Archive | Metazoa

Characteristics of Protostomes and Deuterostomes

In this article we will discuss about the development characteristics of protostomes and deuterostomes. Protostomes: Developmental Characteristics: 1. Pattern of embryonic cleavage: Spiral cleavage pattern; the spiral cleavage is masked at the 6th cleavages (64-cell stage), e.g., Sipuncula, Echiura, Annelida, Pogonophora, Mollusca and some groups of Arthropoda (e.g., Myriapoda, Crustacea and Insecta except Chelicerata). 2. Fate of embryonic blastomeres: Determinate [...]

By |2016-05-27T11:31:31+00:00May 27, 2016|Metazoa|Comments Off on Characteristics of Protostomes and Deuterostomes
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Top 6 Theories Regarding the Origin of Metazoa

The following points highlight the top six theories regarding the origin of metazoa. The theories are: 1. Syncytial-Ciliate Theory 2. Colonial Flagellate Theory 3. Colonial Blastea and Planula Theories 4. Gastraea Theory 5. Monophyletic Origin of Metazoans 6. Polyphyletic Origin of Metazoans. 1. Syncytial-Ciliate Theory: The origin of metazoans probably took place through the growth, nuclear division and cellularisation of [...]

By |2016-05-27T11:31:16+00:00May 27, 2016|Metazoa|Comments Off on Top 6 Theories Regarding the Origin of Metazoa
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Coelenterata: General Characters, Tissues and Corals | Metazoa

In this article we will discuss about Coelenterata:- 1. History of Coelenterata 2. General Characters of Coelenterata 3. Classification 4. Tissues 5. Polyp and Medusa 6. Polymorphism 7. Corals. Contents: History of Coelenterata General Characters of Coelenterata Classification of Coelenterata Tissues of Coelenterata Polyp and Medusa of Coelenterata Polymorphism of Coelenterata Corals of Coelenterata 1. History of Coelentrata: Aristotle knew [...]

By |2016-05-02T10:38:13+00:00May 2, 2016|Metazoa|Comments Off on Coelenterata: General Characters, Tissues and Corals | Metazoa
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