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Echiura The Echiura, or spoon worms, are a small group of marine animals. They are considered a group of annelids, though they lack the segmented structure found in other members of that group, and are often treated as a separate phylum. The Echiura fossilize poorly and the earliest known specimen in Pennsylvanian (called the upper Carboniferous outside North America). www.ebroadcast.com.au /lookup/encyclopedia/ec/Echiura.html   (75 words)

BioMed Central | Full text | Annelid phylogeny and the status of Sipuncula and Echiura Echiura possess annelid-like features such as the ultrastructure of cuticle and chaetae, the development of the mesoderm, and structure and position of the blood vessels [15]; additionally, their larval nervous system indicates a possible segmented ancestry even though overt segmentation is lacking in adults [13]. Due to this placement of Echiura as a derived annelid group, interpretations of nerve development in echiurans as vestigial segmentation are fully warranted [13]. Echiura is the sister group to Capitellidae as revealed by three nuclear markers and their exclusion from Annelida is significantly rejected. www.biomedcentral.com /1471-2148/7/57   (5544 words)

Phylogeny of the Annelida and allies These suggest that (1) Sipuncula and Echiura are not sister groups; (2) Nemertea are protostomes; (3) Vestimentifera and Pogonophora are protostomes that have a common ancestor with Echiura and (4) Vestimentifera and Pogonophora are a monophyletic clade. It is still undecided whether the Echiura are in Annelida, but it is probable that the vent worms and pogonophorans should be combined, and considered annelids, perhaps at family level, perhaps higher. If Echiura is indeed moved into Annelida it should also be noted that there is a case that the name Echiuridae as proposed by McHugh may be invalid as a junior synonym to Thalassematidae, although in the new, year 2000, code a new article, 35.5. www.annelida.net /phylum-state.html   (5399 words)

Annelida Echiura (spoon worms), at one time regarded as an annelid group (Sedgwick, 1898), has been excluded from Annelida for many years (Newby, 1940). One possibility is that Clitellata/Oligochaeta and Echiura have lost a number of morphological features that would help identify their sister group among polychaetes. The phylogenetic position of the Clitellata and the Echiura - on the problematic assessment of absent characters. www.tolweb.org /tree?group=Annelida&contgroup=Bilateria   (2606 words)

Directory of open access journals Recent analyses of molecular data suggest that Annelida may include other taxa once considered separate phyla (i.e., Echiura, and Sipuncula) and that Clitellata are derived annelids, thus rendering "Polychaeta" paraphyletic; however, this contradicts classification schemes of annelids developed from recent analyses of morphological characters. Given that deep-level evolutionary relationships of Annelida are poorly understood, we have analyzed comprehensive datasets based on nuclear and mitochondrial genes, and have applied rigorous testing of alternative hypotheses so that we can move towards the robust reconstruction of annelid history needed to interpret animal body plan evolution. Using multiple genes and explicit hypothesis testing, we show that Echiura, Siboglinidae, and Clitellata are derived annelids with polychaete sister taxa, and that Sipuncula should be included within annelids. www.doaj.org /doaj?func=abstract&id=206000&openurl=1   (393 words)

NationMaster - Encyclopedia: Polychaetes Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata Oligochaeta - Earthworms and others Acanthobdellida Branchiobdellida Hirudinea - Leeches Class Myzostomida Class Archiannelida (polyphyletic) Class Echiura *Some authors consider the subclasses under Clitellata to be classes The annelids, collectively called Annelida, are a large phylum of animals, comprising the segmented worms, with about... Photomontage of plankton organisms Plankton are drifting organisms that inhabit the water column of oceans, seas, and bodies of fresh water. Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata Oligochaeta - Earthworms and others Acanthobdellida Branchiobdellida Hirudinea - Leeches Class Myzostomida Class Archiannelida (polyphyletic) Class Echiura *Some authors consider the subclasses under Clitellata to be classes The annelids, collectively called Annelida (from Latin annellus little ring), are a large phylum of animals, comprising... www.nationmaster.com /encyclopedia/Polychaetes   (1030 words)

Echiura Animalia Flora and Fauna Immunohistochemical analysis (cLSM) of the development and organization of the nervous system in Echiura and the phylogenetic implications of these results Echiura, The work of Rene Hessling shows volume rendered three-dimensional reconstructions of the central nervous system of Bonellia viridis. The results suggest that the Echiura do not form a distinct phylum but should be consided as a subtaxon of Annelida. This study conducted by Jeff Judd at San Francisco State University was a general survey of the natural history, feeding and digestive physiology of Urechis caupo, the fat innkeeper worm. www.en.interactiva.org /Echiura/Science/Biology/Flora_and_Fauna/Animalia   (267 words)

