The Porcupinefish is a type of balloonfish or blowfish. When it feels threatened, it can balloon up to three times its normal size by drawing water into its abdomen.
Another defense mechanism is that most species of Porcupinefish are poisonous. Their internal organs contain a powerful neurotoxin - tetrodotoxin - that is 1,200 times more potent than cyanide. This poison seems to be produced by bacteria obtained from its diet on the reef, as Porcupinefish bred in captivity are not poisonous.
Porcupinefish also inflate themselves differently than Pufferfish. Porcupinefish inflate by taking tiny gulps of water into their stomach until the body is fully extended. Pufferfish, on the other hand, have a special sac that they fill with water when inflating their bodies. Get to see more here at: http://island-showcase.com/porcupinefish-supermarket-reef.html
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