Porcupine fish are commonly confused with its related Puffer fish, nevertheless porcupine fish have sharp spines on their bodies, this is a second defense mechanism, as the fish inflate the spines come out.
Ballon fishhas no spots on their fins.
How do porcupine and puffer fish inflate? when they feel threatened, they inflate their bodies by swallowing water, thereby becoming rounder - like a ball !, increasing in volumne and reducing the risk of being attacked.
Some species are poisonous.