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gracieteoliveira [licensed for non-commercial use only] / Classe Cephalopoda. Cuvier, G. Second Mémoire sur l’organisation et les rapports des animaux à sang blanc, dans lequel on traite de la structure des Mollusques et de leur. Mollusks are divided into seven classes with most species residing in gastropoda . The class Cephalopoda is a remarkable group of mollusks.

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The evolution of the Scaphopoda and its implication for the systematics of the Rostroconchia Mollusca.

Gonoduct running towards anterior, between stomach and mantle, gradually running obliquely, from median line to right, crossing esophageal insertion; insertion on dorsal-right surface of kidney, just by side of local portion of esophagus. Hinge dorsal fold of mantle Fig.

Academic Press, London, cephalipoda Representationes Leger Modificar Modificar fonte Vider historia. The mantle is still continuous dorsally, showing no clear clue of valve separation except for a fold that builds the hinge Fig. Ciencias Marinas21 3: Alcide Dessalines d’ Orbigny Publisher: Evolution of the cephalopod head complex by assembly of multiple molluscan body parts: In scaphopods, Gadilida still remain circum-buccal ganglia, which is also found in some protobranchs such as nuculanids and partially in solemyids.

Early Cephlaopoda fossils from South Australia. Posterior mantle flap with a very thin layer of longitudinal muscles inserted in a ring of entire flap base, just posterior to longitudinal muscles origin in ventral half. The foot, in these cases, and as another indicative of homology, separates the mouth and respective appendages palps or captacula from the remaining pallial cavity.

As explained below, this paper is the result of a larger project related to a group of Bivalvia, of which some of the presently analyzed species are outgroups.


Tableau méthodique de la classe des Céphalopodes

Functional and phylogenetic significance of protecting periostracal structures in the Bivalvia Mollusca. The earliest bivalves and their Ordovincian descendants. Both longitudinal muscles ccephalopoda straight towards anterior, gradually crossing from ventral to lateral, coming away from one another Figs. Brazilian Journal of Biology67 4: Another feature that could support this node is pedal feeding in early juveniles; this feature is common to nuculids and most lamellibranchs Reid et al.

In this case, the umbrella-like foot is maintained as a Diasoma synapomorphy, with a single reversion in lamellibranchs node 9. Some points, however, are certainly broached in the discussion. Pair of cerebral ganglia more elongated laterally, possessing a single anterior nerve each Fig.

Loligo sp (lula)

Brazilian Marine Mollusks Iconography. In both Diasoma classes a clear tendency for ganglia to become distant from each other appears. This shell difference, allied to a relatively wide geographic distance and the glacial separation between that region and the south Atlantic coast of South America, are indicative of the reports from Chile and Peru that the species actually belongs to another, possible new species.

Despite this conservative approach, this concept is subject to change with further studies. Pair of lateral tooth with more irregular distal-medial tip, barely forming hooks. Devonian Dentalium martini Whitfield,is not a mollusk but a worm.

The main goal, instead, is to furnish another point of view and further argumentation to the still inconclusive relationships of bivalves and tusk-shells. Gills modified for filtering: Classification and evolution cdphalopoda the Bivalvia: Yonge ; Allen ; Starobogatov ; Morton, ; Morton et al. Invertebrate Biology4: As the homology between the gadilid terminal disk and the dentaliid umbrella-like foot tip is unclear, the gadilid state c,asse coded as absent here.

The evolution of the ligament systems in the Bivalvia. Posterior aperture with narrow slit in ventral surface Fig.


Introdução à classe: Scaphopoda | mollusca

In the presently considered outgroups monoplacophores and polyplacophores, the pallial cavity is cephalopodda a furrow which surrounds the foot. This molluscan branch is regarded to have diverged at the early Cambrian, bearing representatives with shells opening on both sides, and the digestive tube in a somewhat straight organization, i.

Yet characters 21 and 22 explore special features of the Diasoma classes, which are absent in the remaining ones.

The complete sequence and gene organization of the mitochondrial genome of the gadilid scaphopod Siphonodentalium lobatum Mollusca. Most basal mollusks, including the monoplacophorans, has narrow kidneys somewhat splayed along the haemocoel. Structure annexed to stomach: Pair of cephqlopoda ganglia located close to origins of foot protractor muscle Fig.

From protobranchs, Nuculoidea 1 speciesNuculanoidea 1 species and Solemyoidea 2 species were chosen. Anterior inhalant currents and pedal feeding in bivalves. Journal of Paleontology Pillucina, Wallucina and descriptions of two new genera and four new species. It is equally parsimonious to consider state 1 as a Diasoma synapomorphy node 1with a reversion in Gadilidae node 4or a convergence between Dentaliidae node 3 and Bivalvia node 5.

Rejection of Carboniferous Quasidentalium Shimansky,from the phylum Mollusca.

Foot and byssus Figs. It is important to emphasize that some studies on the phylogeny of scaphopods and bivalves have been produced in the last decades, mostly or totally based on molecular biology.

Aspects of the biology of a gutless species of Solemya Bivalvia: