Biology 10+1, Animal Kingdom Chapter 4, CBSE, NCERT. Video Tutorial.
Through all members of Animalia are multicellular, all of them do not exhibit the same pattern of organisation of cells. For example, in sponges, the cells are arranged as loose cell aggregates, i.e., they exhibit cellularlevel of organisation. Some division of labour (activities) occur among the cells. In coelenterates, the arrangement of cells is more complex.