Question

An organism shows radial symmetry and an exoskeleton. It would be classified into

• A. Arthropoda
• B. Cnidaria
• C. Echinodermata
• D. Mollusca

Answer 1

Answer: (C)

Echinodermata

An organism showing radial symmetry and an exoskeleton would be classified into Echinodermata.

Echinoderms are characterized by radial symmetry, several arms radiating from a central body. The body actually consists of five equal segments, each containing a duplicate set of various internal organs.

Characteristics:

• Free-living exclusively marine forms.
  
• Adults are radially symmetrical while larvae are bilaterally symmetrical.
  
• The body is represented by a central disc covered by ossicles with spines called pedicellaria.
  
• The disc may bear extensions called arms.
  
• The digestive system is complete.
  
• A unique ambulacral or water vascular system is present.
  
• Tube feet are present for locomotion and respiration. Tube feet are extended and retracted by variation in hydraulic pressure of the fluid in them and contraction of their muscles.
  
• The nervous system has a central nerve ring with five radiating nerves.
  
• Reproduction is sexual. Sexes are separate. Development is indirect.
  
• Show the very high power of regeneration.