A saw shark is a member of the Pristiophoriformes order of sharks, which contains seven species that are known for elongated snouts edged with sharp teeth of alternating length. The saw shark has two long barbels connected to its snout that it uses for hunting and subduing the small fish, squid and crustaceans that it eats. A saw shark's appearance is dominated by the length of its rostral snout, often reaching 30 percent of the shark's body in size. The shark reaches average lengths of 3 feet (1 m), and are located in the oceans surrounding Japan, Australia, South Africa and the Caribbean.
Saw sharks are often confused with saw fish because they have a similar appearance. The two creatures differ in that a saw shark has gills on the side of the head, making it a true shark, and a saw fish has gills located on its underneath. Additionally, a saw fish does not have long barbels like a saw shark, and its teeth are all the same size instead of alternating in length like a saw shark's teeth.
Within the Pristiophoriformes order, there are seven types of saw sharks. The first species, Pliotrema, has six gill slits, and the other six species have only five gill slits. Pliotrema also differs from the other species of saw sharks in that its teeth have basal ledge ridges and posterior serration. This species of saw shark lives exclusively in the Indian Ocean.
There is no known danger to humans from saw shark attacks, and the sharks are believed to be numerous, with no danger of extinction. When caught by fisherman, the underbelly of the shark is cooked and eaten as a delicacy, especially in Australia. The rostral nose of the shark is often removed by fisherman and sold separately as an ornament. The saw shark usually is caught unintentionally in the nets intended for other types of fish.
When hunting, saw sharks swim along the bottom of the ocean, through the mud and sediment. It uses its barbels to locate small fish, crustaceans and squids that are hiding. The barbels contain chemical receptors and use pressure sensors to seek out prey. Once prey is located, the shark tosses its head violently side to side, impaling its prey using its serrated teeth and rostral snout.
The life expectancy of a saw shark is 10 to 15 years. The sharks are ovoviviparous, meaning they give birth to live young that develop as eggs inside of the uterus. As many as 22 babies can be born at one time, and they usually are born during the winter months.