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Topic: Sclerites


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  Sclerite - Wikipedia, the free encyclopedia
For example, the sclerite called the mandible in insects varies dramatically in form between orders, but all the different variations are homologous.
Sclerites are found on a curious collection of early animals including a common spongelike animal called Chancelloria; an armored slug-like form Wiwaxia; an armored worm with a pair of brachiopod-like shells Halkieria; and another armored worm Microdictyon that is generally considered to be a lobopod/onychophore.
It has been suggested that the sclerites of the Cambrian Wiwaxia are homologous with the bristles of annelid worms (Butterfield 1990).
en.wikipedia.org /wiki/Sclerite   (326 words)

  
 Journal of Paleontology: Small problematic phosphatic sclerites from the Ordovician of Iapetus
Eurytholia plates are interpreted as dorsal dermal sclerites from an animal of uncertain affinities.
Whereas sclerites of the type species are symmetrical along a longitudinal profile, those of E. elibata show some degree of asymmetry and require a differentiation between posterior and anterior.
In sclerites of this latter species, the margin nearest to the peak of the ridge is arbitrarily termed posterior.
www.findarticles.com /p/articles/mi_qa3790/is_200101/ai_n8930991   (1235 words)

  
 NOAA Ocean Explorer: Mountains in the Sea 2004
In shallow tropical corals, sclerites are sometimes insufficient as a defense.
We believe the worm induces the coral to secrete over-sized sclerites at the bases of the polyps, which create the tunnels for the worm to inhabit.
Scale worms are common everywhere in the ocean, from shallow water to the deep sea, and they seem to be the major worm group capable of forming commensal relationships with octocorals.
oceanexplorer.noaa.gov /explorations/04mountains/background/commensals/commensals.html   (741 words)

  
 Journal of Paleontology: HALKIERIIDS IN MIDDLE CAMBRIAN PHOSPHATIC LIMESTONES FROM AUSTRALIA
The remaining Georgina sclerites are distinctive enough to discourage their inclusion in A. superstes, but they are not abundant enough to provide detail sufficient for taxonomic description.
In most cases, the sclerites are asymmetric: the blade may curve within the plane of the blade.
(1990) modified this diagnosis, noting the presence of distinctive sclerite types and lateral sclerite zones that may comprise longitudinal canals (canals that flank the central canal) or may be divided into lateral canals or camerae (numerous canals extending outward from the central canal; these can be thought of as transversely divided longitudinal canals).
www.findarticles.com /p/articles/mi_qa3790/is_200405/ai_n9377598/pg_2   (1258 words)

  
 Larval Morphology
Dorsal prothoracic sclerite and foreleg of Ochrotrichia sp.
In some larvae, these sclerites may be very pale and difficult to discern.
Prosternal sclerites of Ochrotrichia xena (Keiper 1999) and Hydroptila armata (Keiper and Foote 1999).
www.cmnh.org /site/ResearchandCollections_InvertebrateZoology_Research_Hydroptilidae_LarvalMorphology.aspx   (325 words)

  
 Palaeos Invertebrates: Procoelomates: Machaeridia
All scleritomes suffer the same preservational problems in that they very easily disarticulate after the organism dies making isolated sclerites and sclerite fragments the most common form of preservation and a limiting factor when reconstructing morphology and anatomy of the organism.
Epimorphic development of the machaeridian scleritome, with all sclerite segments present initially, is supported by the uniform appearance of ornamentation and growth lines, and the presence of occasional growth increments traceable between sclerites in articulated specimens.
This is in contrast to the adding of sclerites through development in other scleritome-bearing taxa, as seems to be the case in coeloscleritophorans, but Halkieria does also exhibit shells growing by accretion.
www.palaeos.com /Invertebrates/Procoelomates/Machaeridia.html   (310 words)

  
 The Talk.Origins Archive Post of the Month: Oct. 1996
Artificial trilobite sclerites may be used as surrogates in flow tank and field experiments to reveal the settling and transport characteristics which affected the deposition of fossil trilobite remains.
The threshold velocity of transport was tested in a hard-floored flow tank for each sclerite model in both concave-up and concave-down attitudes, in three orientations to the current.
For both sclerite types, the concave-down attitude was most stable when either the anterior or side margins faced the current.
www.talkorigins.org /origins/postmonth/oct96.html   (1221 words)

