Category: B.Sc II

Pearl is only gem stone which is produced by living animals. Pearl formation is a biological process in which pearl is formed by living animals against an irritant in the body of Oysters. The most productive Oyster is Pinctada vulgaris. The pearl develop in between shell and mantle of oyster. The layers of nacre develop into the pearl. It is made up of calcium carbonate and chonchiolin. The pearl may be natural and artificial. The peal culture industry is developed in Japan. It may be white, black, grey, red, green and blue in colour. The black coloured pearl is most rare and precious. It is used in jewelry.

This video is about digestive system. Digestion occurs through this system. Alimentary canal and digestive glands are important parts of this system.