IBSS NASU.Sevastopol. V.Murina. Phylum Echiura The Echiura popularly called "spoon-worms" are inhabitants of the shore of polar, temperate and tropical seas. Echiura comprise unsegmented, coelomate, bilaterally symmetrical and soft-bodied invertebrates. She would be glad to identify of echiurans collection from any region of the World Ocean. www.ibss.iuf.net /people/murina/echiura.html   (1046 words)

NationMaster - Encyclopedia: Lophotrochozoa The Sipuncula, sipunculid worms or peanut worms, are a phylum of marine worms with a tentacle surrounded mouth on a completely invertible head end. Classes and subclasses Class Polychaeta(paraphyletic?) Class Clitellata Oligochaeta- Earthwormsand others Acanthobdellida Branchiobdellida Hirudinea- Leeches Class Myzostomida Class Archiannelida(polyphyletic) Class Echiura The annelids, collectively called Annelida (from Latin annellus little ring), are a large phylum of animals, comprising the segmented worms, with about 15 000 modern species including the... The Ecdysozoa are a large group of protostomian animals, erected by Aguinaldo in 1997 primarily based on 18s rRNA data. www.nationmaster.com /encyclopedia/Lophotrochozoa   (937 words)

Complete mitochondrial genome sequence of Urechis caupo, a representative of the phylum Echiura | BMC Genomics, Volume ... This is the first description of a complete mitochondrial genome sequence of a representative of the phylum Echiura, that of the fat innkeeper worm, Urechis caupo. For the other seven cases, genes are separated by a single nucleotide, and in six of these, that nucleotide is a C. (The remaining case is a T.) The prevalence of C is consistent with the measured G-skew between the strands, although it is possible that this otherwise indicates some function of these nucleotides. This is the first description of a complete mitochondrial genome sequence of a representative of the phylum Echiura. bmc.ub.uni-potsdam.de /1471-2164-5-67/text.htm   (2583 words)

Mazon Creek Fossil Coprinoscolex The Mazon Creek fossil shown here is colloquially called a “leech”;, but is actually a member of the obscure Phylum Echiura, and are close relatives of the annelid worms. It is thought that the segmentation onserved in some fossils (as here) is the result of contraction of the skin due to the shock of burial. Echiura were initially regarded as annelids, were then excluded, but newer evidence suggests they are, in fact, annelids. www.fossilmuseum.net /fossils/Worms/Coprinoscolex-ellongimus/Coprinoscolex.htm   (122 words)

Research - Harvard In the Echiura, there are 142 putative species in 37 genera, 24 of these genera containing only 1 or 2 species, and only 4 genera have more than 6 species. At Harvard, my primary objective was to develop an expertise in the morphology and taxonomy of both Sipuncula and Echiura and re-evaluate the Echiura through as many type representatives for each of the genera available. I also also focussed more narrowly on questions relating to their population genetics or phylogeny within both groups, the primary result of this fellowship was the critique and re-evaluation of Echiura taxonomy at the generic level. www.biol.sc.edu /~coull_lab/staton/ab5.html   (355 words)

Evolutionary Biology - Molecular Phylogeny of the Polychaeta Polychaetes are currently classified into more than 90 families and lack a satisfactory phylogenetic hypothesis. The group lacked a higher level classification, with its position being uncertain with respect to the Oligochaeta, and the two doubtful phyla Vestimentifera and Echiura. Some of the main clades within the group were well supported, but the majority of basal nodes had very few synapomorphies. www.amonline.net.au /evolutionary_biology/research/projects/polych.htm   (352 words)

Science Biology/Flora and Fauna/Animalia/Echiura Echiura - Devolopment of the nervous system and phylogenetic implications - Immunohistochemical analysis (cLSM) of the development and organization of the nervous system in Echiura and the phylogenetic implications of these results. Introduction to the Echiura - Introduction to this small phylum, closely related to the Annelids, from UCMP Berkeley. Minor Invertebrate Phyla - Echiura - Echiurans are marine worms that burrow into mud or sand or live in empty shells. www.gy.com /Science/Biology/Flora_and_Fauna/Animalia/Echiura/index.htm   (215 words)

Lab 2 – Lopotrochozoa (10 Phyla) Echiura – The Echiura are also known as the “spoon worms.” There are 150 described species of Echiura that occur in marine habitats. Echiura occupy burrows in mudflats where they filter water and capture planktonic organisms with a mucous net created by their proboscis. Morphology: The Echiura are unsegmented worms with an extensible proboscis and small hooks on the posterior end. userwww.sfsu.edu /~efc/classes/biol170/lab/Laboratory-2.htm   (1534 words)

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