  
 Non-Scleractinian Cnidaria:
Although sclerites can occasionally form solid substrate, the primary contribution of this group to reef structure is the production of calcitic sediment by sclerite production.
The skeleton is bright red in color, and is solid, rather than being composed of sclerites.
The colony structure is composed of vertical tubes resembling the arrangement of a pipe organ.
www.fiu.edu /~goldberg/coralreefs/octocorals.htm   (410 words)

  
 Taxonomy in Aquarium Corals: Part 3 by Eric Borneman - Reefkeeping.com
The shapes and sizes of the sclerites are often different in the polyps, the base, and the interior.
The sclerites and their features are used in classical taxonomy, and these must be prepared from living tissue and then examined, usually by scanning electron microscopy.
Even if one were to extract the sclerites and look at them under a microscope, it is the distinct patterns of bumps, shapes, and protuberances (tubercles) that must be considered.
www.reefkeeping.com /issues/2002-06/eb/index.php   (1863 words)

  
 AIMS Soft Corals and Sea Fans - Sinularia, Family Alcyoniidae   (Site not responding. Last check: 2007-10-29)
Tightly contracted colonies are generally tough and hard, due to a dense mass of large, spindle shaped sclerites in the colony interior (occasionally absent from the lobes).
In most species, the interior sclerites of Sinularia are over 2 mm long, and in a torn section they are easily seen with the naked eye.
Sinularia brassica, with conspicuous surface sclerites and sparse polyps, is found in turbid deeper areas of the GBR.
www.aims.gov.au /pages/softcorals-seafans/soft-corals09-078081.html   (670 words)

  
 Applications of Image Interference: TEASING FOSSILS OUT OF SHALES WITH CAMERAS AND COMPUTERS
The chancelloriids have three distinct types of tissue preservation: sclerites preserved in pyrite (bright in both Figures 12A and 12B), sclerites preserved as a shiny film (semibright in Figure 12A, dark in Figure 12B), and integument preserved as a nonshiny film (same colour as matrix in Figure 12A, darker than the matrix in Figure 12B).
The sclerites are spectacularly preserved in limonite (presumably arising from the weathering of pyrite) and would seem to need no enhancement.
Nonetheless, the sclerites form an intricate meshwork, and many rays are indistinct because they are somewhat buried and lie under a very thin layer of matrix.
palaeo-electronica.org /2000_1/fossils/applic.htm   (764 words)

  
 Reference.com/Encyclopedia/Halkieria
The sclerites are distinguished into three types; the palmate sclerites placed dorsally between the two shellplates, surrounding these there is a zone of sclerites termed the cultrates and along the entire margin, there is a zone of spineshaped sclerites called siculates.
The shellplates and the sclerites was originally of calcium carbonate.
This is supported by the recognition of its sclerites having a similar ultrastructure to that of polychaete chaetae secreted by numerous microvilli.
www.reference.com /browse/wiki/Halkeria   (537 words)

  
 RELATIONSHIPS
Paralampona), the sclerites are much less conspicuous, and were initially thought to be absent.
Lamponoides at node 36, with the latter two genera clustering at node 35 (supported by their long epigynal sclerite and by the presence of a dorsal abdominal scutum in females, paralleled elsewhere).
Lamponicta cluster at node 38 (sternum fused with the epimeric sclerites, paralleled in
research.amnh.org /entomology/lamponid/RELATION.htm   (3211 words)

  
 The Abdomen   (Site not responding. Last check: 2007-10-29)
Each segment of the abdomen consists of a dorsal sclerite, the tergum, and a ventral sclerite, the sternum, joined to one another laterally by a pleural membrane.
At the very back of the abdomen, the anus (rear opening of the digestive system) is nestled between three protective sclerites:   a dorsal epiproct and a pair of lateral paraprocts.
  These appendages consist of four valvifers (basal sclerites with muscle attachments) and six valvulae (apical sclerites which guide the egg as it emerges from the female's body).
www.cals.ncsu.edu:8050 /course/ent425/tutorial/abdomen.html   (663 words)

