scholarly journals FINE STRUCTURE AND COMPOSITION OF A SILICEOUS SPONGE SPICULE

1971 ◽  
Vol 140 (1) ◽  
pp. 125-136 ◽  
Author(s):  
DANIEL W. SCHWAB ◽  
RICHARD E. SHORE
Keyword(s):  
Fine Structure ◽  
Siliceous Sponge ◽  
Sponge Spicule

Occurrence of the siliceous sponge spicule Konyrium (Hexactinellida) in the upper Cambrian of the Mackenzie Mountains, northwestern Canada

2002 ◽  
Vol 76 (3) ◽  
pp. 565-569 ◽  
Author(s):  
Brian R. Pratt
Keyword(s):  
Fossil Record ◽  
Southern China ◽  
South Australia ◽  
Early Cambrian ◽  
Siliceous Sponge ◽  
Sponge Spicule ◽  
Animal Phyla ◽  
Sponge Diversity ◽  
Siliceous Sponges ◽  
Late Neoproterozoic

The fossil record of siliceous sponges—Hexactinellida and demosponge “Lithistida”—hinges upon both body fossils plus isolated spicules mostly recovered from limestones by acid digestion. The earliest record of siliceous sponge spicules extends back to the late Neoproterozoic of Hubei, southern China (Steiner et al., 1993) and Mongolia (Brasier et al., 1997), and body fossils attributed to the hexactinellids have been described from the Ediacaran of South Australia (Gehling and Rigby, 1996); thus they are the oldest-known definite representatives of extant animal phyla. The Early Cambrian saw a remarkable diversification in spicule morphology, with the appearance of an essentially “modern” array of forms (Zhang and Pratt, 1994). While a diversity decline may have occurred with the late Early Cambrian extinction(s), the subsequent Paleozoic and Mesozoic fossil record of spicules shows a relatively consistent range of morphologies (e.g., Mostler, 1986; Bengtson et al., 1990; Webby and Trotter, 1993; Kozur et al., 1996; Zhang and Pratt, 2000). However, because spicule form is not restricted to individual taxa and many sponge species secrete a variety of spicule shapes, it is difficult to gauge true siliceous sponge diversity and to explore their biostratigraphic utility using only isolated spicules.

A new Gorstian radiolarian fauna from the upper Silurian of the Cape Phillips Formation, Cornwallis and Bathurst islands, Canadian Arctic

2015 ◽  
Vol 52 (10) ◽  
pp. 863-879 ◽  
Author(s):  
Martin Tetard ◽  
Paula J. Noble ◽  
Taniel Danelian ◽  
Claude Monnet ◽  
Alfred C. Lenz
Keyword(s):  
Canadian Arctic ◽  
Alpha Diversity ◽  
Siliceous Sponge ◽  
Sponge Spicule ◽  
Cape Phillips Formation ◽  
Cortical Shell ◽  
Stratigraphic Ranges ◽  
Shelf Margin ◽  
Cornwallis Island

This study provides a taxonomic treatment and comparison of lower Gorstian (Silurian) radiolarians recovered from two sections of the Cape Phillips Formation in the Canadian Arctic that accumulated in two different paleoenvironmental settings. Twilight Creek is more basinal, located ∼100 km from the paleo-shelf margin, whereas Snowblind Creek is located within 1 km of the paleo-shelf break, on Cornwallis Island. The fauna, like other material from the Cape Phillips Formation, is extremely well preserved and was recovered from four samples at two localities, all from the Lobograptus progenitor graptolite Zone, an interval that has few published studies regarding radiolarians. A total of 28 species are recognized, of which two are new and described herein (Fusalfanus bilateralis n. sp. and Pseudospongoprunum parvispina n. sp.), belonging to the Haplotaeniatidae, Inaniguttidae, “Sponguridae”, Ceratoikiscidae, Entactiniidae, Palaeoscenidiidae, and Secuicollactidae. Based on these new data, the stratigraphic ranges of some taxa are extended. The species concepts of several closely related inaniguttid species are re-evaluated. As a result, Inanihella tarangulica Nazarov and Ormiston, 1984 is transferred to the genus Fusalfanus Furutani, 1990 based on cortical shell structure, and Inanihella duroacus, Inanihella legiuncula, and Inanihella perarmata are synonymized under Fusalfanus tarangulica sensu lato. Aciferopylorum admirandum is transferred to Fusalfanus and considered a junior synonym of Fusalfanus osobudaniensis. The comparative analysis of taxonomic richness and composition reveals that the more distal sample from Bathurst Island exhibits a slight, but statistically significant, higher alpha diversity at the species rank than the more proximal basin/platform samples from Snowblind Creek. Biodiversity indices at the genus rank produced mixed results, indicating that differences between sites are at best slight. There is also a strong taxonomic separation between the fine and coarse size radiolarian fractions recovered during the sieving of each sample. The siliceous sponge spicule assemblages from these faunas show an inverse diversity relationship to the radiolarians in that Snowblind Creek contains greater alpha diversity than Twilight Creek. This study provides the first documentation of facies-controls in Silurian radiolarian diversity and is useful in evaluating the role of taxa used in biostratigraphy.

