Which of the following molluscan classes is characterized by a closed circulatory system, complex brain, highly developed eyes, and chromatophores for rapid color change?
Correct: C
The description points to the most advanced class within Phylum Mollusca, the Cephalopoda (e.g., squids, octopuses, cuttlefish).
- Cephalopods are unique among molluscs for possessing a closed circulatory system. Most other molluscs have an open circulatory system.
- They have highly developed nervous systems, including a complex brain, and often sophisticated camera-like eyes.
- They are also known for their remarkable ability to change color rapidly using chromatophores for camouflage, communication, and display.
Gastropoda (snails, slugs) have an open circulatory system, less developed nervous system, and no chromatophores for rapid color change. Bivalvia (clams, oysters) have an open circulatory system, no distinct head, and filter feeding. Polyplacophora (chitons) are primitive molluscs with an open circulatory system and less complex features.