Tag Archives | Articles on Animals

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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Echinoderms: Classification, Habitat and Affinities

In this article we will discuss about Echinoderms:- 1. Taxonomic Retrospect of Echinoderms 2. Definition and Origin of Echinoderms 3. Classification 4. Phylogenetic Considerations 5. Research 6. Habit and Habitat 7. Size 8. Shape and Symmetry 9. Body Wall and Skeleton 10. Digestive System 11. Coelom 12. Haemal System or Blood Lacunar System 13. Excretory System 14. Nervous System 15. [...]

By |2016-05-27T11:31:15+00:00May 27, 2016|Phylum Echinodermata|Comments Off on Echinoderms: Classification, Habitat and Affinities
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