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Topic: Chelicerata


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In the News (Sun 22 Nov 09)

  
  Chelicerata - Wikipedia, the free encyclopedia
The Subphylum Chelicerata constitutes one of the major subdivisions of the Phylum Arthropoda, including the arachnids, horseshoe crabs, and related forms.
In the Chelicerata, the body is divided into an anterior prosoma (or cephalothorax) composed of eight segments plus a presegmental acron and a posterior opisthoma (or abdomen) composed of twelve segments plus a postsegmental telson.
Sometimes they are excluded from the Chelicerata but grouped with them as the Cheliceriformes.
en.wikipedia.org /wiki/Chelicerata   (379 words)

  
 NationMaster.com - Encyclopedia: Chelicerata
The Chelicerata are divided into four classes: The chelicerae of spiders are the mouth parts from which the fangs extend.
The arthropod group identified with the subphylum Chelicerata is the class Arachnida.
There are five main subgroups: the Trilobita, Chelicerata, Myriapoda, Hexapoda, and Crustacea, which may be variously ranked from subphyla to classes, with various other taxa introduced above or below them and corresponding changes in the ranks of their subgroups.
www.nationmaster.com /encyclopedia/Chelicerata   (1688 words)

  
 Early history and phylogeny of chelicerates
Chelicerata Heymons, 1901 belongs to a broad clade of arthropods, the Arachnomorpha Heider, 1913.
Chelicerata is monophyletic, diagnosed as above, and is restricted to Lemoneites, Xiphosura, Chasmataspida, Eurypterida and Arachnida.
Presence of chelicerae is difficult to determine in many Lower Palaeozoic fossils and the presence of median eyes (or their tubercle) and some degree of differentiation in the opisthosoma into a preabdomen and postabdomen are better characters for recognising a fossil chelicerate.
members.tripod.com /~DrJasonDunlop/cp4.html   (367 words)

  
 NationMaster.com - Encyclopedia: Arachnid
The arachnids, Arachnida, are a class of joint-legged invertebrate animals in the subphylum Chelicerata.
The cephalothorax is derived from the fusion of the cephalon or head and the thorax.
Antennae (singular antenna), are the paired appendages connecting to the first (and in crustaceans also to the second) segment of the head of the members of all subphyla of the arthropods except Chelicerata.
www.nationmaster.com /encyclopedia/Arachnid   (2019 words)

  
 Subphylum Chelicerata (Spiders and their kin)
The Chelicerata, which I have called a subphylum here for convenience, but which is just as well called a phylum in some texts, is an extremely ancient group of arthropods, including the extinct Eurypterida.
The inclusion of the class Pycnogonida in the Chelicerata is generally accepted but not scientifically proven, the fossil record for pycnogonids is very scant and they differ in many ways from the other chelicerates.
The Chelicerata contain more about 80,000 species known to science most of which are Arachnids divided almost evenly between the spiders and the mites.
www.earthlife.net /chelicerata/chelicerata.html   (433 words)

  
 Nearctica - Natural History - Chelicerata - General
The Chelicerata are one of the four great living subdivisions of the Arthopods.
The fifth major subdivision of the Chelicerata, the Trilobites, went extinct in the Permian at the end of the Paleozoic.
The Chelicerata, in turn, have three major subdivisions: the Pycnogonida (Sea Spiders), Xiphosura (Horseshoe Crabs), and the largest group the Arachnida (spiders, mites, ticks, scorpions, etc.).
www.nearctica.com /nathist/chelic/chelic.htm   (580 words)

  
 Staff-Eskov
A new archaeid spider (Chelicerata: Aranei) from the Jurassic of Kazakhstan, with notes on the so-called "Gondwanan" ranges of recent taxa.
Spiders (Chelicerata: Araneida) as a component of faunas of Cretaceous ambers, with special reference to the spiders from Taimyr ambers.
Archaeid spiders from the Eocene Baltic amber (Chelicerata: Araneida: Archaeidae), with remarks on the so-called "Gondwanan" ranges of recent taxa.
www.palaeoentomolog.ru /Personnel/eskov.html   (931 words)

  
 Arthropoda
Arthropods are bilaterally symmetrical segmented animals with paired and usually jointed appendages, on some or all of the body segments, with chitinous claws.
Discussion: Chelicerata possess chelicerae, though when considering fossils these are often not preserved and accessory characteristics, median eyes and some degree of post-abdominal differentiation, may be more useful diagnostics.
The principal alternative view is the so-called APT hypothesis that the Crustacea form a clade with the Trilobita plus the Chelicerata.
www.peripatus.gen.nz /Taxa/Arthropoda/Index.html   (4669 words)

