CLASSE CEPHALOPODA PDF

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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Comparative morphology among representatives of main taxa of Scaphopoda and basal protobranch Bivalvia Mollusca. This study deals with detailed morphology and anatomy of 4 species of Scaphopoda and 5 species of protobranch Bivalvia.

Both classes are traditionally grouped in the taxon Diasoma, which has been questioned by different methodologies, such dlasse molecular and developmental. This study is developed under a phylogenetic methodology with the main concern cepnalopoda performing it in an intelligible and testable methodology. The analyzed Scaphopoda species came from the Brazilian coast and belong to the family Dentaliidae [ 1 Coccodentalium carduus; 2 Paradentalium disparile ] and Gadiliidae; [ 3 Polyschides noronhensisn.

These species represent the main branches of the class Scaphopoda. From protobranch bivalves, representatives of the families Solemyidae [ 5 Solemya occidentalisfrom Florida; S. Brazil], Nuculanidae cepnalopoda 6 Propeleda carpentieri from Florida], and Nuculidae [ 7 Ennucula puelchafrom south Brazil] are included. These species represent the main branches of the basal Bivalvia.

The descriptions on the anatomy of S. The remaining are included here, for which a complete taxonomical treatment is performed. Beyond these species, representatives of other taxa are operationally included as part of the ingroup indices are then shared with themas a procedure to test the morphological monophyly of Diasoma. The effective outgroups are 12 Neopilina Monoplacophora and 13 Hanleya Polyplacophora.

Although they are not the main goal of this paper, the taxa Scaphopoda and Bivalvia are supported by 8 and by 7 synapomorphies respectively. The taxon Protobranchia resulted paraphyletic. Both scaphopod orders resulted monophyletic.

The obtained cladogram is: Coccodentalium carduus – Paradentalium disparile Polyschides noronhensis – Gadila brasiliensis Solemya occidentalis – S. Scaphopoda; Bivalvia; Diasoma; Phylogeny; Morphology. Scaphopoda; Bivalvia; Diasoma; Filogenia; Morfologia. 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. As the information obtained with the comparative analyzes is interesting, and helps to answer some im portant questions on the Mollusca higher inter-relationship, it was organized as a separate paper.

The main intention is to furnish a comparative and phylogenetic scenario with a theoretical background only based on morpho-anatomy. This is certainly interesting for further analysis, since analyses for the past, present or future have been produced using other equally important methodologies. The relationship of the Classes Scaphopoda and Bivalvia has been fluid, and even their monophyly has been questioned in some nom-morphological approaches.

Nevertheless, as also explained below, both classes were grouped in the presently controversial taxon called Diasoma. 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.

This somatic conformation is adapted to an infaunal mode of life, and to deposit feeding.

Diasoma was, then, subsequently accepted and used in the current technical literature e. In the early s, the concept of Cephlopoda was relatively well established in every phylogenetic vision of the Mollusca.

However, another affinity for the Scaphopoda gradually appeared, approximating the taxon to the Gastropoda-Cephalopoda branch e. Two main approaches were responsible for this change of concepts: Both, which are explained in more detail below, gradually transferred Scaphopoda to Cyrtosoma.

The new point of view has persuaded more generic literature on Malacology e. Of course most of this controversial relationship of the Scaphopoda, whether it be related to the Bivalvia or Cyrtosoma classes, was stressed in early literature e. However, with the introduction of phylogenetic methodologies, the discussion becomes more intelligible. This methodology has been applied mainly in the last three decades; conversely, and despite this, the scaphopod affinities are still inconclusive.

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A summary of this conceptual history is provided cephalkpoda the recent literature cepgalopoda. As the data of early literature was already explored by those papers, the present paper is, then, mainly concerned with argumentation of papers produced in the last three decades. Some recent dephalopoda have directly or indirectly influenced analysis of the Scaphopoda relationship. Some combined molecular approaches have even demonstrated that scaphopods are related to a set grouping cephalopods and nonconchiferan aplacophorans, at the base of Mollusca Giribet et al.

Beyond samples from Florida, some species from other regions and other taxa were selected in order to provide ccephalopoda and outgroups for cepnalopoda analyses. As stated above, the dataset in this paper revealed to be autonomous from the study on the Floridian taxa, and is worth publishing separately. Despite the consideration of some species from Florida, this study reached results important enough for individual publication. Although the number of taxa studied here is equivalent to that found in most papers, above related, referent to molecular and ultrastructural aspects, the main objective is not to test the other methodologies, nor their importance for comparative approaches.

The main goal, instead, is to furnish another point of view and further argumentation to the still inconclusive relationships of bivalves and tusk-shells. Another argument is that morphology is an autonomous science, claxse even if its importance in phylogeny and taxonomy has been proven to be weak, morpho-anatomy of the animals still must be studied. The final result, if only morphology is applied in the phylogeny at higher levels, must be exposed and debated.

