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Topic: Demosponges

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	Demospongia
		However, the vast majority of living demosponges do not possess skeletons that would easily fossilize, thus their fossil diversity, which peaks in the Cretaceous, is probably an enormous underestimate of their true diversity.
		Demosponge skeletons are composed of spongin fibers and/or siliceous spicules, though one genus (Oscarella) has neither.
		Demosponge spicules, if present, are siliceous, have one to four rays not at right angles, and have axial canals that are triangular in cross section.
	www.ucmp.berkeley.edu /porifera/demospongia.html (362 words)

	Kid's World - Taxonomy
		Demosponges are the only group that has freshwater members.
		By studying the fossil record, it appears that demosponges were not so common long ago as they are today.
		Since the demosponge spicules are made of a less strong material, when the the bodies decomposed, their spicules could have easily dissolved.
	library.thinkquest.org /26502/level1/taxonomy.htm (0 words)

	Kids.Net.Au - Encyclopedia > Sponge
		Sponges are divided into Demosponges[?], Hexactinellid sponges, and Calcaerous sponges[?] based on the type of spicules in their skeleton.
		Demosponges[?] are less common than other sponges, but that is probably because many demosponges[?] have skelatons made only of relatively soft spongin that does not fossilize well.
		The fossil Archaeocyantha may also belong here, though their skeletons are solid rather than separated into spicules.
	www.kids.net.au /encyclopedia-wiki/sp/Sponge (527 words)

	Sponges: A Bunch of Holes Held Together by Some Cells by Ronald L. Shimek, Ph.D. - Reefkeeping.com
		Demosponges, particularly, grow well from fragments and in some areas clonal sponge populations contain many separate individuals resulting from widespread asexual reproduction due to fragmentation (Hartman and Reiswig, 1973; Reiswig, 1983).
		A few demosponges lack spicules altogether and have only a proteinaceous skeleton; these are the classic "bath sponges." Some others, called "sclerosponges," secrete a massive calcareous skeleton, in which the silicate spicules are imbedded.
		Demosponges tend to be moderately-sized animals, but some are found growing as only thin layers over rocks.
	www.reefkeeping.com /issues/2005-06/rs/index.php (4253 words)

	Krautter: Abstract 1997 (Habil, englisch)
		Demosponges are able to host bacteria to a great amount in their mesohyl.
		Therefore the bathymetric distribution of filter feeding demosponges is strongly influenced by the bathymetric distribution of bacteria and these sponges also decrease towards greater depth.
		Due to this ability, morphovariable demosponges reach a certain independancy of exteral food supply and are able to settle in greater depths, in which they normally are not to be found.
	www.porifera.org /a/bik97e.html (833 words)

	Identification and Husbandry of Aquarium Sponges by Ronald L. Shimek, Ph.D. - Reefkeeping.com
		Obviously, the plasticity of shape seen in most demosponges leads to the obvious question, "If these animals cannot be identified to species simply by looking at them, how are they identified?" The answer is relatively straightforward, actually, as is the identification process.
		The odds of satisfying all of these requirements are slim to none for most hobbyists and, because of that, many of the common demosponges in their tanks cannot be identified with any degree of certainty.
		Compared to demosponges, the calcareous sponges are significantly less diverse, and the ones typically found in aquaria are relatively easy to name.
	www.reefkeeping.com /issues/2005-07/rs/index.php (5372 words)

	NationMaster - Encyclopedia: Sponge
		LOSER sponges are sponges with a skeleton made of four- and/or six-pointed silaceous spicules, often referred to as glass sponges.
		Demosponges are the largest class of Phylum Porifera.
		Although 90% of modern sponges are demosponges, fossilized remains of this type are less common than those of other types because their skeletons are composed of relatively soft spongin that does not fossilize well.
	www.nationmaster.com /encyclopedia/Sponge (3810 words)

	Sponge Information (Site not responding. Last check: )
		Demosponges are the only group that has freshwater members.
		By studying the fossil record, it appears that demosponges were not so common long ago as they are today.
		Since the demosponge spicules are made of a less strong material, when the the bodies decomposed, their spicules could have easily dissolved.
	www.hometown.aol.com /ksmith9526/SpongeInformation.htm (1216 words)

	PALAEONTOLOGIA POLONICA, vol. 57
		The fauna of siliceous sponges (hexactinellids and demosponges) from the Upper Jurassic of the Swabian Alb is described and revised.
		Ecological analysis of the sponge fauna and sedimentological analysis of sponge-bearing sequences point to a relatively deep-water setting of the Upper Jurassic siliceous sponge biofacies: the most shallow mixed sponge-coral Upper Kimmeridgian assemblages dominated by lithistid demosponges could be from 60—100 meters, while Oxfordian hexactinellid dominated assemblages may be from as deep as 200—600 m.
		The apperance of rich siliceous sponge assemblages in the Upper Jurassic is mostly ecological phenomenon since the numerous genera contributing to this assemblage are rooted in the Lower Jurassic at least.
	www.paleo.pan.pl /pp57.htm (389 words)

