Any fish belonging to the family Tetraodontidae, characterized by a rounded body that can be inflated as a defensive strategy when the animal is threatened by predators. Some species, including the Pacific fugu (Takifugu rubripes), contain lethal amounts of the neurotoxin tetrodotoxin in their internal organs. In spite of this, fugu is prepared by specially trained chefs and served as a delicacy in Japan and elsewhere. Pufferfish are remarkable for their highly compact genomes compared with other vertebrate species; for example, the fugu genome is about one-ninth the size of the human genome but is predicted to have more genes than humans. In 2002 this species became the second vertebrate species (after humans) to have a draft sequence of its genome published; it is now used as a reference organism in comparative genomics.