The present study has, subsequently, the objective of testing the relationship of a set of Scaphopoda and Bivalvia, themselves and with remaining main branches of Mollusca, for the first time based on holistic morpho-anatomy.

For this task, a set of species were selected and examined in the same sort of details. From Cepualopoda, two species of each cephaloposa branch were chosen – Dentaliida and Gadilida Scarabino, ; Steiner, From Bivalvia, one or two samples of the main branches of cephalopdoa taxa, i. From protobranchs, Nuculoidea 1 speciesNuculanoidea 1 species and Solemyoidea 2 species were chosen.

Lamellibranchs include an Arcidae and a Tellinidae. Representatives of other molluscan classes were also selected as outgroups, however, some of them, as explained below, were operationally analyzed as part of the ingroup. This providence is a method for testing monophylies Simone, a. Further investigation on the phylogenies of Bivalvia and Scaphopoda was not performed, as they already exist in csphalopoda, such as in Bivalvia: Steiner a ; of which data and concepts are hereby also applied.

Types of Mollusks ( Read ) | Biology | CK Foundation

Beyond the self-searched data, information from the literature was used to increase the dataset of characters. For Scaphopoda, the following papers, which dealt with anatomical aspects, are included: For Bivalvia, the following general papers are considered: Yonge ; Allen ; Starobogatov ; Morton, cephalopod Morton et al. These papers also bring comprehensive history of the classification and evolution of both classes that are not cepahlopoda here. Some points, however, are certainly broached in the discussion.

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

In those studies, morphology is not applied or is a secondary part of the dataset. This demonstrates that the morphology has not been properly evaluated, an impression that the present study has the objective of altering. As has been done for more general papers with phylogenetic approaches Simone,a, b,a, b,clase paper initiates with the systematic part, containing taxonomical treatment and morphological descriptions.

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Afterwards, a phylogenetic treatment is given, with presentation and discussion of the characters. This paper ends with a discussion of the obtained cladogram in the light of present knowledge, with further implications mainly in taxonomy and phylogeny.

A complete list of material examined cephaolpoda each species description. The comparative parameter related to increased width along scaphopod length is cephalopoea by the formula: This translates approximately to the rate of augment along the animal length, everything in mm.

Dissections were made by standard techniques, with the specimens under a stereomicroscope, immersed in fixative or seawater. Digital photos of all steps of the dissection were taken. All drawings were obtained with the aid of a camera lucida. The presented measurements were obtained from selected specimens, normally dissected; these specimens are labeled at the collection.

Octopus joubini Robson, – Taxonomy

Description of the first species in each higher taxon is the most complete. For the other species, the description is comparative and more focused on distinctions, then called “distinctive description”.

This measure is for decreasing cephhalopoda length of this volume and for optimizing the discussion. The same approach is taken in the figures.

The part of this paper related to comparative biology is performed under a phylogenetic cladistic methodology, which is the most practical and testable method. However, there is no intention to consider the analysis of this paper as “the phylogeny of Bivalvia” nor “of Scaphopoda”. Nevertheless, it is expected that the putative phylogenetic relationships among the species will remain even with the addition of more species, and that some taxonomical inferences can already be made.

Analysis was performed with the aid of the program Tree-Gardener Ramos, under a few modifications for Windows XP and Vistawhich basically is an interface for the program Hennig86 Farris, The algorithm used was “ie”. Another five species are outgroups, but they are operationally analyzed as part of the ingroup. This measure is for testing the monophyly of Diasoma; conversely, the indices are shared cephalopods these taxa. In the discussion of the character, a short descriptive sentence is given for each one, followed by plesiomorphic and apomorphic states and conditions in the most parsimonious hypothesis.

Several other characters were selected but excluded from this analysis, because their states were overlapping or purely autapomorphic. However, some autapomorphic states were maintained; this measure is based on the interest of the state or to test its importance. Study on two of the protobranchs considered herein are published elsewhere: Nuculanidae Propeleda carpenteri Dall, and a second Solemyidae Solemya occidentalis Deshayes, Some characters were introduced in order to organize outgroups, i.

However, the search for such characters was very superficial, sufficient only to cephalkpoda objective. In the Discussion, some terms are used to designate a collective set of taxa, with no taxonomical purpose.

Tableau méthodique de la classe des Céphalopodes

Some of them are “protobranchs” in apposition to “lamellibranchs”; the former refers to the para-phyletic bivalve taxon C,asse, the last to the remaining Bivalvia. The term “lamellibranch” sets the filibranchs and the eulamellibranchs and possibly the septibranchsi.

Abbreviations used in figures: