question_answer 1)

What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?

Answer:

The major difficulties in the classification of animals are on the followings lines (i) Some show cellular level of organization, some have tissue level and even some have organ system level of organization. (ii) Regarding symmetry, some are radially symmetrical, while some have bilateral symmetry. (iii) Some have open circulatory system, while others have closed type. (iv) Regarding digestion, some animals have extracellular digestion, while others have intracellular digestion. (v) In case of body cavity, some have true coelom, while others are pseudocoelomates. (vi) Regarding reproduction, some have only asexual reproduction, while others reproduce both by sexual and asexual means. So, these are difficulties that zoologists face in the classification of animals.