Incurrent Canals Research Articles

Choanocyte dimensions and pumping rates in the demosponge Halichondria panicea

The individual choanocyte pumping rate in choanocyte chambers (CCs) is important for understanding the hydrodynamics in sponges and has hitherto been based on measured volume-specific filtration rate and estimated CC density. However, the CC density may vary in different regions of the sponge and to circumvent this uncertainty and to get precise measurements of the individual choanocyte pumping rate, a new experimental approach was developed. Here the aim was to measure the individual pumping rate of choanocytes based on live dimensions of CC elements and particle tracking to measure the speed of small particles entering into the CCs. This was done by using combined live-cell imaging in sandwich cultures of the marine demosponge Halichondria panicea and video-tracking of particles. Small 2 μm-beads and cyanobacteria (Cyanobium bacillare) in the incurrent canal enter the CCs via a 3.3 ± 0.9 μm diameter prosopyle to be subsequently captured by the choanocytes whereas larger algal cells (Rhodomonas salina) and 10 μm-beads are captured in the incurrent canals. CC diameters were positively correlated to the diameter of choanocytes, indicating a total of 84 choanocytes per CC with mean diameter 22.9 ± 6.2 μm. The pumping rate per choanocyte (Qc) was estimated to be between 54 and 68 μm3 s−1. Regardless of demosponge species and based on data in the literature, a choanocyte is suggested to pump between 50 and 100 μm3 s−1.

Fate of microplastic captured in the marine demosponge Halichondria panicea

Microplastic particles are widespread pollutants in the sea and filter-feeding sponges have recently been suggested as useful monitoring organisms. However, the fate of microplastic particles in sponges is poorly understood, yet crucial for interpreting monitoring data. The present study aims to help develop sponges as more useful monitoring organisms for microplastic in the sea. Here, we describe the fate of inedible (2 and 10 μm) plastic beads compared to that of edible bacteria and algal cells captured in the marine demosponge Halichondria panicea. Small Cyanobium bacillare cells entered the choanocyte chambers and were phagocytized by choanocytes, while larger Rhodomonas salina cells were captured in incurrent canals and phagocytized in the mesohyl. Small 2 μm-beads were captured by choanocytes and subsequently expelled into the excurrent canals after 58 ± 34 min. Larger 10 μm-beads were captured in the incurrent canals and transferred to the mesohyl, where amoeboid cells moved them across the mesohyl before they were expelled into the excurrent canal after 95 ± 36 min. SEM observations further indicated engulfment of plastic beads on the outer sponge surface. This insight provides useful information on how sponges, in general, treat microplastic particles of various sizes. It helps us understand actual measured sizes and concentrations of microplastic particles in sponges in relation to those in the ambient water.

Geology and lithological and structural conditions of brecciated rocks localization of the central part of the Ukrainian Shield (as an example of the Hruzske field of pipe-like bodies)

The main purpose of the article — is using the complex of structural-tectonic, geological-geophysical and lithologic-structural investigations, to describe in general the brecciated formations and pipe-like bodies of their localization as a precondition for solving the diamond-bearing problems of the Raihorodska suite (Paleocene) by the example of the Hruzske field of explosive structures in the central part of the Ukrainian Shield. Structural-tectonic, geophysical and morphostructural analyzes of the Precambrian basement surface have been used for diagnostics and outlining of local isometric pipe structures. Petrographic composition of the Hruzske field rocks was studied in core samples from wells No. 4087 (structure Hruzka-Pivdenna), 4040, 4043 and 4045 (structure Lisova-Skhidna), drilled by GPE-37 SE «Kirovheolohiia». Lithologic-stratigraphic and micropaleontological methods were used to determine the age of brecciated rocks. The morphology of bodies, some specific petrographic peculiarities of brecciated rocks of the Hruzske field are characterized by the complex of lithologic-structural features, as well as conclusions regarding their belonging to the endogenous (magmatogenic) group of diamond-bearing formations are made. Brecciated rocks of the Raihorodska suite are attributed to the clay-fine-clastic breccias, which are clearly confined to the lows in the Precambrian basement of the Shield central part and fill the depressions like the diatremes. Their explosive nature is substantiated; the Cretaceous-Palaeogene age of formation is confirmed; the rocks are compared with «sandy» tuffs of the Argyle lamproite pipe in Western Australia and volcanoclastic kimberlites of the Fort a la Corne area in Canada. It has been shown for the first time that the depressions in the Precambrian basement of the Ukrainian Shield central part are pipe-shaped bodies of the stockwork-maars type with a clearly expressed non-eroded craterous part. At a depth, they pass into the system of un-oriented joints, which played the role of incurrent canals for a mobile alkaline-ultrabasic magma, rich in volatile components. According to the structural-material characteristics, these specific brecciated formations of the Raihorodska suite are attributed to the products of rapid brecciation during the fluidizate-explosive processes of the maar volcanism development. Based on the performed researches it is possible to estimate the prospects of pipe-like bodies in relation to the search for industrial diamonds deposits on the Shield, to distinguish local structures, perspective on manifestations of explosive processes and related endogenous (kimberlite-lamproite) diamond content.

