ESPICULAS DE ESPONJAS PDF

Con forma de copa. Formas aplanadas y largas que recuerdan a una alfombra. Al respecto de esta estructura es necesario puntualizar lo siguiente: Los pinacocitos forman el pinacodermo que es como si se tratara de la epidermis en el resto de los animales, es decir, la piel o capa exterior de la esponja de mar. Son el principal soporte de la esponja de mar. Peces con esponjas de mar.

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Choanoflagellates, choanocytes, and animal multicellularity Manuel Maldonado Abstract. It is widely accepted that multicellular animals metazoans constitute a monophyletic unit, deriving From ancestral choanoflagellate-like protists that gave rise to simple choanocyte-bearing metazoans.

However, a re-assessment of molecular and histological evidence on choanoflagellates, sponge choanocytes, and other metazoan cells reveals that the status of choanocytes as a fundamental cell type in metazoan evolution is unrealistic. Rather, choanocytes are specialized cells that develop from non-collared ciliated cells during sponge embryogenesis. Although choanocytes of adult sponges have no obvious homologue among metazoans, larval cells transd rentiating into choanocytes at metamorphosis do have such homologues.

The evidence reviewed here also indicates that sponge larvae are architecturally closer than adult sponges to the remaining metazoans.

This may mean that the basic multicelular organismal architecture from which diploblasts evolved, that is, the putative planktonic archimetazoan, was more similar to a modern poriferan larva lacking choanocytes than to an adult sponge. Alternatively, it may mean that other metazoans evolved from a neotcnous larva of ancient sponges. Together, thcse features strongly suggest that the Porifera may have a longer and more complicated evolutionary history than traditionally assumed, and also that the simple anatomy of modern adult spongcs may have resulted from a secondary simplification.

This makes the idea of a neotenous evolution less likely than that of a larva-like choanocyte-lacking archimetazoan. From this perspective, the view that choanoflagellates may be simplified sponge-derived metazoans, rather than protists, emerges as a viable alternative hypothesis.

This idea neither conflicts with the available evi- dence nor can be disproved by it, and must be specifically re-examined by further approaches combining morphological and molecular information. Interestingly, several microbial lincages lacking choanocyte-like morphology, such as Corallochytrea, Cristidiscoidea, Ministeriida, and Mesomycetozoea, have recently been placed at the boundary between fungi and animals, becoming a promising source of information in addition to the choanoflagellates in the search for the unicellular origin of animal multicellularity.

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Espícula (biologia)

Nigore Spicular remains of fresh-water sponges Porifera. They also pointed to a relationship between this deposit and transgressive events prior to the studied formation. La sedimentation lacustre indicateur de changements des paleoenvironments aucours des Porifera, Metaniidae Volkmer-Ribeiro, On Metania spinata Carter, and Metania kiliani n. Corvospongilla seckti Bonetto and Ezcurra de Drago Likewise important are microscleres and megascleres, which are the spicules that make up the body of the animal. Kunth Tavares et al. The marked occurrence of this assemblage throughout the stratigraphic columns, comprising 25 layers characterized as spongofacies [Layers 5, 6, 9, 10, 11 and 14 from Section 1 Fig.

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¿Cómo es el cuerpo de las esponjas marinas?

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Esponja de mar: Características, partes, alimentación, reproducción y más.

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