Fundamentals of Animal Classification
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Fundamentals of Animal Classification
Classification of Animals Non Chordates of Class 11
Levels Of Body Organization
Following are the different levels of organization in animals from simpler to complex state:
1. Protoplasmic grade – In this grade all life activities are confined within the boundaries of a single cell which is a structural and functional unit of life. e.g. Protozoa and other unicellular organism.
2. Cellular grade – It is a loose association or aggregation of cells that are functionally differentiated, e.g. sponges.
3. Tissue grade – An aggregation of cells which act in co-ordination. e.g. Cnidarians.
4. Tissue-organ grade – When tissues aggregate to form a particular organ. First appeared in platyhelminthes.
5. Organ system grade – When organs work together to perform some common function such as digestion, respiration, circulation etc. e.g., most of the higher animals.
