piranha

A piranha or piraña (, , or ; , ) is one of a number of freshwater fish in the family Serrasalmidae, or the subfamily Serrasalminae within the tetra family, Characidae in order Characiformes. These fish inhabit South American rivers, floodplains, lakes and reservoirs. Although often described as extremely predatory and mainly feeding on fish, their dietary habits vary extensively, and they will also take plant material, leading to their classification as omnivorous. Etymology The name originates from the indigenous Tupi people and their respective Tupi language. It is formed from two words, meaning fish and meaning tooth; the same word is used by Indians to describe a pair of scissors. Another possible derivation is from , probably literally 'biting-fish'. In the mid 18th century the Portuguese merged the word into . Finally, the word may also come from the combination of 'fish' and 'cut' (which also meant 'bad' or 'devil' in Tupi-Guarani). Taxonomy and evolution Piranhas belong to the subfamily Serrasalminae, which includes closely related omnivorous fish such as pacus. Traditionally, only the four genera Pristobrycon, Pygocentrus, Pygopristis, and Serrasalmus are considered to be true piranhas, due to their specialized teeth. However, a recent analysis showed, if the piranha group is to be monophyletic, it should be restricted to Serrasalmus, Pygocentrus, and part of Pristobrycon, or expanded to include these taxa plus Pygopristis, Catoprion, and Pristobrycon striolatus. Pygopristis was found to be more closely related to Catoprion than the other three piranha genera. The total number of piranha species is unknown and contested, and new species continue to be described. Estimates range from fewer than 30 to more than 60.