New observations onCucullusSteiner from the Neoproterozoic Doushantuo Formation of Guizhou, South China

Wang, Y & Wang, X. 2011: New observations on Cucullus Steiner from the Neoproterozoic Doushantuo Formation of Guizhou, South China. Lethaia, Vol. 44, pp. 275–286. The Neoproterozoic genus Cucullus is the most abundant and largest organism in the Miaohe biota in China, but has remained poorly understood both in morphology and classification. New material recently obtained from the upper Doushantuo Formation (Ediacaran) of northeastern Guizhou, South China, indicates that Cucullus bears thin organic walls composed of complex spongin fibres forming vertical filaments, which may have given rise to transverse filaments. Filaments, non-mineralized spongin fibres, which may have served to support body, regularly interweave with each other in a body, and form openings on body sides that may have served as incurrent canals. The top pores may have served as excurrent canals. The overall features, including the organic wall, the complex spongin fibre networks, and the possible canal system of Cucullus, suggest a primitive element of the Demospongea. This benthic organism lived in a low-energy, calm environment near or below the storm wave-base with influence of episodic storms. Cucullus’ base nestled into the muddy substrate and its sacciform body floated in seawater. □ Cucullus, Doushantuo Formation, Neoproterozoic, Porifera, South China.

Geochemical model of genesis of the Kingash platinoid-copper-nickel deposit

71 Kingash ore field with the deposit of the same name is located within the Archean Kan block of Eastern Sayan and does not go beyond the boundary of the new nickel and platinum bearing province with numerous ore bearing massifs [1]. In plan the Kingash massif forms a lens (Fig. 1) comprising two “megalayers”: lower peridotite–pyroxenite–serpentinite and overly ing gabbroid. In section it presents lopolith with a geo physically reflected gravitational stage approximated with a multichamber incurrent canal [3]. Ultrabasic rocks of the massif contain Pechenga type sulfide ore of chalcopyrite–pentlandite–pyrrhotite composition. Geochemical Model of Genesis of the Kingash Platinoid–Copper–Nickel Deposit O. M. Glazunov and T. A. Radomskaya Presented by Academician A.A. Marakushev April 1, 2009

Video and Electron Microscopy of Particle Feeding in Sandwich Cultures of the Hexactinellid Sponge, Rhabdocalyptus dawsoni

