Question

Which one has an open circulatory system?
1. Sea squirt

2. Cockroach

3. Earthworm

4. Prawn

5. Silverfish

6. Snail

7. Squid

• A. 2, 4, 6
• B. 1, 2, 4, 6
• C. 3, 4, 5, 7
• D. 2, 4, 5, 6
• E. 1, 2, 3, 4, 5, 7

Answer 1

The correct option is D 2, 4, 5, 6

• Ascidia (sea squirt) is a genus of tunicates that belongs to the subphylum Urochordata within phylum Chordata. All the chordates have a closed circulatory system (blood flows inside blood vessels).
• All members of the arthropods have an open circulatory system. Cockroach, Prawn, Silverfish belongs to this phylum.
• The snail (molluscan) has an open circulatory system with a two-chambered heart.
  
• Squid belongs to the Echinodermata that has a closed circulatory system.

Hence, the correct answer is option D.