Question

Octopus belongs to ______ phylum.
1. Hemichordata
2. Echinodermata
3. Arthropoda
4. Mollusca

Answer 1

Correct Answer - Option 4 : Mollusca

The correct answer is Mollusca

• Characteristics of Mollusca: 
  • Soft-bodied.
  • Bilaterally symmetrical.
  • Usually shelled having a mantle.
  • Ventral foot.
  • Anterior head.
  • Dorsal visceral mass.
• Octopus belongs to the class Cephalopods.

• Characteristics of Hemichordata:
  • ​Vermiform, solitary, or colonial enterocoelous coelomate.
  • Intra-epidermal nervous system.
  • Pre-oral with or without gill-slits.
  • Without typical nephridia.
  • Eg: Balanoglossus.
• Characteristics of Echinodermata:​
  • Enterocoelous coelomates with pentamerous radial symmetry.
  • Without distinct head or brain.
  • Having a calcareous endoskeleton.
  • A peculiar water vascular system of coelomic origin with podia or tube-feet projecting out of the body.
  • Eg: Starfish.
• Characteristics of Arthropoda:​
  • Bilaterally symmetrical.
  • Triploblastic, metamerically segmented animals.
  • With coelom which is reduced and modified.
  • Their body is covered externally in a chitinous exoskeleton
  • Their appendages are joined.
  • Eg: Crabs, lobsters, shrimp, spider, butterfly.
  • Arthropoda is currently the largest phylum.