How does locomotion take place in leech?

1.	How does locomotion take place in leech?
Answer» Solution :(a) Looping or crawling movement : Crawling movement is BROUGHT about by the CONTRACTION and relaxation of muscles . The two sukers serve for attachment during movement. (b)Swimming movement : Leeches swim very actively and perform undulating movement in water. (ii) Fossilization in plants : The process of formation of fossil in the rocks is called fossilization. 1. Petrifaction : Minerals like silica slowly penetrate in and replace the ORIGINAL organic tissue . This method can preserve hard and soft parts (e.g.) wood fossils . 2. Mold and Cast : A replica of a plant or animal is preserved in sedimentary rocks . when the organism get buried in sediment it is dissolved by underground water leaving a hollow depressin called Mold. It shows only the original shape and not the internal structure. Minerals or sediments fill the hollow depression and forms a cast . 3. Preservation : The entire plant may be preserved to protect from the orginism for decay . Ice or amber (tree sap) can be used for preservation. 4. Compression : When the organism dies , the hard parts settle at the bottom of the sea bed and are covered by sediment . The process goes on continuously and the fossils are formed. 5. Infiltration : The precipitation of minerals takes place which LATER on infiltrate the cell wall. The process is brought about by several mineral element such as silica, calcium carbonate and magnesium carbonate.

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