	Porifera Laboratory Exercises (Site not responding. Last check: )
		Most of the world's sponges are demosponges and all large sponges belong to this taxon.
		Demosponges are always leuconoid, the grade of construction which permits large size by allowing expansion of the choanoderm surface area.
		North American freshwater sponges are demosponges in the taxon Spongillidae.
	local.lander.edu /rsfox/310poriferaLab.html (2938 words)

	Sponges
		By far the most abundant today are the demosponges, which possess a siliceous skeleton of uniaxial, triradiate or tetrahedral spicules.
		Their bodies tend to be extremely complex morphologically, and highly variable; under different conditions, the same species may grow as either an encrusting mat or a branching bush.
		Although some demosponges are known from the Lower Cambrian, in most cases the skeletons were too fragile to fossilise, and they are a very minor component of Palaeozoic faunas.
	www.asoldasthehills.org /Sponges.html (1098 words)

	Reefs.org: Where Reefkeeping Begins on the Internet - Aquarium.Net Nov 96 Sponges
		Demosponges are the animals everyone thinks of when you hear the word "sponge." They typically have siliceous spicules, and often supplement or replace the silica-based skeleton with a collagenous network referred to as `spongin' (this is the material of which your authentic bath sponge is composed).
		The Demosponges are found in marine, brackish and freshwater, and at all depths.
		Growth rates are highly variable among the sponges, but in general, tropical and polar Demosponges tend to live on average from 20 to 100 years.
	www.reefs.org /library/aquarium_net/1196/1196_7.html (3215 words)

	The Wet World of Sponges - Taxonomy - Demosponges
		Having originated relatively with the Calcarea and Sclerospongiae, in the Cambrian period, the demonsponges are not as progressively ancient as the Hexactinellids.
		Due to their predominately silica structure, it is theorized that many demosponges did not fossilize.
		Also, for some miscellaneous facts, demosponges are the only class of porifera implemented for commercial sponges.
	library.thinkquest.org /26502/level2/Taxonomy/demos.htm (0 words)

	IngentaConnect Cyathophycus and the origin of demosponges
		Molecular phylogenies appear to be reaching a consensus that the hexactinellids and demosponges are closely related, despite previous attempts to separate the Hexactinellida from other sponges on cytological grounds, but the details of the transition are unknown.
		Similarities of spicule morphology and structure are used to infer that the transition probably occurred after the onset of silicification, and should therefore be seen in fossils.
		Although the direction of evolution cannot be certainly fixed, it is conceptually much easier to derive the demosponges from the hexactinellids, rather than vice versa.
	www.ingentaconnect.com /content/tandf/slet/2003/00000036/00000004/art00006 (0 words)

	Characteristics of the Phylum Porifera
		In most demosponges (= most sponge species) the larva is called a
		The sponge below (left) is the yellow connective tissue remains of a demosponge that
		It is one of about 12 species in that class whose skeleton is composed entirely of
	www.fiu.edu /~goldberg/coralreefs/NewPorifera.htm (1754 words)

	Inter Research » MEPS » v164 » p301-306
		Many demosponges are known to have fusible larvae that form young chimeric sponges, but the ecological and evolutionary significance of this phenomenon has seldom been investigated.
		In a 50 d field-transplantation experiment using chimeric sponges obtained from the fusion of 2 sibling larvae, I also tested the hypothesis that size and survival are increased in chimeric individuals compared to non-chimeric ones and investigated the permanent versus transitory character of this chimerism.
		These results disprove the common argument that the capacity of fusion with conspecifics is evolutionarily retained in many sponges because the gain in size after fusion improves the chances of survival of the resulting chimeric individual.
	www.int-res.com /abstracts/meps/v164/p301-306 (375 words)

	SICB - 2004 meeting - Abstract Details (Site not responding. Last check: )
		Demosponges are hypothesized to belong to the most basal metazoan clade.
		Despite their importance to our understanding of metazoan evolution and aquatic ecology, we have only a rudimentary knowledge of the internal relationships of major demosponge clades.
		Sparse knowledge of demosponge phylogeny can be attributed to a dearth of complex morphological characters useful for cladistic analyses.
	www.sicb.org /meetings/2004/schedule/abstractdetails.php3?id=925 (196 words)

	Biogeography of Ordovician sponges Journal of Paleontology - Find Articles (Site not responding. Last check: )
		Demosponges were briefly analyzed by Rigby and Webby (1988) and Rigby and Chatterton (1989).
		Finks (1967), Rigby (1983, 1991), and others have emphasized that records of several major sponge groups begin in the Ordovician, but their origins from Cambrian sponges are obscure.
		The lithistid astylosponge Sphaerocladina, the hindd Tricranocladina, and the Rhizomorina and Megamorina are examples of such groups that may have had their origins from primitive monaxonic demosponges such as Hazelia or Hamptonaa, as visualized by Finks (1967).
	www.findarticles.com /p/articles/mi_qa3790/is_199901/ai_n8838725 (796 words)

