Describe the four different levels of organization in metazoans.

Explanation

The levels of organisation in matazoans are as follows:
1) Cellular level of organisation : It is the lowest level of organisaton among the metazoans and is exhibited by the sponges, Different types of cells are functionally isolated due to the absence of sensory and nerve cells. There is no uniformity of labor among the cells and they don.t form tissues.
2) Tissue level of organisation : This is the lowest level of organisation among the eumetazoans, exhibited by diploblastic animals like the cnidarians. In these animals the cells which perform the same function are arranged into tissues due to the presence of nerve cells and sensory cells.
3) Organ level of organisation : An aggregation of different kinds of tissues which is specialized for a particular function is called an organ. Organ Jevel of organisation is a further advancement over the tissue level in the evolution of levels of organisation. It is first time appeared in the members of platyhelminths.
4) Organ-system level: It is the highest level of organisation among the animals and is exhibited by triploblastic animals such as the flat worms, nematodes, annelids, arthropods, molluscs, echinodermates and chordates. High specilized sensory and nerve cells bring about a higher level of coordination and integration among the various organ systems to lead an efficient way of life.