Sawfish are a family of very large rays characterized by a long, narrow, flattened rostrum, or nose extension, lined with sharp transverse teeth, arranged in a way that resembles a saw. They are among the largest fish, with some species reaching lengths around . They are found worldwide in tropical and subtropical regions in coastal marine and brackish estuarine waters, as well as freshwater rivers and lakes. All species are critically endangered.
They should not be confused with sawsharks (order Pristiophoriformes) or the extinct sclerorhynchoids (order Rajiformes), which have a similar appearance, or swordfish (family Xiphiidae), which have a similar name but a very different appearance.
Sawfishes are relatively slow breeders and the females give birth to live young. They are generally harmless to humans, but can inflict serious injuries with the saw when captured and defending themselves.
Sawfish have been known and hunted for thousands of years, and play an important mythological and spiritual role in many societies around the world.
Once common, sawfish have experienced a drastic decline in recent decades, and the only remaining strongholds are in Northern Australia and Florida, United States. All five species are rated as critically endangered by the International Union for Conservation of Nature. They are hunted for their fins (to make shark fin soup) and for the use of other parts, including the teeth and rostrum, in traditional medicine. They also face habitat loss. They are protected in Australia, the United States, and several other countries, meaning that sawfish caught by accident have to be released, and violations can be punished with hefty fines.
Taxonomy and etymology
The scientific names of the sawfish family Pristidae and its type genus Pristis are derived from the .
Despite their appearance, sawfish are rays (superorder Batoidea). The sawfish family has traditionally been considered the sole living member of the order Pristiformes, but recent authorities have generally subsumed it into Rhinopristiformes, an order that now includes the sawfish family, as well as families containing guitarfish, wedgefish, banjo rays, and the like. Sawfish quite resemble guitarfish, except that the latter group lacks a saw, and their common ancestor likely was similar to guitarfish.
Anoxypristis contains a single living species that historically was included in Pristis, but the two genera are morphologically and genetically highly distinct. Today Pristis contains four living, valid species divided into two species groups. Three species are in the smalltooth group, and there is only a single in the largetooth group.
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Extinct (fossil) species
thumb|†[[Propristis|Propristis schweinfurthi]]
In addition to the living sawfish, there are several extinct species that only are known from fossil remains found around the world in all continents. or probably a junior synonym of the sclerorhynchoid Onchopristis. Indisputable sawfish genera emerged in the Cenozoic age about 60 million years ago, relatively soon after the Cretaceous–Paleogene mass extinction. Among these are Propristis, a monotypic genus only known from fossil remains, as well as several extinct Pristis species and several extinct Anoxypristis species (both of these genera are also represented by living species). Historically, palaeontologists have not separated Anoxypristis from Pristis. and Mesopristis,
The extinct order Sclerorhynchoidei had long rostra with large denticles similar to sawfishes and sawsharks. This feature was convergently evolved, recently proposed as 'pristification', and their closest living relatives are actually skates. While they are often called "sawfishes", the more accurate common name for sclerorhynchoids is "sawskates".
Appearance and anatomy
Sawfish are dull brownish, greyish, greenish or yellowish above, The underside is pale, The rostrum length is typically about one quarter to one third of the total length of the fish, The rostral teeth grow in size throughout the life of the sawfish and a tooth is not replaced if it is lost. In Pristis sawfish, the teeth are found along the entire length of the rostrum, but, in adult Anoxypristis, there are no teeth on the basal one-quarter of the rostrum (about one-sixth in juvenile Anoxypristis). The number of teeth varies depending on the species and can range from 14 to 37 on each side of the rostrum.