Cultured fragments of the hexactinellid sponge, Rhabdocalyptus dawsoni, were observed feeding on 1.0 Jm latex beads. Using contrast-enhanced video microscopy of live cultures, the events preceding, during, and after phagocytosis were observed. Particle ingestion occurred almost exclusively in flagellated areas where the water currents generated by the flagella of collar bodies could trap and hold particles against sponge tissue. Transmission electron microscopy of cultures fixed after feeding on latex beads showed that collar bodies themselves do not participate in particle phagocytosis. Rather, it is the primary and, probably, the secondary reticula of the trabecular reticulum in the flagellated chamber wall which effect phagocytosis. The intact sponge's tissue organization appears admirably suited for particle capture, and these sponges are likely to be, at least in part, particle feeders in their natural habitat. Additional key words: Hexactinellida, Porifera, filter feeding, culture The Hexactinellida (Porifera, subphylum Symplasma) is an enigmatic marine sponge group which has received little attention in the past due to their seclusion in deep waters. However, recent advances exploiting the few shallow-water species available for study have begun to reveal various aspects of their tissue organization, cell biology, and feeding (e.g. Reiswig & Mehl 1991; Boury-Esnault & Vacelet 1994; Leys 1995; Leys & Mackie 1997). Feeding studies have been pursued using two species: Oopsacas minuta TOPSENT 1927, a Mediterranean cave species (Perez 1996), and Rhabdocalyptus dawsoni (LAMBE 1892) a Northeast Pacific fjord species (Wyeth et al. 1996). Investigation of sponge feeding has focused on demosponges (Porifera, subphylum Cellularia), which has established them as non-specific particle feeders. Particles are extracted from water pumped through the body wall by choanocytes. Most tissues of the demosponge body wall have been implicated in particle phagocytosis. In addition to choanocytes, whose collar microvilli strain the current driven by the flagella, exopinacocytes of the dermal surface and endopinacocytes of the incurrent canals have been shown to engulf particles (Schmidt 1970; Diaz 1979; Willenz & Van de Vyver 1982; Imsiecke 1993). Furthermore, investigations of pumping rates (e.g., Reiswig 1971), a E-mail: rwyeth@u.washington.edu feeding and clearance efficiencies (e.g., Reiswig 1975a; Frost 1980), and the demosponge pump design (Larsen & Riisg'ard 1994) have also been conducted. The assumption that hexactinellid and demosponge feeding are the same should not be made a priori, since the two groups differ in the details of tissue organization and structure. In hexactinellids, the dermal membrane, trabeculae of the body wall, and flagellated chamber walls are all formed by the syncytial trabecular reticulum (Mackie & Singla 1983; Reiswig & Mehl 1991; Leys 1999). The hexactinellid aquiferous system consists of broad, expansive incurrent and excurrent canals bounded by a network of trabeculae (Schulze 1887; Ijima 1904; Leys 1999), unlike the smaller diameter canals, bounded by endopinacocytes, found in the demosponges used for feeding studies (Schmidt 1970; Diaz 1979; Imsiecke 1993). The large and oblong hexactinellid flagellated chambers, 60 (Jm or more in maximal dimension, are serviced by proportionately far more prosopyles (Schulze 1887; Ijima 1904; Reiswig & Mehl 1991; Leys 1999) than the smaller (30 Im in diameter) spherical chambers in demosponges used in feeding studies (Reiswig 1975b; Diaz 1979; de Vos et al. 1991). In hexactinellids, the trabecular reticulum branches to create a double reticulum in the chamber wall. The primary reticulum forms the wall of the chamber and encloses the bases of collar bodies. Inside the chamber, the secondary reticulum, offset from the primary, fills the gaps between This content downloaded from 207.46.13.176 on Mon, 20 Jun 2016 07:22:20 UTC All use subject to http://about.jstor.org/terms Hexactinellid sponge feeding collars inside the chamber (Reiswig 1979; Reiswig & Mehl 1991; Boury-Esnault & Vacelet 1994; Leys 1999). Hexactinellid collar bodies, although bearing similar collars of microvilli, are more widely spaced than demosponge choanocytes, are enucleate, and form part of a partially connected network within the flagellated chamber walls (Reiswig 1979; Mackie & Singla 1983; Leys 1999). Furthermore, the 20 tim flagella in hexactinellids are roughly 2-3 times the length of their associated collars (Reiswig 1979; Reiswig & Mehl 1991; Boury-Esnault & Vacelet 1994), considerably smaller than the equivalent ratio in demosponges which may have 45 pLm flagella, 4-6 times the collar length (see Larsen & Riisgard 1994). Although individually none of these structural differences leaps out as a reason to suspect substantial differences between hexactinellid and demosponge feeding, when considered together it is quite possible they could lead to considerable differences in the details of feeding

