Three new sponge species have been recorded from the Qatari waters by a research team under Qatar University’s Environmental Studies Center (ESC). “These are the kidney-shaped sponge Chondrosia reniformis, the purse sponge Grantia compressa and the sponge Sycon ciliatum,” ESC director Dr Mohsin al-Ansi has said. Najat al-Omari and Noora al-Fardi have been credited with the retrieval of the sponge species from sediments in a recent study on organisms which live on, in, or near the seabed. “Sponges belong to the Kingdom Animalia, Phylum Porifera which comprises three living classes and one extinct class (Archaeocyatha, whose fossils are common in rocks from 530mn years ago but not after 490mn years ago),” Dr al-Ansi explained in an article in the latest issue of Alrkiat, the ESC bulletin. Sponges are primitive organisms characterised by pores through which they feed. They 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 maximise the efficiency of the water flow. All are sessile (not able to move about) aquatic animals and, although there are freshwater species, the great majority are marine (salt water) species, ranging from tidal zones to depths exceeding 8,800m. While most of the sponge species feed on bacteria and other food particles in the water, some host photosynthesising micro-organisms as endosymbionts (that lives within the body or cells of another organism) and these alliances often produce more food and oxygen than they consume. A few species of sponge that live in food-poor environments have become carnivores that prey mainly on small crustaceans. Sponges are filter feeders: water enters through the pores, the needed nutrients are extracted and the water with waste products expelled via an opening known as the osculum. Sponges form different shapes and vary in their structure. It is believed that there are 15,000 living sponge species worldwide, belonging to three classes, seven subclasses, 25 orders, 127 families and 682 valid genera. http://gulf-times.com/site/topics/article.asp?cu_no=2&item_no=301413&version=1&template_id=36&parent_id=16

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