question_answer 28)

  Which among the following is exclusively marine? (a) Porifera                         (b) Echinodermata          (c) Mollusca                        (d) Pisces

Answer:

  (b) Echinoderm at on the other hand are spiny skinned marine animals. Porifera consist of sponges which are aquatic animals which remain fixed to the bottom of She sea. Most sponges are marine but few fresh water forms are also seen like Spongilla  Mollusca are soft bodied unsegmented animals. Molluscs are marine as well as terrestrial forms. Pisces are found in both marine water, (e.g., dog fish) and freshwater (e.g., Rohu).