Arthropoda, Mollusca and Echinodermata · Zoology

Which class of Mollusca is characterized by a closed circulatory system and high intelligence?

  1. Gastropoda
  2. Bivalvia
  3. Cephalopoda
  4. Polyplacophora
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Correct answer: Cephalopoda

Cephalopods (octopuses, squids, cuttlefish, nautiluses) are the most neurologically advanced molluscs. They are the only members of the phylum with a closed circulatory system, which supports the high oxygen demand of their active, predatory lifestyle and complex nervous systems.

Difficulty: Medium Question 6 of 20

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