Largetooth sawfish

The largetooth sawfish (Pristis pristis, syn. P. microdon and P. perotteti) is a species of sawfish, family Pristidae. It is found worldwide in tropical and subtropical coastal regions, but also enters freshwater. It has declined drastically and is considered critically endangered. A range of English names have been used for the species, or populations now part of the species, including common sawfish (despite it being far from common today), wide sawfish, freshwater sawfish, river sawfish (less frequently, other sawfish species also occur in freshwater and rivers), Leichhardt's sawfish (after explorer and naturalist Ludwig Leichhardt) and northern sawfish. The taxonomy of Pristis pristis in relations to P. microdon (claimed range: Indo-West Pacific) and P. perotteti (claimed range: Atlantic and East Pacific) has historically caused considerable confusion, but 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 an analysis of NADH-2 genes there are three main clades of P. pristis: Atlantic, Indo-West Pacific and East Pacific. Its scientific name Pristis (both the genus and specific name) is derived from the Greek word for saw. The largetooth sawfish possibly reaches up to 7.5 m (25 ft) in total length, but the largest confirmed was a West African individual that was 7 m (23 ft) long. An individual caught in 1951 at Galveston, Texas, which was documented on film but not measured, has been estimated to be of similar size. Today most individuals are far smaller and a typical length is 2–2.5 m (6.6–8.2 ft). Large individuals may weigh as much as 500–600 kg (1,102–1,323 lb), or possibly even more. 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. On average, females have shorter rostrums with fewer teeth than males. The proportional rostrum length also varies with age, with average being around 27% of the total length of the fish, but can be as high as 30% in juveniles and as low as 20–22% in adults. Its upperparts are generally grey to yellowish-brown, often with a clear yellow tinge to the fins. Individuals in freshwater may have a reddish colour caused by blood suffusion below the skin. The underside is greyish or white.