Japanese Sawshark

• Maximum lengthAbout 1.5 m (5 ft), females larger
• WeightNot reliably recorded; a 1.2 m adult is roughly 5–6 kg (11–13 lb)
• LifespanUnknown; no ageing study for this species
• Depth range50–800 m (165–2,600 ft), mostly 100–500 m
• DietSmall bottom fish, squid, shrimps and other crustaceans
• IUCN statusLeast Concern (assessed 2020)

How to recognise a Japanese sawshark

Nothing else on the Japanese shelf looks like this. The snout is drawn out into a flat blade, a fifth or more of the whole animal, edged on both sides with rostral teeth that alternate in size: a long needle-like tooth, then one or two short ones, then another long one. Roughly twenty of the large teeth sit on each side in front of the barbels and about ten behind them, and unlike the fixed teeth of a sawfish they are rooted in skin rather than in the blade itself and are replaced as they are lost. From the underside of the saw, a little nearer the mouth than the tip, hang two long barbels, the moustache that gives the family its odd, comic face.

Behind the saw the body is cylindrical and tapers evenly to a tail with a long upper lobe and almost no lower lobe. Both dorsal fins are broad, triangular and without spines, the pectoral fins are large and wing-like, and there is no anal fin, which is the quickest way to know you are looking at a sawshark and not at a dogfish. The five gill slits sit on the sides of the head in front of the pectoral fins; the sixgill sawshark of the western Indian Ocean has six. The colour is a plain reddish or yellowish brown above and cream below, without the dark spots and saddles that mark the Australian longnose sawshark, and the saw sometimes carries a faint darker stripe down its midline.

How big does a Japanese sawshark get?

The Japanese sawshark is a modest animal. The largest measured specimens are females of around 1.5 m (5 ft) total length, close to a third of which is the saw, and the biggest males are shorter, at about 1.3 m (4.3 ft). The commercial catch off Honshu is mostly sharks of 0.8 to 1.2 m, and a 1 m sawshark is already an adult: males mature at around 1 m and females a little larger. Weight is rarely written down; a slender 1.2 m shark whose saw weighs almost nothing is probably 5 to 6 kg (11 to 13 lb), a fraction of a stocky dogfish of the same length.

Newborns are about 30 cm (12 in) long, and the saw is already fully formed at birth, though the rostral teeth lie folded back against the blade under a membrane so that the pup does not lacerate its mother or its litter-mates on the way out. They stand upright within a day or so. The old version of this page counted "25 to 45 teeth on either side"; that figure includes the small teeth between the large ones and overstates the working blade. The size bar below sets the 1.5 m maximum against a diver.

Where Japanese sawsharks live

The species belongs to the temperate north-west Pacific. Its heartland is Japan, from the Pacific and Sea of Japan coasts of Honshu south through Shikoku and Kyushu, and it continues around the Korean Peninsula (South Korea) into the Yellow Sea, the Bohai Sea and the East China Sea off northern China and Taiwan. Records fade out south of Taiwan; it is a cool-water shark and does not enter the tropical South China Sea.

It lives on the bottom, on sand and mud where the saw and barbels earn their keep, at depths of about 50 to 800 m (165 to 2,600 ft). Most of the fishery catch comes from the outer continental shelf and the top of the slope, between roughly 100 and 500 m. No temperature preference has been measured for the species, but Japanese trawl records suggest a seasonal shuffle up and down the slope that follows the bottom water: shallower in the cool months, deeper when the shelf warms in summer. Young sharks seem to use shallower ground on the inner shelf than adults, but no nursery has been mapped. The map below shows the known distribution, and the list beneath it the SharkSider country pages that cover it.

What Japanese sawsharks eat and how the saw is used

A sawshark eats what lives in or just above the sediment: small bottom fish such as gobies, dragonets and juvenile flatfish, squid and cuttlefish, and shrimps and other crustaceans. Stomachs from the Japanese catch are dominated by small fish and crustaceans, with cephalopods a smaller share, though no long-term diet study has been published for this species and much of what is written about it is borrowed from the Australian longnose sawshark, whose habits are better known.

The hunt starts with the barbels. Trailing along the bottom as the shark cruises just above it, they carry taste and touch receptors that register buried animals. The underside of the saw is peppered with ampullae of Lorenzini, so once a barbel finds something the shark can pin down the faint electrical field of a hidden shrimp's heartbeat. The saw then works in two ways: a sideways sweep through the sediment uncovers the prey, and a quick lateral slash stuns or impales it before it is picked up in the small, protrusible mouth. Captive longnose sawsharks have been watched slashing at pieces of fish with the saw before eating them, an action that seems to come as naturally to them as biting does to other sharks, and there is no reason to think the Japanese species behaves differently. The teeth in the mouth itself are small and cusped and are used to hold, not to cut.

Behaviour and senses

Almost everything known about the living animal comes from trawl decks and a few aquarium tanks, because nobody dives to 200 m on a mud plain to watch one. What the trawls show is a shark that spends the day resting or cruising slowly on the bottom and feeds mainly at night, when the animals it eats come out of the sediment. Sawsharks often arrive in a net in numbers, and loose mixed-sex schools are suspected, though whether that reflects social behaviour or simply a good patch of feeding ground is not known.

