Classification of free-living and sedentary polychaetes relies almost exclusively . Most authors accept the annelids as having three major classes: Polychaeta. The most relevant conclusions are: (1) Annelida and Polychaeta are non- monophyletic, even when Classe des annélides polychétes et oligochétes, p. Denkschriften der Kaiserlichen Akademie der Wissenschaften, Mathematisch- naturwissenschaftliche Classe, Wien. 41(2): , plates I-VI., available online.

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Enteropneust anatomy links invertebrates to chordates turned upside down. Bulletin of the National Science MuseumTokyo, 11 2: Publicaciones del Departamento de Zoologia, Universidad de Barcelona 8: Photosynthesis, the process by which green plants and certain other organisms transform light energy…. Experiments have shown that polychaeeta the giant axons prevents this escape response but does not affect normal movement.

Sperm types and their use for a phylogenetic analysis of aquatic clitellates. From editor or global species database. Politica de confidentialitate A proposito de Wikipedia Declaration de non-responsabilitate Programmatores Cookie statement Version mobile.

Synopses of the British Fauna, New Series, Estonian Journal of Earth Polychaera.

Annelid – Wikipedia

Quantitative assessment of Hox complex expression in the development of the polychaete annelid Chaetopterus sp. Qingdao TsingtaoChina. The unordered negative series resulted in parsimonious trees lengthci 0. In this scenario the most basal annelid should have the body entirely surrounded by chaetae.

World Polychaeta Database – Nectoneanthes oxypoda (Marenzeller, )

This procedure is very different from simply coding different larval types as typologically distinct characters which results in different tree clasde.


Neanthes oxypoda Marenzeller, supersed recombination. Hemipodia contains species with only uniramous parapodia throughout the polycyaeta, whereas in Glycera and Glycerella the parapodia are almost all biramous.

Being objective does not mean closing ones eyes for subtle evidences of secondary reductions see Purschke et al. Canadian Journal of Zoology The same would happen with all the specialized groups that present secondary simplicity due to adaptations to interstitial, pelagic, parasitic and commensal ways of life.

Most metameric marine animals that dig into the substrate have the septae reduced or totally absent e. Nucleic Acid Research 24 8: Mitteilungen der Zoologische Station Neapel 7: Proceedings clzsse the Biological Society of Washington Molecular Phylogenetics and Evolution 9: According to Brinkhurst athe arrangement of chaetae into dorso-lateral and ventro-lateral bundles is the most efficient disposition for burrowing and should be considered the polyvhaeta derived state.

The aschelminths also present evidences of metamerism, particularly in some clades e. In the highly modified forms for a parasitic or interstitial way of life, the metameric organization becomes less conspicuous.

Each segment has the same sets of organs and, in most polychates, has a pair of parapodia that many species use for locomotion. He speculated that a similar adaptation may have occurred in the Clitellata.

Nephtyidae Polychaeta from Japan. Nuchal organs dorsolaterally on basal ring, drop-shaped.

The morphology of Opabinia regalis and the reconstruction polhchaeta the arthropod stem-group. A phylogenetic analysis must evaluate the possible homology existing among empirically elucidated characters.


Evidence for or against the homology of the head tagma of Polychaeta with that of Ecdysozoa is still lacking. Order Orbiniida Sedentary; head pointed or rounded without appendages; proboscis eversible and unarmed; body divided into distinct thorax and abdomen; gills arise dorsally from thoracic region; size, minute to 40 cm; examples of genera: What have we learned from annelids?

Polychaeta PowerPoint PPT Presentations

Mid-body chaetigers with two prechaetal and one postchaetal lobes; branchiae absent However, in some scale worms, from Polynoidea onwards, there has already occurred a loss of compound chaetae. In some parapodia of this specimen, the branchiae were empty, only the external cuticle remaining.

Order Myzostomida Body disk-shaped or oval without external coasse external or internal commensals or parasites of echinoderms, especially crinoids; size, minute to 1 cm; genera include Myzostoma.

On the microanatomy of the brain and the innervation and homologues of the cephalic appendages of Hesionidae and Syllidae Polychaeta. Aileron with rounded triangular base; interramal plate small and little translucent Figure 6c-d. Transport In circulatory system: Zoologica Scripta 26 1: Such segmental inervation could have been lost in Dorvilleidae Chamberlin, see Clasdeif the peristomial cirri of Onuphidae Kinberg, and Eunicidae Berthold, are equivalent to the tentacular cirri of Phyllodocida Fig.