  
 SICB - 2007 meeting - Abstract Details   (Site not responding. Last check: 2007-10-29)
We examined the mass and morphometrics of the axial skeleton, sclerites, and fleshy tissue of 81 J.
Our results revealed that the relative amount of axial skeleton increases while that of sclerites decreases with colony length, which suggests that during growth, the colony switches from using sclerites to the stronger gorgonin axial skeleton as the main support system.
Club sclerites, dominating the upper colony, are believed to support the feeding polyps and maintain the integrity of local cortex.
www.sicb.org /meetings/2007/schedule/abstractdetails.php3?id=39   (301 words)

  
 Lectures 4/5
basalar and subalar sclerites - involved in wing movements.
- these sclerites transmit movements of the thoraxproduced by the flight muscles to the wing.
-these sclerites and their attached muscles are also used during flight to change wing shape.
www.biology.ualberta.ca /courses.hp/ent207/lec4-5.htm   (336 words)

  
 Corals - A Quick Reference Guide
Another feature of soft corals is the presence of minute, spiny or sand-like skeletal elements known as sclerites (spicules to some folks, though the latter term is used more often for the skeletal spines in sponges).
Soft coral sclerites are made of calcite, a form of calcium carbonate.
Though most don't leave much behind but sandy sclerites when they die, in life the mass of soft corals often rivals that of the stony corals, so they are important reef habitat.
www.petsforum.com /cis-fishnet/books/fpub05c.htm   (494 words)

  
 MACHAERIDIANS OF THE AL ROSE FORMATION, INYO MOUNTAINS, CALIFORNIA   (Site not responding. Last check: 2007-10-29)
Machaeridian sclerites in the Al Rose are preserved as impressions in the mudstone and as yet only isolated material is known.
Three sclerite morphologies occur, which all with certainty can be placed in one scleritome, these are modified outer sclerites, non-modified outer sclerites and inner ones.
In more detail the morphology of these sclerites differ somewhat from other Ordovician plumulitids, especially the flat inner sclerites give a "primitive" appearance and may represent a more ancestral condition than plumulitids with inner sclerites folded around the longitudinal angle.
gsa.confex.com /gsa/2001CD/finalprogram/abstract_3967.htm   (376 words)

  
 NOAA Ocean Explorer: Sclerites from different coral species
A microscope photograph shows the difference between sclerites of two different coral species.
The ‘warty’ orange sclerites are from Paragorgia sp.
and the pin-shaped clear sclerites are from Lepidisis sp.
www.oceanexplorer.noaa.gov /explorations/03mountains/logs/jul15/media/sclerite.html   (47 words)

  
 Small Shelly Fauna
Most are either tiny shells or else the disarticulated components, called sclerites, of an overall protective armour composed of many such parts, called a scleritome (Bengtson et al.
The recovery of articulated specimens composed of multiple sclerites discussed above, such as Wiwaxia, Halkieria and Microdictyon, suggests that much of the remaining "small shelly fauna" represent elements similarly employed as ectodermal armor in bilaterian Metazoa that have yet to be recovered in an articulated form.
Therefore, the absence of engrailed transcription in the ectoderm of modern Onychophora could well be a consequence of evolutionary loss of exoskeletal elements coincident with the loss of a component of engrailed expression associated with skeletal boundaries.
www.peripatus.gen.nz /Paleontology/SmaSheFau.html   (1403 words)

  
 Armored snail (Hydrothermal vent gastropod with iron sulfide scales)   (Site not responding. Last check: 2007-10-29)
Given that hydrothermal vents—geysers on the deep ocean floor emitting mineral compounds that support a thriving ecosystem—were only discovered in 1977, it is perhaps unsurprising that novel organisms showing unique environmental adaptations are regularly reported from expeditions to these areas.
The so-far unnamed snail lives a sedentary life at the base of the fl smokers—the hottest of the oceanic vents that spew mostly iron and dissolved sulfides, which combine to form iron sulfides.
The interior of the sclerites is penetrated by a pulp of pedal tissue, and where the sclerite surface is overlain by adjacent sclerites, a coat of bacteria is present.
www.freerepublic.com /focus/f-news/1017444/posts   (1022 words)

