Tetraodontidae is a family of marine and freshwater fish in the order Tetraodontiformes. The family includes many familiar species variously called pufferfishes, puffers, balloonfishes, blowfishes, blowers, blowies, bubblefishes, globefishes, swellfishes, toadfishes, toadies, botetes, toadle, honey toads, sugar toads, and sea squabs. They are morphologically similar to the closely related porcupinefish, which have large external spines (unlike the thinner, hidden spines of the Tetraodontidae, which are only visible when the fish have puffed up). The family name comes from Ancient Greek τετρα- (tetra-), meaning "four", and ὀδούς (odoús), meaning "tooth", referring to the four teeth of the type genus Tetraodon. The majority of pufferfish species are toxic, with some among the most venomous vertebrates in the world. In certain species, the internal organs, such as the liver, and sometimes the skin, contain mucus tetrodotoxin, and are highly toxic to most animals when eaten; nevertheless, the meat of some species is considered a delicacy in Japan (as 河豚, fugu), Korea (as 복, bok, or 복어, bogeo), and China (as 河豚, hétún) when prepared by specially trained chefs who know which part is safe to eat and in what quantity. Other pufferfish species with nontoxic flesh, such as the northern puffer, Sphoeroides maculatus, of the Chesapeake Bay, are considered a delicacy elsewhere.
Morphology
Pufferfish are typically small to medium in size, although a few species such as the Mbu pufferfish can reach lengths greater than 50 cm (20 in). Tetraodontiformes, or pufferfish, are most significantly characterized by their four beak-like teeth – hence the name combining the Greek terms "tetra" for four and "odous" for tooth. Each of the top and bottom arches is fused together with a visible midsagittal demarcation, which are used to break apart and consume small crustaceans. The lack of ribs, a pelvis, and pelvic fins are also unique to pufferfish. The notably missing bone and fin features are due to the pufferfish' specialized defense mechanism, expanding by sucking in water through an oral cavity. Pufferfish can also have many varied structures of caltrop-like dermal spines, which account for the replacement of typical fish scales, and can range in coverage extent from the entire body, to leaving the frontal surface empty. Tetraodontidae typically have smaller spines than the sister family Diodontidae, with some spines not being visible until inflation.
Taxonomy The Tetraodontidae contains 193 to 206 species of puffers in 27 or 28 genera:
In addition, the following fossil genera are known:
†Archaeotetraodon Carnevale & Santini, 2006 †Eotetraodon Tyler, 1980 †Leithaodon Carnevale & Tyler, 2015
Evolution The tetraodontids have been estimated to have diverged from diodontids between 89 and 138 million years ago. The four major clades diverged during the Cretaceous between 80 and 101 million years ago. The oldest known pufferfish genus is Eotetraodon, from the Lutetian epoch of Middle Eocene Europe, with fossils found in Monte Bolca and the Caucasus Mountains. The Monte Bolca species, E. pygmaeus, coexisted with several other tetraodontiforms, including an extinct species of diodontid, primitive boxfish (Proaracana and Eolactoria), and other, totally extinct forms, such as Zignoichthys and the spinacanthids. The extinct genus, Archaeotetraodon is known from Miocene-aged fossils from Europe. The following cladogram is based on a 2013 analysis of Tetraodontid mitogenomes:
Distribution They are most diverse in the tropical zone, relatively uncommon in the temperate zone, and completely absent from cold waters.
Ecology and life history Most pufferfish species live in marine or brackish waters, but several tropical genera, comprising about 35 species, spend their entire lifecycles in fresh water. These freshwater species are found in disjunct tropical regions of South America (Colomesus asellus and Colomesus tocantinensis), Africa (six Tetraodon species), and Southeast Asia (Auriglobus, Carinotetraodon, Dichotomyctere, Leiodon and Pao). Pufferfish diets can vary depending on their environment. Typically, their diet consists mostly of algae and small invertebrates. They can survive on a completely vegetarian diet if their environment is lacking resources, but prefer an omnivorous food selection. Larger species of pufferfish are able to use their beak-like front teeth to break open clams, mussels, and other shellfish. Some species of pufferfish have also been known to enact various hunting techniques ranging from ambush to open-water hunting.
Natural defenses
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