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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Annelid – Wikipedia

These may correspond to the peristomial labiae or even to the polychqeta papillae of the Polyfhaeta. Canadian Journal of Zoology 66 Canadian Journal of Zoology 74 Glycera tesselata Grube Figure 13 Glycera tesselata Grube Order Archiannelida Minute, primitive, with ciliated epidermis; prostomium small, with or without appendages; parapodia absent; septa reduced or absent; size, minute. Invertebrate Biology 2: Acta Zoologica ;olychaeta, Stockholm, The first tentacular cirri in Nereididae, although having neither chaetae nor parapodia, should not be interpreted as non-metameric.

For Clark, the origin of the coelom is linked to the evolution of a burrowing way of life. In the mollusk phylum, clams of the genera Arca and Barbatia have numerous tiny compound eyes, each with up to a hundred ommatidia, situated around their mantles. Cahiers de Biologie marine 41 1: Microscopic anatomy of invertebrates.

Similar losses occur in the terrestrial polychaetes Purschke; Purschke et al. Canadian Journal of Zoology 60 5: Form and function External features Internal features Tissues and fluids Nervous system Digestive system Excretory system Respiratory system Circulatory system Hormones Evolution and paleontology Classification Distinguishing taxonomic features Annotated classification Critical appraisal.

Glycera brevicirrissyntype, ZMB Q. Polychata, the pharynx is strongly sclerotized and has ridges in these taxa Gustafson Tab. Coloration yellowish, with brownish pigments on dorsum, as transverse bands.


Some polychaetes breed only once in their lives, while others breed almost continuously or through several breeding seasons. It is not until the early Ordovician that the first annelid jaws are found, thus polchaeta crown-group cannot have appeared before this date and probably appeared somewhat later.

The pharynx in many metamerians may contain cuticular specializations such as mandibles and cuticular ridges Gustafson ; Fauchald ; Orensanz Leeches often have an eversible proboscis, or a muscular pharynx with two or three teeth.

Archives del Institut de Biochemie und Physiologie This led Orrhage a to reject the phylogenetic proposal of Dales A possible homology between the cephalic appendages of Polychaeta and the mesocoelic appendages of Enterocoela is still controversial. Annotated classification In polychatea The first pair of tentacular cirri of the Nereididae should be a step towards total cephalization from a state similar to other classse cirri.

A predatory habit can also be assigned to that level. These advantages have attracted the attention of engineers.

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He speculated that a similar adaptation may have occurred in the Clitellata.

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A Cambrian gilled lobopod from Greenland. Family Glyceridae Grube, Filo Annelida – Filo Annelida I.

Sipunculapreviously a separate phylum. The difference is that protonephridia combine both filtration stages in the same organ, while metanephridia perform only the second filtration and rely on other mechanisms for the first — in annelids special filter cells in the walls of the blood vessels let fluids and other small molecules pass into the coelomic fluid, where it circulates to the metanephridia.

As in arthropodseach muscle fiber cell is controlled by more than one neuronand the speed and power of the fiber’s contractions depends on the combined effects of all its neurons. Maybe this is partially due to the doubts concerning the phylogenetic position of the Tardigrada within the Metazoa sometimes displaced to the base of the bilaterians, within the old Pseudocoelomata Hyman, This led Balavoineto develop the idea that Platyhelminthes are highly modified coelomates.


Enumeratio Annulatorum, quae in itinere per Indiam occidentalem et Americam centralem annis suscepto legit cl. Glycera unicornis Savigny Report on the Annelids. A single pygidial cirrus represents an autapomorphy of Nephtyidae Dayand additional peg-like appendages are autapomorphic for Eunicidae Fauchald a, b. In the glaciated areas of North America, for example, almost all native earthworms are thought to have been killed by the glaciers and the worms currently found in those areas are all introduced from other areas, primarily from Europe, and, more recently, from Asia.

Placement of annelids within orders has been difficult because of the tremendous diversity in structure and specialization in habitat, especially in the polychaetes. Up to 6 simple capillary notochaetae and 26 compound spinigerous neurochaetae Figure 8g. The most generalized parapodium in our analysis has a neuropodium more developed than the notopodium “projecting neuropodia” Tab.

Vergleichende anatomische und ultrastrukturelle Undersuchungen ventraler Pharynxapparate bei Polychaeten und ihre phylogenetische Bedeutung.

Nevertheless, Sigalionoidea, Polynoidea, Spionida, and Paraonida remain paraphyletic. Nearly all polychaetes have parapodia that function as limbs, while other major annelid groups lack them.