  
 Research Techniques
Macerate for about 5 minutes until a sufficient quantity of sclerites have been dissociated from the tissue sample.
Allow the sclerites to sink, then pipette a quantity of sclerites in ethanol from the container to the center of a glass microscope slide.
Include scientific name, locality, museum collection catalog number, and where on the specimen the sclerites are from (surface coenenchyme, interior coenenchyme, polyp walls, calyces, anthocodiae, tentacles, crown and points, etc.).
www.calacademy.org /research/izg/OctoResearchTech.htm   (273 words)

  
 Inter Research » MEPS » v240 » p117-126
ABSTRACT: Anti-predatory properties of crude organic extracts and calcitic sclerites from the tissues of 32 species of Caribbean gorgonians were examined at natural volumetric concentrations in laboratory feeding assays using the bluehead wrasse Thalassoma bifasciatum.
All of the species tested (100%) yielded predation-deterrent crude organic extracts, but the sclerites of only 2 species (6.3%), Pterogorgia citrina and the encrusting form of Briareum asbestinum, were deterrent.
Contrary to previous studies, results indicated that sclerites do not generally afford gorgonians protection against generalist fish predators, and there was no evidence that the presence of sclerites in gorgonian tissue decreases the nutritional value sufficiently to deter predation.
www.int-res.com /abstracts/meps/v240/p117-126   (319 words)

  
 Plasticity in the Sclerites of a Gorgonian Coral: Tests of Water Motion, Light Level, and Damage Cues -- West 192 (2): ...
Plasticity in the Sclerites of a Gorgonian Coral: Tests of Water Motion, Light Level, and Damage Cues -- West 192 (2): 279 -- The Biological Bulletin
scarring caused colonies to produce longer sclerites at lower densities.
sclerite length in response to scarring of mid-branch regions may function
www.biolbull.org /cgi/content/abstract/192/2/279   (290 words)

  
 KEY TO THE FAMILIES OF OCTOCORALLIA
Polyp leaf sclerites are numerous and conspicuous (spindles and needles).
Sclerites of composed of subhedral or euhedral crystals
Sclerites of the medulla are mostly smooth and curved, partly fused to form a network
www.calacademy.org /research/izg/OCTOFAM.htm   (898 words)

  
 The Panda's Thumb: Orthozanclus
Halkieriids are Cambrian animals that looked like slugs in scale mail; often when they died their scales, called sclerites, dissociated and scattered, and their sclerites represent a significant component of the small shelly fauna of the early Cambrian.
Wiwaxiids were also sluglike, but sported very prominent, long sclerites, and lacked the anterior and posterior shells; their exact position in the evolutionary tree has bounced about quite a bit, but some argument has made that they belong in the annelid ancestry, and that their sclerites are homologous to the bristly setae of worms.
One simplistic picture of their relationship to modern forms was that the halkieriids expanded their shells and shed their scales to become molluscs, while the wiwaxiids minimized their armor to emphasize flexibility and became more wormlike.
www.pandasthumb.org /archives/2007/03/orthozanclus.html   (529 words)

  
 Dzik publications   (Site not responding. Last check: 2007-10-29)
Mongolitubulus spines, from the Early Cambrian Geres Member of the Shabakhty Formation at Koksu, Malyi Karatau, Kazakstan, enables identification of its sclerite variability within the scleritome.
No other sclerotised structures could be matched with the spines, indicating that these were the only sclerotised part of the body and periodically were shed out.
Microdictyon sclerites likely, and even their homology with arthropod eyes cannot be excluded.
www.paleo.pan.pl /people/Dzik/Dzik2003a.htm   (183 words)

  
 GLOSSARY
Mesopleuron sclerites that comprise the side walls of the mesothorax
Pronotum dorsal surface ar sclerite of the first thoracic segment
Sclerite the individual hard plates that form the exoskeleton
www.roberth.u-net.com /glossary.htm   (2777 words)

  
 Mechanics of cuticular elastic energy storage in leg joints lacking extensor muscles in arachnids -- Sensenig and ...
sclerites were measured as the joint was rotated through angles and
of a transarticular sclerite is more similar to the flight and
Key words: leg joint, extensor muscle, arachnid, transarticular sclerite, arthropod, elastic energy storage, resilience
jeb.biologists.org /cgi/content/abstract/206/4/771   (374 words)

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