Pufferfish are a large family of saltwater fish consisting over a 100 distinct species. The various species of pufferfish are referred to by several common names such as balloonfish, blowfish, bubblefish, toadfish and sea squabs. Pufferfish are closely related to porcupine fish but do not have the same large, protruding external spines of the porcupine fish. Instead they have thinner spines which are hidden and only visible when they puff themselves up. Pufferfish are an extremely slow swimming, agile species of fish that utilizes all its fins when swimming. To compensate for this slow speed, it has also developed a unique defensive mechanism. When feeling threatened, a pufferfish will fill its elastic stomach with water until it expands to a large, almost globe-like shape. Pufferfish are also considered to be the second most poisonous vertebrae in the world and certain body parts of the fish are highly toxic to most other animals. Puffers come in shades of tan, brown, grey, black and white. In addition their bodies often display complex patterns of color and markings.