UPSC Prelims 2014 Question

Among the following organisms, which one does not belong to the class of other three? a) Crab

Explanation: 

• Crabs belong to the category of crustaceans while Mite, Spider and Scorpion belong to the category of Arachnids.
  
  
• Crustaceans range in size from the Japanese spider crab, which can grow to more than four meters (13 feet), to tiny, microscopic copepods.
  
  
• All living arthropods have two key characteristics in common: hard exoskeletons and legs with joints. That last should come as no surprise. Arthropod means “jointed foot” in Greek.
  
  

Therefore, option (1) is the correct answer. 

Subject: Environment | Plant and Animal Anatomy