major issue for understanding the evolution of Arthropoda. While usually only the ontogenies of extant species are studied, developmental information of fossil arthropods may exhibit developmental patterns not present in living ones. Crustacea possess, basically, a more gradual development than, for example, pterygote insects and would, therefore, be appropriate candidates for the study of fossil ontogenies. Remarkably, famous fossil deposits like the Devonian Rhynie Chert or the Early Palaeozoic ‘Orsten’-type deposits do not comprise the generally macroscopic malacostracan Crustacea (although most probably adult malacostracan fossils have already been found in the Cambrian). By contrast, the Late Jurassic Solnhofen Lithographic Limestones of southern Germany provide thousands of specimens (although only few morphotypes) that can be identified as malacostracan larvae, together with juvenile specimens differing in certain morphological aspects from their conspecific adults. More recent investigations with up-to-date imaging methodology on additional malacostracan crustacean larvae yielded also reconstructible developmental sequences of species from the Solnhofen deposits. The very similar fossil deposits of the Cretaceous lithographic limestones of Lebanon have also yielded malacostracan larvae and juvenile specimens. We present a summary of the occurrences of crustacean fossils providing developmental information and a demonstration of the potential of the lithographic limestones in this context. The importance of developmental data for understanding crustacean evolution is also highlighted.

New malacostracan Crustacea from the Carboniferous (Stephanian) Lagerstätte of Montceau-les-Mines, France

Investigations of recently cracked concretions from the Carboniferous Montceau-les-Mines, France, Lagerstätte led to the recognition of two new malacostracan Crustacea: a palaeophreatoicid isopod, Sottyella montcellensis n. g., n. sp., and a gorgonophontid stomatopod, Chabardella spinosa n. g., n. sp. The occurrence of the palaeophreatoicid isopod Palaeocrangon is discussed, and a new specimen of the syncarid Palaeocaris secretanae allows us to clarify some of its morphological characters. The recognition of these taxa increases the faunal inventory of malacostracans in the Montceau-les-Mines Lagerstätte.

Muscle precursor cells in the developing limbs of two isopods (Crustacea, Peracarida): an immunohistochemical study using a novel monoclonal antibody against myosin heavy chain.

In the hot debate on arthropod relationships, Crustaceans and the morphology of their appendages play a pivotal role. To gain new insights into how arthropod appendages evolved, developmental biologists recently have begun to examine the expression and function of Drosophila appendage genes in Crustaceans. However, cellular aspects of Crustacean limb development such as myogenesis are poorly understood in Crustaceans so that the interpretative context in which to analyse gene functions is still fragmentary. The goal of the present project was to analyse muscle development in Crustacean appendages, and to that end, monoclonal antibodies against arthropod muscle proteins were generated. One of these antibodies recognises certain isoforms of myosin heavy chain and strongly binds to muscle precursor cells in malacostracan Crustacea. We used this antibody to study myogenesis in two isopods, Porcellio scaber and Idotea balthica (Crustacea, Malacostraca, Peracarida), by immunohistochemistry. In these animals, muscles in the limbs originate from single muscle precursor cells, which subsequently grow to form multinucleated muscle precursors. The pattern of primordial muscles in the thoracic limbs was mapped, and results compared to muscle development in other Crustaceans and in insects.Electronic supplementary materialThe online version of this article (doi:10.1007/s00427-008-0216-1) contains supplementary material, which is available to authorized users.

Diet of demersal fish species in relation to aquaculture development in Scottish sea lochs

The diets of demersal fish, principally haddock ( Melanogrammus aeglefinus), whiting ( Merlangius merlangus) and several flatfish species, sampled from four Scottish sea lochs (Hourn, Kishorn, Duich and Nevis) which support aquaculture sites, were examined in order to determine whether the impact of aquaculture on benthic biodiversity would affect the diets of demersal fish. Loch Kishorn had the highest maximum planned aquaculture production, loch Nevis follows and lochs Hourn and Duich have the lowest planned production. Samples were collected from locations less than and more than 2000 m from fish farm cages. Fish close to the fish farm cages were on average of greater individual weight than those further away from fish farms. Haddock ate predominantly Malacostracan crustacea, Ophiurid echinoderms and Polychaete annelids; whiting ate predominantly Malacostracan crustacea and teleost fish and flatfish ate Malacostracan crustacea, Polychaete annelids and Ophiurid echinoderms. A small number of saithe sampled had eaten mainly fish farm pellets. Dietary variation in each species was analysed in relation to loch, proximity to aquaculture facilities and fish size. Diet of whiting varied with body size. Dietary differences were observed between the lochs and between sites close to and far from farms in two lochs although these differences cannot be specifically attributed to aquaculture development. Controlling for differences between individual lochs, proximity to aquaculture facilities did not consistently affect diet composition.