The sensory kit is built for the bottom. The eyes are large and set high on the head so the shark can see above itself while its snout is in the mud; the spiracles behind them draw clean water to the gills when the mouth is pressed to the sediment (see what spiracles do). Add the barbels and the electroreceptors on the saw, and a lateral line that runs the length of the body and out along the rostrum, and the shark has a detailed picture of the bottom without needing to see any of it.

The saw is also a defensive weapon. A hooked or netted sawshark thrashes its head from side to side, and Japanese fishermen handle them with gloves and a grip behind the blade. Larger sharks and big bony fish are presumed predators, but a documented case of anything eating a Japanese sawshark is hard to find. Like all sharks it wears a coat of dermal denticles, tooth-like scales that lower drag and shield the skin, which is why the family name means "saw-bearer" but the skin feels like sandpaper (see shark anatomy).

Reproduction and lifespan

Japanese sawsharks are ovoviviparous, or more precisely yolk-sac viviparous: the eggs hatch inside the mother and the embryos grow on their yolk alone, with no placenta and no egg-eating, until they are born as fully formed 30 cm miniatures. Litters are typically about 12 pups, and the young turn up in the Japanese catch in spring and early summer, which points to a spring birth season, although the gestation period has never been measured. As in other sawsharks the rostral teeth of the embryo lie flat and sheathed until after birth.

Both sexes mature at roughly 1 m total length. Age at maturity and maximum age are unknown; growth bands in the vertebrae have not been read for this species, and the only guide is the Australian longnose sawshark, which is thought to live around 15 years. Until someone ages a series of Japanese specimens, treat any lifespan figure you read for this species as a guess. Our page on how long sharks live explains why small, early-maturing sharks like this sit at the short end of the range, and the ovoviviparous sharks page explains the breeding mode in more detail.

Is the Japanese sawshark dangerous to people?

No. The Japanese sawshark has never hurt anyone in the water, and the SharkSider database, which reaches back to the sixteenth century, holds no incident attributed to it. The reasons are physical. It lives on the bottom below 50 m, far beneath any swimmer or surfer; its mouth is small and set well back under the saw, with teeth made for gripping shrimps; and its instinct when disturbed is to bolt across the sand, not to investigate.

The only people who get close to one are fishermen, and the only injuries the species causes are cuts from the rostral teeth when a live shark is unhooked or sorted from a net. Handle one behind the saw, or better, not at all. None of the advice on our surviving a shark attack page applies here, and the sawshark is simply absent from the shark attacks in Japan record, which is dominated by white and tiger sharks.

The SharkSider database has no incident attributed to this species. The database draws on the International Shark Attack File, the Global Shark Attack File and verified local reports, and is updated weekly.

Conservation status

The IUCN Red List assessed the Japanese sawshark in 2020 as Least Concern, a step up from the Data Deficient listing it carried for a decade, on the grounds that catches in Japanese bottom-trawl and set-net fisheries appear stable and the species remains common in survey hauls. It is not listed under CITES or the Convention on Migratory Species and has no specific national protection in Japan, Korea or China.

Untouched it is not. The species is taken throughout its range by bottom trawls, gillnets and set nets, mostly as bycatch in fisheries for flatfish, shrimp and other groundfish. In Japan it has real value: the flesh is good and is a traditional ingredient in kamaboko and other fish-paste products, so landings are kept rather than discarded. They are not reported separately from other sharks, which makes trend analysis hard. In the Yellow Sea and East China Sea, among the most intensively trawled waters on earth, its status is simply unknown, and it is reasonable to assume the Chinese and Korean populations have thinned along with the rest of the bottom fauna.

Its biology is on its side. A litter of a dozen pups and maturity at a metre make it far more resilient than a deep-water dogfish or a large pelagic shark, and it has none of the fin value that drives the trade described on our why sharks are endangered page.

Similar species and close relatives

The sawshark family contains only about ten species, all in the genus Pristiophorus apart from the six-gilled Pliotrema. In the north-west Pacific the Japanese sawshark stands alone; its nearest neighbours are the tropical sawshark of north-east Australia and the two well-known Australian species, the spotted longnose sawshark and the stubby shortnose sawshark. The Bahamas sawshark and the African dwarf sawshark show how far the family spreads, and the sixgill sawshark is the odd one out with its extra gill slit.

The animal most often confused with any sawshark is not a shark at all. Sawfishes are rays, with the gill openings on the underside of the head, no barbels, and rostral teeth of even size set into sockets in the blade, and they grow many times larger. In Japanese waters the sawshark also shares the bottom with the Japanese angelshark, another flat, sand-coloured ambusher, and with the small cloudy catshark, but neither has a saw, and once you have seen the moustache there is no mistaking it.

• Longnose Sawsharkspecies profile
• Shortnose Sawsharkspecies profile
• Tropical Sawsharkspecies profile
• Bahamas Sawsharkspecies profile
• Sixgill Sawsharkspecies profile
• African Dwarf Sawsharkspecies profile

Written and reviewed by

SharkSider Editorial Team

A small team focused on researching sharks and making marine biology easy to understand. Every page is reviewed against current species records and the SharkSider attack database, and updated when new incidents or research appear.

Published December 1, 2014 · Last updated September 22, 2026 · No incident attributed to this species in the SharkSider attack database, which is updated weekly.