Pufferfish

Star puffer (Silke Baron / CC BY)

Pufferfish (Tetraodontidae) have the remarkable ability to inflate themselves with water to an enormous size when threatened. This behavior is supposed to discourage potential predators. Their skin is scaleless and elastic. Some species produce the poison tetrodotoxin which can be fatal to humans when taken up with food. Puffers range between 11 centimeters (4.3 inches, sharpnose puffer) and 120 centimeters (47 inches, star puffer) in length.

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This supplemental online resource accompanies the book Scuba Diving Hand Signals by Lars Behnke, available on Amazon.