(Pristiophoriformes)
Saw Sharks
Пилконосі акули
A sawshark or saw shark is a member of a shark order (Pristiophoriformes) bearing a unique long, saw-like rostrum (snout or bill) edged with sharp teeth, which they use to slash and disable their prey.
Sawsharks are found in many areas around the world, most commonly in waters from the Indian Ocean to the southern Pacific Ocean. They are normally found at depths around 40–100 m, but can be found much lower in tropical regions. The Bahamas sawshark was discovered in deeper waters (640 m to 915 m) of the north-western Caribbean.
Sawsharks have a pair of long barbels about halfway along the snout. They have two dorsal fins, but lack anal fins. Genus Pliotrema has six gill slits, and Pristiophorus the more usual five. The teeth of the saw typically alternate between large and small. Saw sharks reach a length of up to 5 feet and a weight of 18.7 pounds, with females tending to be slightly larger than males.
The body of a longnose saw shark is covered in tiny placoid scales: modified teeth covered in hard enamel. The body is a yellow-brown color which is sometimes covered in dark spots or blotches. This coloration allows the saw shark to easily blend with the sandy ocean floor.
These sharks typically feed on small fish, squid, and crustaceans, depending on species. The function of the sawshark barbels are not well understood, and neither is how they use their rostrum. It is possible they use it in a similar fashion as sawfishes, and hit prey with side-to-side swipes of the saw, crippling them. The saw could also be utilized against other predators in defense. The saw is covered with specialized sensory organs (ampullae of Lorenzini) which detect an electric field which is given off by buried prey.
Saw sharks life history is still poorly understood. Mating season occurs seasonally in coastal areas. Saw sharks are ovoviviparous meaning eggs hatch inside the mother. They have litters of 3–22 pups every 2 years. After 12 months of pregnancy, the pups are born at 30 cm long. While in the mother, pups’ rostral teeth are angled backwards to avoid harming the mother. The life expectancy of sawsharks is still poorly understood, but they are thought to live to 10 years or more.
(Pristiophorus cirratus)
Common Sawshark
Пилконоса акула довгоноса
It is found in the eastern Indian Ocean around southern Australia and Tasmania on the continental shelf at depths of 20–600 m. While it may venture into bays and estuaries on occasion, it prefers sandy and gravelly areas offshore between 37–146 cm.
(Pristiophorus japonicus)
Japanese Sawshark
Пилконоса акула японська
It is found in the north-western Pacific Ocean around Japan, Korea, Taiwan, and northern China between latitudes 48°N and 22°N. It inhabits sandy or muddy bottoms on the continental shelf at depths of 50–800 m.
(Pristiophorus nudipinnis)
Southern Sawshark
Пилконоса акула коротконоса
It is found from the Great Australian Bight, to off the coast of Tasmania and Melbourne (Australia), at a depth of 37–165 m.
(Pristiophorus schroederi)
Bahamas Sawshark
Пилконоса акула багамська
It is found in the western Central Atlantic Ocean from the Bahamas and Cuba at depths of 400–1,000 m.
(Pristiophorus delicatus)
Tropical Sawshark
Пилконоса акула тропічна
It is endemic to north-eastern Australia, found on the upper continental slope off Queensland from south of the Samaurez Reef, at a depth of 246–405 m.
(Pristiophorus nancyae)
African Dwarf Sawshark
Африканська карликова пилконоса акула
It is found off the coast of Mozambique. Possible records of this species off the coasts of Somalia and Kenya remain unconfirmed. It lives a benthic lifestyle on the continental shelf, at depths of 286–500 m.
(Pristiophorus lanae)
Lana's Sawshark
Пилконоса акула філіппінська
It is found in the Philippines off Apo Island and southern Luzon at depths of 230–590 m.
(Pliotrema warreni)
Sixgill Sawshark
Шестизяброва пилконоса акула
It is found in the temperate and subtropical waters of the western Indian Ocean between latitudes 23° S and 37° S, at depths of 37–500 m.
(Pliotrema annae)
Anna’s Sixgill Sawshark
Шестизяброва пилконоса акула Анни
It is found off Zanzibar in the western Indian Ocean, where it inhabits shallow waters at depths of 20–35 m.
(Pliotrema kajae)
Kaja’s Sixgill Sawshark
Шестизяброва пилконоса акула Каї
It is found in Madagascar and the Mascarene Plateau. in the western Indian Ocean, where it lives in submarine ridges and upper insular slopes at depths of 214–320 m.
