CLASSE POLYCHAETA PDF

Annelida: Class Polychaeta Enter your search terms: The vast majority of the more than 8, known species of polychaete worms are marine; some, however, are found in fresh or brackish water. They are abundant from the intertidal zone to depths of over 16, ft 5, m. Their colors are often brilliant, and some species are iridescent. The class has usually been divided on the basis of mode of existence into two groups, the errantia and the sedentaria. Errant Polychaetes Errant polychaetes include actively crawling or swimming forms which may, however, also spend time in burrows or crevices, or under rocks on the seashore.

Author:Akinosida Tolkree
Country:Estonia
Language:English (Spanish)
Genre:Finance
Published (Last):16 February 2011
Pages:63
PDF File Size:8.5 Mb
ePub File Size:6.57 Mb
ISBN:420-5-39271-870-4
Downloads:50099
Price:Free* [*Free Regsitration Required]
Uploader:Mogami



Zulkicage Most authors accept the annelids as having three major classes: Nereis singularis Wesenberg-Lund, subjective synonym, junior homonym. Atlas of the errantiate polychaetous annelids from California. Parasitic on freshwater crustacea. Quarterly Journal of Microscopy Although in Phoronida and Brachiopoda the segments do not accumulate inside flasse larvae, there is nevertheless a rapid metamorphosis and a dramatic elongation of the metasoma.

Nuchal organ a transverse slit and not everted on basal prostomial ring. Losses must have occurred in Maldanidae and Arenicolidae. Most pplychaeta have a pair of coelomata body cavities in each segment, separated from other segments by septa and from each other by vertical mesenteries.

Eliminating workable preconceptions from science is not advocated here, but the production of theory that is contrary to known data is objectionable. There is no information on the function of these prostomial peaks, but find it reasonable to suppose that they have a tactile-sensorial function. A phylogenetic analysis of the Phreodrilidae Annelida, Oligochaeta with a description of a new species.

First two parapodia uniramous, with a digitiform prechaetal lobe and short, rounded, postchaetal lobe; dorsal cirrus absent, and ventral cirrus short. The uncini are sometimes distinguished from other hooked chaetae Tab. The issue of morphological homology. Although these groupings do not always represent polycaheta most widely accepted taxa in polychaete polychaeeta, these groups were chosen in order to reduce to a minimum the potential influence of paraphyletic taxa in the analyses.

The second is related to the origin of the Ecdysozoa. The effort of contemporary pattern cladists to reject aprioristic character interpretations isunderstandable, especially in view of the many mistakes and authoritative impositions of the past.

The body cavity in Nemertea may be considered an exaptation pre-adaptationsubsequently modified for other functions, such as providing an hydrostatic body skeleton, promoting the circulation of body fluids, producing space for the maturation of reproductive cells, etc. SarsiaOslo, 70 1: There seems to be good support for a taxon named Radialia, including bryozoans, phoronids, and deuterostomians. Dorsal cirrus from third parapodium, oval to rounded, inserted dorsolaterally on body wall far from parapodial base.

Here again, the simplistic coding of several typical polychaete characters as absent in the clitellates tends to push the clitellates towards the base of the annelids. Arthropod and annelid relationships re-examined, p. The gills of ppolychaeta and burrowers usually cluster around whichever end has the stronger water flow. Questidae — polychaetes with oligochaetoid morphology and development. According to Bartolomaeusthe uncinal chaetae may also be characterized by the fact that the microvilli of their chaetoblasts are completely withdrawn by the end of chaetogenesis, being replaced by short processes from the chaetoblast, that keep the uncinus claese to the follicle.

Evidences of this tagmatization pattern are clearly present in Owenia. Iste pagina esseva modificate le plus recentemente le 18 martio a Others abbreviations used in the material examined: In this case the biramous condition found in different lobopodian and arthropod clades would not be homologous.

Order Eunicida Free-moving; head with or classs appendages and eyes; proboscis with dorsal maxillae upper jaws of 1 to many paired pieces, a ventral pair of mandibles lower jaws more or less fused along the median line, and a pair of embedded maxillary carriers; parapodia single-lobed, often with many aciculae needlelike structures ; size, minute to 3 m; examples of genera: They also have parapodia for locomotion.

Marine annelids may claxse for over one-third of bottom-dwelling animal species around coral reefs and in tidal zones. I pplychaeta, 8sometimes also involving the first metamere, are derived conditions in Metameria.

Maybe a similar embryonic shift in position has also occurred from the prostomial palps of Pogonophora to the peristomial mesocoelic lophophores of the Radialia Ax, On the microanatomy of the supraesophageal ganglion of some amphinomids Polychaeta Errantiawith further discussion of the innervation and homologues of the polychaete palps.

Respiratory pigment is also dissolved in the blood plasma. Nevertheless, as discussed poychaeta, homologies between the anterior regions of Polychaeta claswe Ecdysozoa need further study. Glycera boeggemanni new species Figures Material examined Type Material: The variations found by this author in the opening angle of both rami at the base, and also in relation to the length of the prechaetal lobe, led him to designate G.

Annotated classification The following classification incorporates the views of several authorities. The same appears to be true for the rings of the proboscideal papillae; i.

Related Posts.

LEGILE TERMODINAMICII PDF

Annelida: Class Polychaeta

Zulkicage Most authors accept the annelids as having three major classes: Nereis singularis Wesenberg-Lund, subjective synonym, junior homonym. Atlas of the errantiate polychaetous annelids from California. Parasitic on freshwater crustacea. Quarterly Journal of Microscopy Although in Phoronida and Brachiopoda the segments do not accumulate inside flasse larvae, there is nevertheless a rapid metamorphosis and a dramatic elongation of the metasoma.

DELL S2409W PDF

Polychaeta

Nell A repetition of structures thus seems to precede both the origin of the mesodermic body cavities and the origin of the mesodermic metameres. Review of shell reduction and loss in traditional and phylogenetic molluscan systematics, with experimental manipulation of negative gain character. Annelid — Wikipedia Bristles and segmentation evident. I60classw very similar to that found in some groups of Enterocoela e.

DECONT 300 PDF

.

M_O_R GUIDE PDF

.

Related Articles