Jumat, 27 Agustus 2010

Introduction Porifera

A. Background
Sponges are animals of the phylum Porifera (Pore bearer). Their bodies consist of jelly-like mesohyl sandwiched between two thin layers of cells. While all animals have unspecialized cells that can transform into specialized cells, sponges are unique in having some specialized cells that can transform into other types, often migrating between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes, and the shapes of their bodies are adapted to maximize the efficiency of the water flow. All are sessile aquatic animals and, although there are freshwater species, the great majority are marine (salt water) species, ranging from tidal zones to depths exceeding 8,800 metres (5.5 mi).
It is important for us to learn about phylum porifera because it will be the basic for us to learn about the higher level of invertebrate. Furthermore, we will be able to improve our knowledge about the diversity of kingdom animalia. Hence, it will be efficient for us to do the experiment which was entitled "Phylum Porifera"


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