In this article we will discuss about the embryonic development of egg and yolk in insects and birds. Egg: The eggs are generally spherical but eggs of insects are elongated and cylindrical. The eggs of some polychaetes, fishes and birds are oval in shape. The egg cells are covered by plasma membrane which is secreted by egg cytoplasm (ooplasm). The [...]
The following points highlight the five main types of symmetry seen in animals. The types are: 1. Asymmetrical Symmetry 2. Spherical Symmetry 3. Radial Symmetry 4. Biradial Symmetry 5. Bilateral Symmetry. Type # 1. Asymmetrical Symmetry: In some animals there are no body axis and no plane of symmetry, hence the animals are called asymmetrical. The amoeboid forms (e.g., Amoeba) [...]
The upcoming discussion will update you about the difference between Protozoa and Metazoa. Difference # Protozoa: 1. Protozoans are unicellular animals. 2. Protozoans are generally microscopic. 3. Acellular or body is not differentiated into cells. 4. Single cell can perform all sorts of functions like a complete multicellular organism. 5. Single cell is capable of independent existence. 6. Body of [...]