Neurogenesis in the crustacean ventral nerve cord: homology of neuronal stem cells in Malacostraca and Branchiopoda?

In Insecta and malacostracan Crustacea, neurons in the ventral ganglia are generated by the unequal division of neuronal stem cells, the neuroblasts (Nbs), which are arranged in a stereotyped, grid-like pattern. In malacostracans, however, Nbs originate from ectoteloblasts by an invariant lineage, whereas Nbs in insects differentiate without a defined lineage by cell-to-cell interactions within the neuroectoderm. As the ventral ganglia in entomostracan crustaceans were thought to be generated by a general inward proliferation of ectodermal cells, the question arose as to whether neuroblasts in Euarthropoda represent a homologous type of stem cell. In the current project, neurogenesis in metanauplii of the entomostracan crustaceans Triops cancriformis Fabricius, 1780 (Branchiopoda, Phyllopoda) and Artemia salina Linné, 1758 (Branchiopoda, Anostraca) was examined by in vivo incorporation of the mitosis marker bromodeoxyuridine (BrdU) and compared to stem cell proliferation in embryos of the malacostracan Palaemonetes argentinus Nobili, 1901 (Eucarida, Decapoda). The developmental expression of synaptic proteins (synapsins) was studied immunohistochemically. Results indicate that in the ventral neurogenic zone of Branchiopoda, neuronal stem cells with cellular characteristics of malacostracan neuroblasts are present. However, a pattern similar to the lineage-dependent, grid-like arrangement of the malacostracan neuroblasts was not found. Therefore, the homology of entomostracan and malacostracan neuronal stem cells remains uncertain. It is now well established that during arthropod development, identical and most likely homologous structures can emerge, although the initiating steps or the mode of generation of these structures are different. Recent evidence suggests that adult Entomostraca and Malacostraca share corresponding sets of neurons so that the present report provides an example that those homologous neurons may be generated via divergent developmental pathways. In this perspective, it remains difficult at this point to discuss the question of common patterns of stem cell proliferation with regard to the phylogeny and evolution of Atelocerata and Crustacea.

Hormonal Control of Sexual Differentiation and Reproduction in Crustacea

Synopsis. Sexual differentiation in malacostracan Crustacea is controlled by the androgenic gland hormone (AGH). In males, the primordial androgenic glands (AG) develop and AGH induces male morphogenesis. In females, the primordial AG does not develop and the ovaries differentiate spontaneously. Implantation ofthe AG into females yields various results, showing that the sensitivity to AGH differs with the species and the receptive organs. Purified AGH ofthe isopod Armadillidium vulgare consists of at least two molecular forms, which exist as monomeric pro? teins with molecular weights of 17,000 ? 800 and 18,300 ? 1,000 Da and with isoelectric points of about 4.5 and 4.3, respectively. The antiserum raised against purified AGH makes it possible to measure AGH activity by immunoassay. Neurohormones control male and female reproduction. In males, they are involved in the maintenance of the male germinative zone and the control of AG activity. In females, the secondary vitellogenesis is controlled by the vitellogenesis-inhibiting hormone (VIH) and the vitellogenesis-stimulating hormone (VSH). VIH isolated from the lobster Hom? arus americanus is a peptide with a molecular weight of 9,135 Da and shows homology to the crustacean hyperglycemic hormone and moltinhibiting hormone. Involvement ofthe molting hormone and the juve? nile hormone-like compound in the secondary vitellogenesis have also been suggested. In the amphipod Orchestia gammarella, the vitellogenesis-stimulating ovarian hormone (VSOH) seems to control vitellogenin synthesis.

Endocrine and genetic control of sex differentiation in the Malacostracan Crustacea

Summary Sex differentiation in Malacostraca is controlled by hormone secreted from the androgenic glands. Experimentally induced sex inversions in isopods and amphipods proved that the genetic female and male possess primordia of the androgenic glands, gonads, and gonoducts, along with sexual characteristics of both sexes. During the sensitive period, the presence or absence of androgenic gland hormone (AGH) affects the differentiation of these primordia. Genetic control of the development of androgenic gland primordium seems to be brought about assuming of the following: 1. Both genetic female and male possess gene(s) (AGH-G) responsible for the AGH-synthesis situated on the homologous loci of the sex chromosomes and/or on the autosomes. 2. The gene(s) are activated spontaneously with the lack of inhibition of the major sex factor carried by the W or X chromosome. The W and X factors are hypostatic to major sex factor carried by the Y chromosome. The Z factor does not seem to influence sex differentiatio...