Siliceous sponge spicule dissolution: In field experimental evidences from temperate and tropical waters

2017 ◽  
Vol 184 ◽  
pp. 46-53 ◽  
Author(s):  
Marco Bertolino ◽  
Riccardo Cattaneo-Vietti ◽  
Maurizio Pansini ◽  
Chiara Santini ◽  
Giorgio Bavestrello
Keyword(s):  
Siliceous Sponge ◽  
Sponge Spicule ◽  
Tropical Waters

scholarly journals Mississippian (Osagean) Shallow-Water, Mid-Latitude Siliceous Sponge Spicule and Heterozoan Carbonate Facies

2006 ◽  
pp. 1-23
Author(s):  
Evan K. Franseen
Keyword(s):  
North America ◽  
Shallow Water ◽  
Siliceous Sponge ◽  
Inner Shelf ◽  
Sponge Spicule ◽  
Dissolved Silica ◽  
Subaerial Exposure ◽  
Middle Mississippian ◽  
Facies Associations ◽  
Heterozoan Carbonates

Mixtures of biosiliceous and heterozoan-dominated carbonate deposits are commonly interpreted as recording cold-water polar or deep basinal conditions. However, a growing body of literature is documenting examples from the rock record that show these deposits accumulated in shallow-water middle- to low-latitude environments. The continued recognition of ancient neritic heterozoan carbonate and biosiliceous accumulations is broadening our understanding of the various paleoenvironmental controls on their development. Early-Middle Mississippian time was characterized by the development of biosiliceous and carbonate accumulations in North America. This study focuses on Osagean cherty dolomitic strata in cores from the Schaben field in Kansas, which is located in Ness County on the southwest flank of the Central Kansas uplift (CKU). During the Osagean, Kansas was located at approximately 20° S latitude, within the tropical to subtropical latitudinal belt. Study area strata are characterized by shallow-water inner-shelf carbonates that were deposited on a gently southward-sloping shelf (ramp). Two depositional sequences (DS1 and DS2) are identified in cores and are separated by a sequence boundary (SB1) that evidences subaerial exposure. The primary facies in the two depositional sequences include 1) Mudstone-Wackestone (MW); 2) Sponge Spicule-Rich Wackestone-Packstone (SWP); 3) Echinoderm-Rich Wackestone-Packstone-Grainstone (EWPG); and 4) Dolomitic Siltstones and Shale facies. Other features identified in cores include 1) Silica Cementation and Replacement; 2) Silica Replaced Evaporites; 3) Brecciation and Fracturing; and 4) Calcite Cementation and Replacement. The abundance of echinoderm facies with other diverse fauna, evidence of extensive reworking by burrowing organisms, and only rare occurrence of evaporites suggest subtidal deposition in a normal to slightly restricted marine inner-shelf setting for DS1. After the SB1 subaerial exposure event, marine conditions returned but the depositional environment over the study area changed compared to that for much of DS1 deposition. The volumetric increase of sponge-spicule wackestone and packstone (SWP) with less diverse fauna, abundance of early evaporites (replaced by silica), and evidence for shallowest water to subaerially exposed conditions throughout DS2 suggest deposition in more restricted environments that likely ranged from restricted inner shelf/protected embayment to evaporative lagoon and possibly supratidal flat. One of the more significant characteristics in DS2 is the dominance of siliceous sponge spicule facies and heterozoan carbonates that were deposited in shallow-water and restricted environments. This study and others from numerous periods in the geologic record are indicating that shallow-marine, mid-latitude biosiliceous and heterozoan carbonates may be more common than previously thought. Especially interesting are the examples from Mississippian (Osagean-Meramecian) strata in North America that show similar facies associations with DS2 strata of this study. The predominance of Early-Middle Mississippian heterozoan carbonate and biosiliceous (spiculitic) deposits, and lack of photozoan deposits, in the mid-latitude shallow-shelf setting in Kansas and surrounding areas was likely due to abundant nutrients and dissolved silica derived from basinal and/or terrestrial sources. Based on available evidence, upwelling of basinal waters rich in nutrients and dissolved silica appears to have been a primary control on shelf margin and shelf facies. Upwelling even may have had a primary imprint on shallow-water, inner-shelf areas, especially during transgression(s). Nutrients and dissolved silica from terrestrial sources may have contributed to the facies associations in shallowest water, inner-shelf areas. However, the available evidence suggests that terrestrial sourced nutrients and dissolved silica were not the dominant control. The results of this study have implications from a petroleum reservoir standpoint. The DS2 sponge spicule, heterozoan carbonate, and silica-replaced evaporite facies in this study form reservoirs in Schaben field and another nearby field composed of similar facies. Because regional upwelling is likely to have had at least some control, facies similar to DS2 strata may form important reservoirs in Lower-Middle Mississippian strata that were deposited in shallow-water inner shelf/ramp settings elsewhere in Kansas and North America. Continuing studies of the controls on biosiliceous and heterozoan carbonate deposition and diagenesis in mid-latitude neritic settings will improve our understanding and predictive capabilities.

