question_answer 56)

  Using appropriate examples, differentiate between false and true body segmentation.

Answer:

                  Segmentation is the serial repetition of similar body parts along with the length of ananimal. The body of animals can be truely segmented or pseudo/false segmented. True segmentation is found in annelids, arthropods and some chordates. In this, there is alinear repetition of body parts and each repeated unit is called somite (metamere). In earthworms, the successive somites are essentially similar but they are dissimilar in different body regions of a crayfish or insect. Metamerism is conspicuous both externally and internally in annelids. Pseudo segmentation is seen when body is divided into number of pseudo segments which are independent of each other. Each segment is able to perform all the vital functionof body. Body grows by the addition of new segments from the anterior end, e.g., tapeworm.