	JGI - Why Sequence Reniera?
		Recent molecular phylogenetic and developmental data indicate that demosponges are part of the most ancient and basal metazoan lineage and have many hallmarks of animal development, including gastrulation and pattern formation.
		Sequencing the genome of the tropical demosponge Reniera will define genetic features that are unique to and shared by all animals--humans to sponges--and are likely to have been present in the genome of the very first animals.
		The molecular basis of biomineralization of the siliceous spicules present in demosponges such as Reniera is a target for marine biotechnology and the communications industry.
	www.jgi.doe.gov /sequencing/why/CSP2005/reniera.html (229 words)

	Lizard Island Research Station - Publications 1997
		Biomineralization of calcified skeletons in three Pacific coralline demosponges - an approach to the evolution of basal skeletons.
		Spatial and temporal validation of settlement-marks in the otoliths of tropical reef fishes.
		Woerheide, G. (1997) The reef cave dwelling ultraconservative coralline demosponge Astrosclera willeyana Lister 1900 from the Indo-Pacific.
	www.lizardisland.net.au /research/publications/1997.htm (874 words)

	Biology 105 (Site not responding. Last check: )
		About 95% of living sponge species are demosponges, with an estimated global fauna of 15,000 species.
		Demosponges exhibit a wide range of growth forms, ranging from thin encrusting films, to massive, tubular, plate-like, barrel-shaped, branching, or tree-like growth forms.
		One of three orders of demosponges that lack spicules (others are the Dendroceratida and Verongida); these orders are collectively known as the keratose sponges.
	www.flmnh.ufl.edu /malacology/IZ2005/LabNotes/lab2.htm (4599 words)

	Feb. 6
		Major structural protein of animal kingdom is collagen; fibrils of collagen found throughout the intercellular matrix of all sponges.
		Demosponges secrete a form a collagen called spongin.
		Marine Demosponges are varied in both form and color: tall or encrusting, shaped like fans, vases, cushions or balls (Fig 17.11) Some bore into coral skeletons or mollusk shells; loggerheads grow several m.
	www.ltcconline.net /kloss/bio212/feb__6.htm (1581 words)

	[No title] (Site not responding. Last check: )
		Wörheide G. and Reitner, J. (1999): Biogeography and taxonomy of the reef cave dwelling coralline demosponge Astrosclera willeyana throughout the Indo-Pacific.
		Wörheide G., Degnan, B.M., Hooper, J.N.A. and Reitner, J. (2000): Biogeography and taxonomy of the Indo-Pacific reef cave dwelling coralline demosponge Astrosclera willeyana - new data from nuclear ITS gene sequences.
		Wörheide, G. and Reitner, J. (1998): Biogeography and taxonomy of the reef cave dwelling coralline demosponge Astrosclera willeyana throughout the Indo-Pacific.
	wwwuser.gwdg.de /~gwoerhe/bibliography.html (3470 words)

	Palaeos Metazoa: Porifera: Porifera (Sponges)
		Both hexactinellids and demosponges make spicules in about the same way, using the same enzymes.
		One of those enzymes is silicase, which is almost identical to a form of carbonic anhydrase.
		Amphimedon (and, to a lesser extent, the hydrozoan, Hydra) are thus far the only organisms to have an intermediate condition.
	www.palaeos.com /Invertebrates/Porifera/Porifera.htm (0 words)

	Metamorphosis of Coeloblastula Performed by Multipotential Larval Flagellated Cells in the Calcareous Sponge ...
		demosponges (Amano, 1986, 1988; Maldonado and Young, 1996).
		Metamorphosis of a demosponge I. Cells and structure of swimming larva.
		Transdifferentiation of larval flagellated cells to choanocytes in the metamorphosis of the demosponge Haliclona permollis.
	www.biolbull.org /cgi/content/full/200/1/20 (3842 words)

	Western Australian Museum - Sponges
		Typically pale in colour and with a tendency to be quite small in size (less than 30cm), this class of sponges lacks spongin; their skeletons are composed entirely of calcium carbonate and as a result they are quite brittle to touch.
		The demosponges comprise 95% of the world's sponges and include the most colourful species.
		Unlike the other four classes whose members are all marine, demosponges can also be found in freshwater.
	www.museum.wa.gov.au /collections/natscience/aquaticzoology/sponges.asp (371 words)

	Marine Chemical Ecology (Site not responding. Last check: )
		The most commonly held theory is that these compounds are distasteful to potential predators, but they may also protect sponges from fouling or overgrowth.
		This research program, funded by the National Science Foundation’s Biological Oceanography program, is designed to assess the defenses of Caribbean demosponges, a group whose taxonomy and chemistry is fairly well described.
		Because reef sponges are abundant, sessile, elaborate putative structural and chemical defenses, and are subject to grazing from generalist and specialist predators, they provide a useful group for testing fundamental hypotheses proposed by terrestrial ecologists about plant defensive mechanisms.
	people.uncw.edu /pawlikj/chemical.html (289 words)

	[No title] (Site not responding. Last check: )
		Demosponges are the dominant class of living sponges, with approximately 600 living genera.
		However, few of these have solidly fused skeletons that are likely to leave a fossil record.
		They are dominantly marine, but the class includes all known freshwater sponges.
	mac01.eps.pitt.edu /geoweb/courses/GEO1200/lab3/classification.htm (148 words)

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