Largetooth sawfish

Historically, the taxonomy of P. pristis, in relation to P. microdon (claimed range: Western Indo-Pacific) and P. perotteti (claimed range: Atlantic and Eastern Pacific), has caused considerable confusion; evidence published in 2013 revealed that the three are conspecific, as morphological and genetic differences are lacking. As a consequence, recent authorities treat P. microdon and P. perotteti as synonyms of P. pristis; based on genetic analyses of NADH-2 genes, there are three main clades of P. pristis: Atlantic, Indo-West Pacific and East Pacific. ==Description==

(P. zijsron; middle) and knifetooth sawfish (Anoxypristis cuspidata; bottom). Notice especially the width of the saw, the teeth on the saw, the shape of the tail and pectoral fins, and the position of the dorsal fin compared to the pelvic fins The largetooth sawfish may mature to in total length, A sawfish caught in 1951 near Galveston, Texas, was documented on film but not measured; this fish has been estimated to be of similar size. Today, most individuals are far smaller and a typical length is . The largetooth sawfish is easily recognized by the forward position of the dorsal fin with its leading edge placed clearly in front of the leading edge of the pelvic fins (when the sawfish is seen from above or the side), the relatively long pectoral fins with angular tips, and the presence of a small lower tail lobe. In all other sawfish species the leading edge of their dorsal fin is placed at, or behind, the leading edge of the pelvic fins, and all other Pristis sawfish species have shorter pectoral fins with less pointed tips and lack a distinct lower tail lobe (very small or none). The rostrum ("saw") of the largetooth sawfish has a width that is 15–25% of its length, which is relatively wide compared to the other sawfish species, and there are 14–24 equally separated teeth on each side of it. The proportional rostrum length also varies with age, with average being around 27% of the total length of the fish, Individuals in freshwater may have a reddish colour caused by blood suffusion below the skin. The underside is greyish or white. ==Distribution and habitat==

to the Caribbean and the Gulf of Mexico. Its East Pacific range was from Peru to Mazatlán in Mexico. A parasitic flatworm, Dermopristis paradoxus, is commonly found on the skin and lining of the mouth and exclusively in Australian waters on the largetooth sawfish. The flatworm has been discovered to have a male reproductive system that lacks the copulatory organ. Adults are primarily found in estuaries and marine waters, to a depth of and dwarf sawfish (P. clavata). Largetooth sawfish from the population in Lake Nicaragua appear to spend most, if not all, of their life in freshwater, In captivity they are known to be agile (even swimming backwards), have an unusual ability to "climb" with the use of the pectoral fins and they can jump far out of the water; a individual jumped to a height of . It has been suggested that this may be adaptions for traversing medium-sized waterfalls and rapids when moving upriver. They are generally found in areas with a bottom consisting of sand, mud or silt. The preferred water temperature is between , and or colder is lethal. ==Behavior and life cycle==

The largetooth sawfish's maturity is reached once a length of about is attained, at roughly 7–10 years old. There are 1–13 (average 7) young in each litter, which are long at birth. and this mostly involves young individuals that are up to long. Occasionally, young individuals become isolated in freshwater pools during floods and may live there for years. The potential lifespan of the largetooth sawfish is unknown, but four estimates suggested 30 years, 35 years, 44 years, and 80 years. The largetooth sawfish is a predator that feeds on fish, molluscs and crustaceans. The "saw" can be used both to stir up the bottom to find prey and to slash at groups of fish. Sawfish are docile and harmless to humans, except when captured where they can inflict serious injuries when defending themselves with the "saw". ==Conservation==

or "saw" from a largetooth sawfish with several teeth missing (black marks on ruler are apart) As suggested by the alternative name common sawfish, it was once plentiful, but has now declined drastically leading to it being considered a critically endangered species by the IUCN. Because of the "saw" they are particularly prone to becoming entangled in fishing nets. In the Niger Delta region of southern Nigeria, sawfish (known as oki in Ijaw and neighbouring languages) are traditionally hunted for their saws, which are used in masquerades. The largetooth sawfish has been extirpated from many regions where formerly present. Whether it survives anywhere in Southeast Asia is generally unclear, and is now threatened by the planned Nicaragua Canal. In West Africa, the Bissagos Archipelago has often been considered the last remaining stronghold, Following taxonomic changes, the ESA listing was updated to P. pristis in December 2014. Sawfish are protected in Australia and the United States where a number of conservation projects have been initiated, ==See also==