  
 A CLADISTIC ANALYSIS OF TRILOBITOMORPHA TO CHELICERATA AND CRUSTACEA   (Site not responding. Last check: 2007-09-19)
The Chelicerata, Crustacea, and Trilobitomorpha were analyzed cladistically in order to determine whether the Trilobites are more closely related to the Chelicerates or to the Crustaceans.
The results observed from the phylogram show that the Trilobitomorpha are more closely related to the Crustacea than the Chelicerata, which supports Margulis and Schwartz’s (1998) classification.
The Trilobites, the Crustaceans, and the Chelicerates are all grouped in the phylum Arthropoda, which are believed to have evolved from annelid ancestors.
www.susqu.edu /students/b/bradleyl/Trilobites.htm   (1521 words)

  
 Palaeos Invertebrates: Arthropoda: Arachnomorpha
As such, "Arachnomorpha" or "Arachnata" constitutes a broad taxon that includes the Trilobites, the Chelicerata and a number of primitive Cambrian to Devonian forms that are usually included in the Trilobitomorpha or the Xiphosura.
Included around the base of the "Crown Group" Chelicerata are a number of primitive forms called "Merostomoidea" - which seem to be transitional between Trilobites and Chelicerates proper.
The Cheloniellida, Aglaspidida and Chelicerata represent three distinct arachnomorph taxa, with the Cheloniellida constituting the sister group to the Chelicerata.
www.palaeos.com /Invertebrates/Arthropods/Arachnomorpha.html   (877 words)

  
 Checklist of the Collembola: Are Collembola terrestrial Crustacea?
Arthropoda = Chelicerata + Mandibulata (Crustacea + Atelocerata (Myriapoda + Hexapoda)) according to Snodgrass, 1938; Weygoldt, 1979; Wågele, 1993; Wheeler et al., 1993; Wheeler, 1995, 1998 (cited from Giribet and Ribera, 2000:205).
Arthropoda = Chelicerata + Mandibulata (Myriapoda + Pancrustacea (Crustacea + Hexapoda)) according to Giribet et al., 1996; Giribet and Ribera, 1998; Zrzavy et al., 1998 (cited from Giribet and Ribera, 2000:205).
Arthropoda = (Chelicerata + Myriapoda) + Pancrustacea (Crustacea + Hexapoda) according to Turbeville et al., 1991; Friedrich and Tautz, 1995; Giribet et al., 1996 (cited from Giribet and Ribera, 2000:205); Dove and Stollewerk, 2003.
www.geocities.com /fransjanssens/publicat/crustacn.htm   (9217 words)

  
 Chelicerata   (Site not responding. Last check: 2007-09-19)
The Subphylum Chelicerata constitutes one of the major subdivisions the Phylum Arthropoda including the arachnids horseshoe crabs and forms.
In the Chelicerata the body is divided an anterior prosoma (or cephalothorax) composed of eight segments plus a acron and a posterior opisthoma (or abdomen) composed of twelve segments plus a telson.
As in other arthropods the mouth between the second and third segments but in other groups there is usually a of antennae on the last preoral segment there are none.
www.freeglossary.com /Chelicerata   (314 words)

  
 Invertebrates in General..
Crustacea is one of those and is comprised by the largest specimens of arthropods, the lobsters, which can reach up to 20 kgs.
The characteristic of those animals are that they have antennae and a jaw and are mostly found in sea and sweet water.
Chelicerata are invertebrates which have in common specialized mouth parts and absent antennae and are mostly land dwellers.
www.ecuador-travel.net /information.biodiversity.invertebrates.general.htm   (279 words)

  
 sea spider on Encyclopedia.com   (Site not responding. Last check: 2007-09-19)
Multifactor population limitation: variable spatial and temporal control of spiders on Gulf of Calif...
SEA SPIDER [sea spider] common name for members of the class Pycnogonida, long-legged, rather spiderlike organisms of the phylum Chelicerata, widely distributed in marine waters.
Most are tiny, from 1 to 9 mm (0.04-0.36 in.), and live in littoral regions, crawling about over the surface of sessile animal colonies or seaweeds.
www.encyclopedia.com /html/s1/seaspide.asp   (441 words)

  
 Information on Arthropods  - insects, bugs, spiders, insect collections - science project - butterflies
The subphylum Trilobita contains only the trilobites, which were the dominant arthropods in the early Paleozoic seas (540 to 245 million years ago) but became extinct during the Permian Period (286 to 245 million years ago), at the end of the Paleozoic Era.
Most members of the subphylum Chelicerata belong to the class Arachnida, containing the spiders, scorpions, ticks, and mites.
They are largely terrestrial arthropods, living beneath stones and logs, in leaf mold, and in vegetation, but there are some aquatic mites that live in fresh water and in the sea.
www.science-store.com /life/animal-info/la010.htm   (718 words)

