Tetraodontidae is a family of mostly marine and estuarine fish belonging to the order Tetraodontiformes. The family includes many familiar species which are variously called pufferfish, balloonfish, globefish, toadfish, toadies, puffers, blowfish, swellfish, sugar toads, and sea squab. They are morphologically similar to the closely related porcupinefish, which have large external spines that are only visible when the fish has puffed up. The scientific name is in reference to the four large teeth, fused into an upper and lower plate which are used for crushing the shells of mollusks and crustaceans, their natural prey.

Pufferfish are usually believed to be the second most poisonous vertebrates in the entire world, after the golden poison frog. Certain internal organs, such as the liver, and sometimes the skin, are highly toxic to most animals when they are eaten; nevertheless, the meat of some species is considered a delicacy within Japan, Korea, and China when they are prepared by chefs who know which part is safe to eat and in what quantity.

The Tetraodontidae contain at least 120 species of pufferfish in 19 different genera. They are most diverse within the tropics and relatively uncommon in the temperate zone and completely absent from cold waters. They are usually small to medium in size, although a few species can reach lengths exceeding 39 inches.

Many marine pufferfish have a pelagic or open ocean life stage. Spawning takes place after the males slowly push the females to the water surface or join the females that are already there. The eggs are spherically shaped and buoyant. Hatching takes place after about four days. The fry are tiny, but under magnification have a shape normally reminiscent of a pufferfish. They have a functional mouth and eyes, and must eat within a few days. Brackish water puffers might breed in bays in a similar manner to the marine species, or they might breed more like the freshwater species, in cases where they have moved far enough upriver.

Image Caption: White-spotted puffer (Arothron hispidus). Credit: National Oceanic and Atmospheric Administration/Wikipedia