There are 10 different species of the sawshark: African Dwarf, Bahamas/American, Dwarf, Eastern, Japanese, Common/Longnose, Phillipine, Shortnose, Sixgill, and Tropical Sawsharks. Some people confuse sawsharks with sawfishes, but those are actually rays. While less is known about these species of sawsharks than many of its shark relatives, we think you should get to know some facts about these interesting creatures.
The Bahamas, or American, sawshark is slender, with an extremely long, narrow saw-like snout with a pair of barbels halfway between the mouth and rostral tip. They have two dorsal fins and five gill slits on the sides of the body. With light grey on their upper side, and a whitish color on the lower side, its pectoral fins have lighter edges and the dorsal fins of the young have a darker edge.
Sawsharks can grow to 2.7 feet (81 centimeters) or more in length. Maximum size for a bahamas sawshark is three feet. The snout makes up 31 to 32% of its total length!
The Bahamas sawshark can only be found on or near the bottom of continental and insular slopes of the northwest and southeast Atlantic, west Indian and west Pacific Ocean. They will be in shallow water in temperate regions, deeper in the tropics. Typically these waters will be between 1437 to 3123.4 feet (438 to 952 meters) deep.
This shark has 23 large, lateral sawteeth, 13 in front of and 10 behind the barbels. Juvenile sawsharks typically have one smaller tooth between its large lateral teeth.
The Common Sawshark
Like all sawsharks, the common, or longnose sawshark, also has saw-like snout with a pair of barbels. It is a slender shark with a slightly depressed and flattened body.
It is much more patterned than the Bahamas shark, with darker bands and brownish spots and blotches on a pale yellowish brown background.
Common sawsharks are common to southern Australia, from southern New South Wales, to mid-Western Australia. You can find them in deeper, warm waters, on continental shelves and slopes. They may be lying on the sea floor, usually on sand or mixed gravel-sand substrates.
Males can reach a maximum length of 4.4 (1.3 meters), but the females can get up to 5 feet (1.52 meters).
These sharks have a long, tapering rostrum with teeth on both sides. Their teeth vary in size, with smaller teeth in between the larger teeth. The rostrum has 19 to 21 enlarged teeth on each side.
The common sawshark lives for more than 15 years. The females will breed approximately every one to two years. It is believed all sawsharks are ovoviviparous, and the common sawshark will give birth to 3-22 young. 10 pups are the average. Gestation period, or the length of pregnancy, is about 12 months and the pups are born in shallow coastal areas. The pups are about 11-14 (or about 28-35 centimeters) inches long at birth. The rostal teeth are pliable and bent rearward at birth to prevent damage to the delivering female.
Similar in appearance to the other species of sawshark, the Japanese sawshark has a flat snout, studded with teeth. Two long, sensitive, whisker-like barbels protrude from the middle of their snout. They use the barbels, as well as electro-receptors located on the underside of its saw, to help locate prey buried in the sand. It will skim across the ocean floor looking for it’s next meal, which often consists of fish, squid, shrimp and other crustaceans. The Japanese sawfish uses its snout to uncover the meal from the sand and then kill or render it unable to get away with rapid whips from its snout.
The Japanese sawshark grows to no larger than 6 feet or about 1.5 meters.
Like other sawsharks, it is ovoviviparous, and mothers will typically birth 10 pups in each litter over the course of their 15 years of life.
This shark is unique to other species of sawshark in that it has six gills instead five, and it has some unfortunate qualities and circumstances that are threatening its population.
The sixgill sawshark is the only species of sawshark that is on the IUNC list as something other than ‘least concern’ or ‘data deficient’ (meaning there is not enough research on the population to determine its threat of endangerment). The sixgill sawshark is considered ‘near threatened.’ While this may not sound as dire as the species of shark that are ‘vulnerable’, ‘endangered’, or ‘critically endangered’, this should warrant concern, as well as action against its threats.
Data is lacking on the threats and population trends of this sawshark; however, it is believed that its restricted distribution, the levels of bycatch of this specie, and its reproductive challenges all account for its decline.
Sixgill sawsharks can be found on the continental shelves and upper slopes off the coasts of southern Africa and Madagascar. They tend to stay where the waters are warmer and subtropical, avoiding the cold-temperate west coast of South Africa, north of Cape Town. There are few accounts of this shark venturing elsewhere, creating a specific geographic distribution, where people fishing for other catch are present.
When a sixgill sawshark is caught, it often discarded as bycatch (unwanted product of fishing) and could be injured or killed in the process. We do not know how often these sawsharks are caught and released because it is not properly monitored, but it is thought to be at an unsustainable rate due to the shark’s vulnerability to net gear.
These sharks are considered to be a relatively unproductive species. Their litters are smaller than other sawsharks, typically 5-7 pups instead of the usual 10, and despite having upwards of 17 developing eggs in utero.
African Dwarf Sawshark
Exciting news in the world of sawsharks! The African dwarf sawshark was just recently discovered in 2011. One was caught in deep water off the coast of Mozambique. How cool!
While it was found near Mozambique, there have been accounts of this species off the coasts of Somalia and Kenya. However, these reports remain unconfirmed. They live on the continental shelf, at depths reaching 286 to 500 meters (938 to 1,640 feet).
We don’t yet know much about the biology of the African dwarf sawshark. It would appear, based on the stomach contents taken by researchers in the field, that these sharks prefer small crustaceans. Nothing is known about the reproductive habits of this sawshark, though it is safe to assume that it is ovoviviparous.
Sawsharks are incredible creatures with a unique appearance. All of the species of sawshark have many qualities in common, but they all have their place in this vast, beautiful world.