A pufferfish is a saltwater and estuary fish in the family Tetraodontidae, which is further divided into 20 genera and approximately 150 species. Pufferfish are known by many names, including blowfish, globefish and swellfish. Many species of pufferfish are poisonous. The pufferfish also has a unique self-defense mechanism that enables it to enlarge its girth to more than three times its normal size, which gives the pufferfish its various names.
Most varieties are relatively small, ranging from three to 15 inches (7.5 to 39 cm) in length, although some species may reach up to 24 inches (60 cm). Their club-shaped bodies are covered with fine spines that make them appear spotted. They have pectoral fins on either side, as well as dorsal and belly fins located near a small tail. Their bulging eyes are forward-facing and can move independently of each other. The family name Tetradontidae refers to four large teeth in the upper and lower jaws.
Pufferfish are native to tropical waters. They prey upon crustaceans and mollusks by using their strong jaws and sharp teeth to crush the shells. They swim slowly because of their shape and fin configuration, so they rely on the puffing mechanism to ward off predators. The puffing mechanism works by means of a highly expandable stomach that allows it to fill with water or air, causing a balloon-like appearance. Some pufferfish are also able to change colors like a chameleon.
The poisonous pufferfish contains a neurotoxin called tetrodotoxin. The poison is concentrated in the liver, ovaries, eggs and, to some degree, the intestines and skin. Certain predators of the poisonous pufferfish are not affected by the toxins. Some varieties of pufferfish are naturally non-toxic, and some commercially-farmed pufferfish are specially bred to eliminate the toxins.
Pufferfish are known as "fugu" in Japan, where they are considered a dangerously edible delicacy. The city of Shimonoseki in Yamaguchi Prefecture is known for the commercial cultivation of fugu. In Japan, nearly 10,000 tons (8928.57 metric tons) of fugu are consumed each year.
A fugu meal in a restaurant can be quite expensive and usually consists of several dishes. The meal may include raw fugu sashimi, fugu-chiri soup and deep-fried fugu kara-age. Fugu should always be prepared by a trained, licensed fugu chef. The meal should be consumed slowly and if at any point numbness or tingling are felt in the lips and tongue, medical help should be sought immediately.