  
 Arthropods at the Cofrin Center for Biodiversity
These animals all have mouthparts called mandibles, which are jaw-like structures that work against one another (although these mandibles have evolved into bizarre and very un-jawlike structures in some groups).
The other subphylum, Chelicerata, have mouthparts called chelicerae, which are either fang-like or pincer-like in form.
As their classification indicates, horseshoe crabs are not related to "true" crabs at all.
www.uwgb.edu /BIODIVERSITY/biota/arthropods/Chelicerata.htm   (697 words)

  
 sea spider. The Columbia Encyclopedia, Sixth Edition. 2001-05   (Site not responding. Last check: 2007-09-19)
Most are tiny, from 1 to 9 mm (0.04–0.36 in.), and live in littoral regions, crawling about over the surface of sessile animal colonies or seaweeds.
Members of this class are relatively common and widely distributed; well over 400 species are known.
Sea spiders are classified in the phylum Chelicerata, class Pycnogonida.
www.bartleby.com /65/se/seaspide.html   (253 words)

  
 Fossil chelicerates and evolution of Chelicerata
Chasmataspids and eurypterids are now extinct, as are several other fossil groups which have been placed as 'sister taxa' to Chelicerata.
Chelicerata can be seen to be set within a wider 'Arachnomorph' grouping, which includes Cambrian forms such as the aglaspids.
Future work may be expected to modify some of these relationships, and confirm or deny hypotheses such as a eurypterid ancestry for terrestrial scorpions.
palaeo.gly.bris.ac.uk /Palaeofiles/Fossilgroups/Chelicerata/fossils.html   (620 words)

  
 Chelicerata - The Columbia Encyclopedia, Sixth Edition - HighBeam Research   (Site not responding. Last check: 2007-09-19)
Chelicerata - The Columbia Encyclopedia, Sixth Edition - HighBeam Research
CHELICERATA [Chelicerata], phylum of the living horseshoe crabs (class Merostomata), the arachnids (class Arachnida), and the sea spiders (class Pycnogonida).
Chelicerates are characterized by the absence of antennae and jaws and the presence of feeding structures (chelicera), which are modified pincerlike appendages used mainly for grasping and fragmenting food.
www.highbeam.com /doc/1E1:Chelicer/Chelicerata.html?refid=ip_hf   (301 words)

  
 A CLADISTIC ANALYSIS OF THE ARTHROPODS
Colin Tudge (2000) classifies the chelicerates in their own phylum, Chelicerata, and includes the crustaceans, myriapods, and insects in 1 phylum named Mandibulata.
Through an analysis of Figure 3, we propose that the chelicerates should be in their own phylum, Chelicerata, while the crustaceans and the uniramids should be united into 1 phylum, we named Mandibulata.
We determined that the chelicerates should be classified as a separate phylum, Chelicerata, while the crustaceans and uniramids should be classified together under Phylum Mandibulata.
comenius.susqu.edu /bi/202/Journal/vol10/number1/ELF.htm   (1511 words)

  
 GLIEDERFüßER   (Site not responding. Last check: 2007-09-19)
Kieferklauenträger (Chelicerata) zum Beispiel mit den Spinnen oder Skorpionen
Das folgende Kladogramm spiegelt die klassische Einteilung der Gliederfüßer wider, wie sie unter anderem von Ax (1999) und Paulus (1997) auf der Basis morphologischer Daten dargestellt wird.
Gliederfüßer (Arthropoda) --N. Kieferklauenträger (Chelicerata) (unter anderem Webspinnen und Skorpione)
www.toonorama.com /encyclopedia/G/Gliederf%FC%DFer   (843 words)

  
 * Chelicerata - (Animals): Definition
Spiders are arthropods and members of the Subphylum Chelicerata.
The creatures included in the sub-phylum Chelicerata with scorpions are: spiders, horseshoe crabs, ticks and mites.
The term chelicerata describes special adaptations used by these organisms when feeding.
en.mimi.hu /animals/chelicerata.html   (61 words)

  
 [No title]
"Courtship and mating behavior in the Pycnogonida (Chelicerata: Class Pycnogonida): a summary." \ul Invertebrate Reproduction and Development\ulnone \f1\b 46 \f0\b0 (1): 63-79.\ The few published observations on pycnogonid courtship and mating behavior are widely scattered in the literature and there are no recent summaries available.
Consequently, the exclusively paternal care which is characteristic of this little-known group of marine invertebates remains understudied by modern behavioral biologists.
Hemocyanin subunit evolution is strikingly different in the Chelicerata, Myriapoda and Crustacea.
franz.krapp.org /endnote/Pycnogonida.rtf   (13768 words)

  
 Order Araneae - Spiders - BugGuide.Net
The Nearctic Spider Database aims to consolidate images, distribution maps, and species descriptions for all species of spider found in North America.
Lots of interesting information about collecting and preserving spider specimens in their newsletter, which is available on their website.
This is an authoritative checklist that aims (pretty much successfully) to list every species of spider ever recorded from California, along with synonyms, range (given in terms of counties) and citations of references in the taxonomic literature.
bugguide.net /node/view/1954/bglink   (606 words)

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