scholarly journals Memoirs: Studies in Spicule Formation

1908 ◽  
Vol s2-52 (205) ◽  
pp. 139-157
Author(s):  
W. WOODLAND
Keyword(s):  
Thin Film ◽  
Single Cells ◽  
Siliceous Sponge ◽  
Sponge Spicule ◽  
Calcareous Sponges ◽  
Stage Of Development ◽  
Spicule Formation

1. The earliest stages in development of the Hexactinellid spicule are at present unknown, but there exist reasons for supposing that it originates as a granule enclosed by a spherical syncytium in which cell-outlines are absent, and that the six rays of the hexact grow out from this granule. 2. The earliest stage of development yet discovered is the small hexact, the rays of which do not extend to the periphery of the enveloping syncytium. 3. The rays of the hexact elongate, causing the spherical syncytium at first "to present a more or less octahedral shape, with somewhat concave surfaces and with rounded corners" (Ijima). 4. The rays at length extend beyond the spherical contour of the syncytium (the scleroblast mass), the scleroplasm of which, however, persistently adheres to the rays as a thin film, which occasionally includes nuclei. 5. The peripheral growth of the megasclere type of spicule causes the spherical syncytium enveloping the point of junction of the six rays to dwindle and finally to disappear on account of the distension involved. The whole of the microsclere, with the exception of the terminals, remains permanently enveloped by the spherical syncytium. 6. All tetractinellid and monactinellid spicules originate as granules contained within single cells. In a few instances the spicule arises from several granules within the cell and then consists of separate parts (dragmata, for example). 7. All growth is accretionary. There is no well-authenticated instance of a siliceous sponge-spicule being formed by the fusion of at-first-separate parts--such as occurs in calcareous sponges, for example. 8. With the exception of very large spicules, the nucleus of the distended scleroblast remains single throughout growth. 9. It is a significant fact that spicule formation proceeds on very different lines in each of the three great groups of sponges--the Tetraxonida, Triaxonida, and Calcarea.

A varied Middle Ordovician sponge spicule assemblage from western Newfoundland

2000 ◽  
Vol 74 (3) ◽  
pp. 386-393 ◽  
Author(s):  
Xi-Guang Zhang ◽  
Brian R. Pratt
Keyword(s):  
New Taxa ◽  
Siliceous Sponge ◽  
Sponge Spicule ◽  
Middle Ordovician ◽  
Sponge Body ◽  
Conservative Nature ◽  
Sponge Spicules

Abundant and morphologically fairly diverse siliceous sponge spicules of Darriwilian (Middle Ordovician) age were collected from the Table Cove Formation of Port au Port Peninsula, western Newfoundland. Without co-occurrence of appropriate sponge body fossils, it is difficult to refer these disarticulated sponge spicules to existing or to new taxa. However, representatives of demosponges and hexactinellids are recognized. While marked differences are noted between older and younger lithistid dendroclones, for example, spicule form in these Middle Ordovician specimens is similar overall to previously known assemblages of various ages, demonstrating the morphologically conservative nature of the spicular skeleton.

Fine Structure of Platelet Interaction with a New Microcrystalline Collagen Preparation

1974 ◽  
Vol 32 ◽  
pp. 58-59
Author(s):  
W. H. Zucker ◽  
R. G. Mason
Keyword(s):  
Fine Structure ◽  
Platelet Aggregation ◽  
Hydrochloric Acid ◽  
Whole Blood ◽  
Platelet Adhesion ◽  
Hemostatic Agent ◽  
Native Collagen ◽  
Fibrillar Morphology ◽  
Clinical Interest ◽  
New Form

Platelet adhesion initiates platelet aggregation and is an important component of the hemostatic process. Since the development of a new form of collagen as a topical hemostatic agent is of both basic and clinical interest, an ultrastructural and hematologic study of the interaction of platelets with the microcrystalline collagen preparation was undertaken.In this study, whole blood anticoagulated with EDTA was used in order to inhibit aggregation and permit study of platelet adhesion to collagen as an isolated event. The microcrystalline collagen was prepared from bovine dermal corium; milling was with sharp blades. The preparation consists of partial hydrochloric acid amine collagen salts and retains much of the fibrillar morphology of native collagen.

Pituitary Follicular Cells: Their Origin, Possible Function and Fate

1974 ◽  
Vol 32 ◽  
pp. 34-35
Author(s):  
E. Horvath ◽  
K. Kovacs ◽  
G. Penz ◽  
C. Ezrin
Keyword(s):  
Fine Structure ◽  
Secretory Granules ◽  
Follicular Cells ◽  
Human Pituitary ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Junctional Complexes

Follicular structures, in the rat pituitary, composed of cells joined by junctional complexes and possessing few organelles and few, if any, secretory granules, were first described by Farquhar in 1957. Cells of the same description have since been observed in several species including man. The importance of these cells, however, remains obscure. While studying human pituitary glands, we have observed wide variations in the fine structure of follicular cells which may lead to a better understanding of their morphogenesis and significance.

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