Vitellogenesis and Its Control in Malacostracan Crustacea

Vitellogenesis in the amphipod Orchestia gammarella, in natantian decapods and probably in other Malacostraca involves two phases, primary and secondary vitellogenesis. Oogenesis from oogonia to the end of primary vitellogenesis is a continuous process. The primary proteic vitellus is endogenous. The secondary vitellogenesis takes place during the reproductive season. Fully grown primary follicles are surrounded by a permanent follicular tissue (secondary folliculogenesis). The resulting secondary follicles grow synchronously until ovulation. A tubular network has been observed in secondary follicle cells of prawns. The prominent feature of secondary vitellogenesis is the uptake of vitellogenin by the oocytes. This vitellogenin is synthesized by the fat body. Secondary vitellogenesis is controlled by neurohormones that have not yet been isolated and whose modalities of action still remain unclear. In Decapoda, the classical gonad-inhibiting hormone or GIH released by the sinus glands inhibits secondary vitellogenesis and the synthesis of vitellogenin. In Isopoda, vitellogenesis-inhibiting hormone is synthesized by neurosecretory cells in the median part of the protocerebrum. In Amphipoda, neurosecretory cells of this region secrete a neurohormone inducing secondary folliculogenesis and triggering secondary vitellogenesis. The neurohormones would control the formation of functional secondary follicles during the reproductive season. Other hormones are involved in control of secondary vitellogenesis. In Peracarida molting hormone is necessary for a normal synthesis of vitellogenin and the uptake of this protein by growing oocytes. In the amphipod Orchestia gammarella secondary folliculogenesis requires a low titer of ecdysteroids which characterizes postecdysis. The correlation between molt cycle and secondary vitellogenesis would be established in this way. After secondary folliculogenesis, the secondary follicle cells become endocrine and secrete the vitellogenin-stimulating ovarian hormone (VSOH).

Malacostracan Crustacea from the Dinantian of Foulden, Berwickshire, Scotland

ABSTRACTThe Tealliocaris and Crangopsis previously recorded from Foulden are shown to be Bairdops elegans and Belotelson traquairi, respectively. This locality thus yields the oldest Known Bairdops. The two species are confined to the lower Carboniferous sedimentary basin S of the Southern Uplands massif. Elsewhere, these genera are thought to characterise the nearshore marine fauna. The reciprocal relationship noted between malacostracans and actinopterygians may therefore be a function of fluctuating salinity.

The Refractive Index Gradient in the Crystalline Cones of the Eyes of A Euphausiid Crustacean

ABSTRACT The eyes of the euphausiids, a group of malacostracan Crustacea, show a remarkable similarity to the superposition (Exner, 1891) eyes of moths. In both groups the eye has an outer layer of crystalline cones, a wide clear zone, and a layer of rhabdomes beneath it, whose radius of curvature is about half that of the eye itself (Fig. 2 a). We demonstrated recently that image formation in these eyes is indeed performed by a refracting superposition mechanism (Land, Burton & Meyer-Rochow, 1979), as supposed by Chun (1896). That is to say, light is bent by the crystalline cones in such a way that a ray reaching the outer surface of a cone, and making an angle α with the cone axis, is bent in the cone through an angle 2α (Fig. 1). This is the condition necessary if all parallel rays are to be brought to a focus in the rhabdome layer, where an erect image is produced (see Horridge, 1975). This mechanism, shared by moths, fireflies and some other beetles, is not the same as that of the decapod shrimps and prawns, where essentially the same trick is performed not by refracting cones, but by mirrors (Vogt, 1977; Land, 1978). Kampa (1965) proposed that the euphausiid eye was basically of the apposition type, with the cones funnelling light down light guides into the rhabdomes. However, the cones send light, as noted above, and the light-guides are not present (Meyer-Rochow & Walsh, 1979).

DIURNAL VERTICAL MIGRATIONS OF DEEP-WATER PLANKTON

1. A study was made with the aid of closing nets of the diurnal vertical migrations of bathypelagic organisms at a station in continental slope water of the western North Atlantic.2. While the hauls were being made a continuous record of the light intensity at the surface was kept.3. The penetration of light into the upper 84 m. of water was directly measured photometrically; the average extinction coefficient for green light was κ = 0.092.4. All of the malacostracan Crustacea (to which the detailed results presented in this paper are limited) which occurred in sufficient numbers for analysis exhibited diurnal migrations 200 to possibly 600 m. in vertical extent.5. The speed of vertical movement in these migrations varied from 24 to 125 m. per hour among the various crustaceans.6. A considerable part of the migrations took place while the light intensity even at the surface was no greater than starlight.7. Several Crustacea living at 800m. during the day showed extensive diurnal vertical migrations.8. It ...