QUE SIGNIFIE GASTRAEA EN ANGLAIS
Urmétazoan
L'Urmétazoan est l'hypothétique dernière ancêtre commun de tous les animaux. C'était sans aucun doute marin, mais au-delà de cela, sa forme est difficile à déterminer; Cinq hypothèses différentes ont été avancées, et la discrimination entre elles est difficile car les relations de phyla animal ne sont pas totalement résolues. Les biologistes considèrent que les animaux sont issus d'un eucaryote flagellé. Leurs parents vivants les plus proches sont les choanoflagellés, les flagellés collés qui ont une morphologie similaire aux choanocytes de certaines éponges. Les études moléculaires placent les animaux dans un supergroupe appelé opisthokonts, qui incluent également les choanoflagellés, les champignons et quelques petits protistes parasitaires. Le nom provient de l'emplacement postérieur du flagelle dans les cellules mobiles, comme la plupart des spermatozoïdes animaux, tandis que d'autres eucaryotes ont tendance à avoir des flagelles antérieurs.
définition de gastraea dans le dictionnaire anglais
La définition de gastraea dans le dictionnaire est une forme primitive à double paroi en forme de sac dont l'existence est suggérée par Haeckel; La théorie gastraea suppose que tous les animaux descendent de cette forme primitive.
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10 LIVRES EN ANGLAIS EN RAPPORT AVEC «GASTRAEA»
Découvrez l'usage de
gastraea dans la sélection bibliographique suivante. Des livres en rapport avec
gastraea et de courts extraits de ceux-ci pour replacer dans son contexte son utilisation littéraire.
1
Progress in Invertebrate Zoology
The double-layered form, with Urmund (blastopore) and gastral cavity (
archenteron), represents the gastrula stage and is known as the hypothetical
gastraea in the Metazoan ancestor. The gastraea theory was first put forward by
Ha'ckel.
The gastraea hypothesis suggests that the primitive nature of sponges and
coelenterates lies in their persistence at this diploblastic gastrula level. An
extension of the gastraea hypothesis is that an important body cavity of most
metazoans, the ...
Monroe W. Strickberger,
2005
3
Modern Text Book of Zoology: Invertebrates
(4) Endoderm is fundamentally produced by imagination, all other methods being
secondary modifications of invagination. 2. Support. Haeckel's Gastraea Theory
about ancestry of the Metazoa is mainly based on the embryological evidence.
4
Individual Development and Evolution: The Genesis of Novel ...
But the low animal forms which constitute the ancestral line between the
unicellular amoeba and the gastraea, and further between the gastraea and the
ascidian form, can only be approximately conjectured with the aid of comparative
...
5
Invertebrate Relationships: Patterns in Animal Evolution
One variant of gastraea theories that does avoid some of the problem areas has
recently been advanced by Nielsen & N¢rrevang (1985). They suggest that a
common monociliate gastraea stock gave rise directly to Cnidaria, and also via a
...
6
The Evolution of Man (Complete)
Justasthe countless species ofthe Metazoa do actuallydevelop in the
individualfrom the simple embryonicformofthe gastrula, so they
havealldescended inpast time from thecommon stemformofthe Gastraea. In this
fact,andthe fact we have ...
Ernst Heinrich Philipp August Haeckel
Gastraea hypothesis The gastraea hypothesis was proposed by Ernst Haeckel,[2]
shortly after his work on the calcareous sponges. He proposed that this group of
sponges is monophyletic with all eumetazoans, including the bilaterians.
8
Biology Takes Form: Animal Morphology and the German ...
Those forms which were repeated in otherwise widely different types were much
more likely to represent the original state than a later interpolation. This is the
basis for Haeckel's faith in the existence of the ancient gastraea: since he found
the ...
This theory is known as the Gastraea Hypothesis. Today, the Planula Hypothesis,
a variant of the Gastraea Hypothesis, is more popular, but the problems remain
the same as for the Gastraea Hypothesis of Ernst Haeckel (figure 5.5). Using the
...
10
Ontogeny and Phylogeny
Organs or Ancestors: The Transformation of Haeckel's Heterochrony Many have
traced the demise of Haeckel's theory to the inadequacy of his gastraea — that "
lean animal-specter"3 — as a satisfactory ancestor for all metazoans; or rather to
...
ACTUALITÉS CONTENANT LE TERME «GASTRAEA»
Découvrez de quoi on parle dans les médias nationaux et internationaux et comment le terme
gastraea est employé dans le contexte des actualités suivantes.
Acoel development indicates the independent evolution of the …
a, Hypotheses based on a simultaneous evolution of mouth and anus (top) either start with a pelagic hypothetical ancestor (gastraea and ... «Nature.com, sept 08»