The Choanosome of Hexactinellid Sponges

Three-dimensional images of the choanosome of hexactinellid sponges can help in explaining how these sponges mix cellular and syncytial tissues in a fine cobweb-like network. Plastic replicas of the water canals show that Rhabdocalyptus dawsoni has large, highly branched incurrent canals, and equally large, although less branched, excurrent canals that are studded with 60 (im-long flagellated chambers. Freeze-fractured, fixed specimens show the syncytial tissue, known as the trabecular reticulum, envelops cells in a thin collagenous mesohyl at the flagellated chambers in both R. dawsoni and Aphrocallistes vastus. Groups of archaeocytes are especially abundant in the mesohyl of R. dawsoni during summer months. A branch of the trabecular reticulum, the secondary reticulum, surrounds the collars in the flagellated chambers, effectively forcing water to be drawn through the collar microvilli. Another branch, the inner membrane, occupies up to 10% of flagellated chambers of sponges during all months of the year, but is especially prevalent in specimens which have been kept in sea water aquaria for several weeks. This three-dimensional view of hexactinellid tissues reinforces the conclusion that hexactinellid sponges be separated from other sponges at the subphylum level. Additional key words: Hexactinellida, Porifera, syncytium, sponge Sponge morphology has been studied for well over a century. These animals are considered to be simple, radially symmetric or asymmetric, diploblastic metazoans that carry out all the basic functions of ingestion and egestion, growth and reproduction with a very small complement of cell types. The Hexactinellida, however, differ fundamentally from other sponges in having a syncytial tissue (the trabecular reticulum) rather than cells, as their major tissue component (Reiswig 1979; Mackie & Singla 1983; Leys 1995). The uniqueness of the construction of the Hexactinellida has been recognized since these animals were first examined in the late 1800s. Bidder (1929) first proposed separating the Porifera into two phyla based partly on the difference in tissue organization between cellular and syncytial sponges. Later, Reid (1963) argued that this difference should be recognized at the subphylum level, but the lack of ultrastructural proof of syncytial tissues prevented sponge workers from unanimously accepting the proposal (Bergquist 1978). Because hexactinellids are predominantly deep water sponges, specimens were usually obtained by dredging, and consequently were in poor condition. The discovery of shallow-water populations accessible by a Present address: Department of Zoology, University of Queensland, Brisbane, QLD 4072, Australia. SCUBA in the late 1970s allowed the first ultrastructural examination of tissues and confirmed that the major tissue component in the sponge constitutes a single giant syncytium (Reiswig 1979; Mackie & Singla 1983). Advances in our understanding of the physiology (Perez 1996; Wyeth et al. 1996; Leys & Mackie 1997), development (Boury-Esnault & Vacelet 1994; BouryEsnault et al. 1999), and molecular biology (Koziol et al. 1997; Kruse et al. 1998) of hexactinellids have confirmed the unusual status of this group within the phylum Porifera. However, recent invertebrate texts have yet to acknowledge a proposal for subdivision of sponges into two subphyla (Reiswig & Mackie 1983). Because hexactinellid tissue is unusually difficult to preserve well for either transmission or scanning electron microscopy (TEM, SEM), it is possible that discrepancies in interpretation of preserved tissue by specialists in this field have been the reason why no text carries a clear description of the tissue organization of these sponges. Despite several excellent articles describing fixed tissues from some eight species of hexactinellids (e.g. Mackie & Singla 1983; Reiswig & Mehl 1991; Boury-Esnault & Vacelet 1994), a clear, three-dimensional picture of their tissues is still lacking. In other sponge groups the flagellated chambers and This content downloaded from 157.55.39.153 on Mon, 19 Sep 2016 04:45:05 UTC All use subject to http://about.jstor.org/terms

Body structure of marine sponges. VI. Choanocyte chamber structure in the haplosclerida (porifera, demospongiae) and its relevance to the phylogenesis of the group

The choanocyte chambers of eight different haplosclerid sponge species have been investigated with regard to their histological structure, their relation to the mesohyl, and their arrangement between the canal systems. Two fundamentally different organizational types occur in the investigated sponge species. In Haliclona rosea, H. oculata, H. elegans, H. simulans, H. rava, H. fistulosa, and Acervochalina limbata the choanocytes are separated from the mesohylar tissue, being more or less covered over the outer surface by pinacocytes belonging to the incurrent canal walls. In Haliclona indistincta, on the other hand, the choanocytes are, as in most other Demospongiae, in contact with the mesohyl at their outer surfaces. This indicates that the present order Haplosclerida is polyphyletic and contains sponges of a presumably poecilosclerid origin.

Formation and construction of asexual buds of the freshwater spongeRadiospongilla cerebellata (Porifera, Spongillidae)

The buds ofRadiospongilla cerebellata are formed asexually. Budding can be induced experimentally by injuring the sponge. The first sign of budding is a slight elevation of some surface areas, which proceed to rise rapidly so that they soon protrude conspicuously from the surface of the sponge. As a bud develops, the broad base joining it to the mother sponge narrows to a stalk, which finally breaks. The free buds drift in the water for 15–20 min and then settle, forming new sessile sponges. The buds, 1.5–2.5 mm in diameter, have an internal organization identical with that of the mother sponge. They are enclosed in a layer of pinacoderm perforated by dermal pores. Under the pinacorderm there is a shallow subdermal space, which is in communication with the incurrent canals leading to the choanocyte chambers. The water sucked into these chambers proceeds into the excurrent canal system and emerges from the sponge through the oscular tube. Spicules projecting radially from the bud bear apical tufts of microscleres. The skeletal spicules of the buds, like their choanocyte chambers, are smaller than those in the mother sponge. The chambers expand to their mature size by choanocyte mitosis. Buds and sponges are colored green by intracellular symbiotic algae of the genusChlorella.

The architecture of the canal systems of Petrosia ficiformis and Chondrosia reniformis studied by corrosion casts (Porifera, Demospongiae)

The three-dimensional organization of the canal system in two sponge species, Petrosia ficiformis and Chondrosia reniformis, was studied using corrosion casts. Casts were made of live animals, in situ, and canal replicas were analzyed by scanning electron microscopy (SEM). In P. ficiformis the incurrent system consists of a superficial canal network giving rise to large radial canals, which ramify and anastomosize forming an internal web. Excurrent canals are arranged into modular ramified systems radiating from atrial cavities opening to the exterior. Main excurrent canals run at various depths within the sponge, even through the superficial incurrent network. Both incurrent and excurrent canal replicas show smooth, blind-ending capillaries. Some large incurrent canals merge with excurrent ones, thus bypassing choanocyte chambers. In C. reniformis there is a cortical collagen layer crossed by three-like incurrent canals, the “twigs” of which communicate with groups of inhalant pores. The stems of tree-like canals penetrate into the sponge medulla where they ramify and anastomosize to form a web. Main excurrent canals arise from large cloacal ducts leading to the oscular openings. They give rise to a sequence of branches intersecting the incurrent web. Both incurrent and excurrent canals have sharp, blind-ending capillaries. Morphometric data functions show that diameter scaling in canal branches is exponential in Petrosia and linear in Chondrosia. Structural differences and homologies between the two species are discussed.

Canal systems and choanocyte chambers in freshwater sponges (Porifera, Spongillidae)

The spongillid species Spongilla lacustris and Ephydatia fluviatilis possess choanocyte chambers of the classical eurypylous type. They are surrounded by the mesenchymal tissue and connected to the incurrent canal system by prosopyles and to the excurrent canal system by wide apopyles. Each apopyle is sealed against spaces between the basal choanocyte collar parts by a ring of uniflagellated cone cells. The functional aspects of the choanocyte chamber and canal structure are discussed.

