Porcupine Fish, the common name of a family of fish. Porcupine fish are from about 10 inches to 3 feet (25 to 90 cm) long, and are covered with sharp spines. They can inflate themselves by drawing air or water into a sac in their bodies. Porcupine fish are found in nearly all tropical and some temperate waters. They feed mainly on shellfish, which they crush with their strong teeth. North American species include the porcupine fish (for which the family is named), the balloonfish, and the burrfish. They are found along the Atlantic coast from New England south to Florida.

The pufferThe puffer is a type of porcupine fish that inflates itself by drawing in air or water.
Why Does a Porcupinefish Puff Up?

A porcupinefish inflates, or puffs up, to protect itself. The fish has flat, needlelike spines all over its body. If an enemy scares it, the porcupinefish swallows water and blows up like a balloon.

When a porcupinefish is scared, it puffs up to two or three times its normal size. It doesn’t get any longer, but it sure gets bigger around. Not only can its large size scare away an enemy, but its spines now stick straight out. Most enemies don’t dare touch the porcupinefish then. Once danger has passed, the fish shrinks to its normal size.

Porcupinefish are about 10 to 12 inches (25 to 30 centimeters) long and live in the warm waters of the Atlantic, Pacific, and Indian oceans. These fish eat snails, crabs, and sea urchins.

The porcupine fish is Diodon hystrix; balloonfish, D. holocanthus; burrfish, Chilomycterus schoepfi. All belong to the family Diodontidae.