Body structure of marine sponges

Each choanocyte chamber of Petrosia ficiformis is formed by a slightly outpocked choanocyte epithelium and by a ring of three or four uniflagellated cone cells surrounding the apopyle. The apopyle opens into a small aphodus, which leads the water flow to larger excurrent canals. Pinacocytes of the incurrent canal system cover the basal surface of the choanocytes and separate them from the incurrent canals and the mesenchyme. The water flows into the chambers by pores in the pinacocyte cover and then through gaps between adjacent choanocytes. To our knowledge this is the first report of a leuconoid canal system in which choanocyte chambers are covered by a pinacocyte epithelium of the incurrent canal system that isolates the chambers from the mesenchyme. A future comprehensive revision of the types of canal systems in sponges seems to be necessary.

The uptake of particulate food inReniera sp. (Porifera)

The choanocyte chambers of the marine spongeReniera sp. protrude with their curved outer surface free into the incurrent canals. The water is sucked into the chambers by cavities between the choanocytes. Particles up to 1 µm in diameter may enter the chambers with the water current. These particles are trapped on the outer surface of the choanocyte collars and are ingested by the choanocytes and processes of the pinacocyte epithelium of the incurrent canal system, which project into the chambers. Bigger particles are retained in the incurrent canals mainly on the outer surface of the choanocyte chambers. They are ingested by pinacocytes of the canal wall and transported to cells of the mesenchyme. The present investigation shows the great importance of the pinacocyte epithelium of the incurrent canal system for suspension feeding inReniera sp.

Body structure of marine sponges

The flagellated chambers of the marine sponge Reniera sp. (Haplosclerida) are found at the junctions of the incurrent and excurrent canal systems, in the lumens of the incurrent canals. Each is inserted into the pinacocyte lining of the incurrent and excurrent canal systems by means of a cell ring in the apopyle region. The cohesion of the choanocytes is brought about by processes of the cells that form a lattice bridging the intercellular spaces. The water in the incurrent canals is sucked into the flagellated chambers through these cavities between the choanocytes, driven through the apopyle into the excurrent parts of the canal system by the beating of the choanocyte flagella, and eventually expelled from the sponge. The flagellated chambers are thus pumps to keep the water flowing and simultancously devices to trap the food particles carried in by the current. The described arrangement of the flagellated chambers in the canal system of Reniera sp. differs from all known Leucon-types and should be regarded as a new basic type of leuconoid organisation.

QUANTITATIVE ASPECTS OF FILTER FEEDING IN INVERTEBRATES

QUANTITATIVE ASPECTS OF FILTER FEEDING IN INVERTEBRATES

Descriptions of Fossil Sponges from the Inferior Oolite, with a Notice of some from the Great Oolite

Since up to this time the lists of palæontologists afford no instance of a fossil sponge from the Inferior Oolite of this country, we are the more indebted to my friend Mr. Whidborne for the rich representative collection of these forms amassed by his researches. A preliminary account of this collection is published in the Report of the British Association for 1882, p. 534. I now proceed to offer a more detailed description of its contents. HEXACTINELLIDÆ. DICTYONINA . Euretid æ Emploca , gen. nov. A cylindrical or ovate sponge, with thick walls surrounding the main excurrent canal, which, as a cylindrical tube, extends axially almost to the base of the sponge, and opens unconstrictedly at the summit in a circular oscule. The sponge walls are traversed by two sets of smaller canals, one incurrent, which, commencing in small round ostia evenly dispersed on the external surface, continue inwards obliquely downwards towards the axis; the other excurrent, which, crossing the incurrent canals, run more or less parallel to the curved upper margin of the sponge and finally open into the main excurrent canal. Skeleton Euretid, i.e. a simple Dicytonine network with imperforate nodes ; dermal skeleton not preserved. The genus agrees in general form and in the characters of the canal system with the Hexactinellid Porocypdlia, the Lithistid Siphonia , and an undescribed Renierid sponge. It differs from Porocypellia in the imperforate character of its nodes and in the absence of a staurodormal covering. Emploca ovata , Sp. nov. (Plate XX. figs. 1-6.) The species