Prickly Shark

• Maximum length4 m (13 ft); females mature at 2.5–3 m
• Weight266 kg (586 lb) for a 3 m female, the heaviest weighed
• LifespanNever measured; no validated age study exists
• Depth range11–1,100 m (36–3,600 ft), usually below 200 m
• DietBony fish, small sharks, chimaeras, octopus, squid
• IUCN statusData Deficient (assessed 2017)

How to recognise a prickly shark

Run a hand along the flank and you have the identification, although you should not: the skin is covered in scattered, non-overlapping denticles shaped like rose thorns, each rising to a point from a star-shaped base, and they are sharp enough to graze skin. No other shark in the eastern Pacific feels like this.

The silhouette is just as odd. The body is thick, soft and cylindrical, tapering to a stout tail stalk, with a short flattened head, widely separated nostrils under small skin flaps, and small eyes without a nictitating membrane. There is no anal fin at all, and the two small, spineless dorsal fins sit so far back that both stand behind the origin of the pelvic fins, almost over the tail. The fifth gill slit is the longest, another anatomical quirk worth checking.

Colour is plain brown to grey, sometimes with a purplish sheen, paler underneath and around the mouth, with a dark trailing edge to the fins. The jaws are wide and carry roughly 21 to 25 tooth rows above and 20 to 27 below; each tooth is a low blade with a strong angled main cusp flanked by up to three small cusplets on either side, built for gripping and shearing soft prey. The one shark it can genuinely be mistaken for is its Atlantic and Indian Ocean cousin, the bramble shark, whose denticles are far larger, fewer, and often fused into plates.

How big do prickly sharks get?

The largest reliably reported prickly shark measured about 4 m (13 ft 1 in) in total length, which makes it the biggest member of its small family and a genuinely large shark by any measure. Most animals encountered are considerably shorter. Males mature at roughly 2 m and females between 2.5 and 3 m, so an adult of either sex is usually somewhere between 1.8 and 3 m rather than near the maximum.

Weight is recorded even more rarely than length, because prickly sharks come up in trawls and gill nets that nobody sets for them. The heaviest individual on record is a female of about 3 m that weighed 266 kg (586 lb). That is a great deal of mass for the length, and it reflects the build: this is a soft, barrel-shaped animal with a huge oil-filled liver rather than a streamlined swimmer.

Newborns arrive at 40 to 45 cm, small relative to the adult size, which is what you would expect of a species that produces enormous litters rather than a handful of well-grown pups. Juveniles look flabbier and less bulky than adults and are rarely seen at all; most of the shallow-water sightings in Monterey Canyon involve sub-adults and adults. Underneath, the scale bar measures that 4 m maximum against a 1.8 m diver.

Where prickly sharks live

The prickly shark is a Pacific animal, recorded in scattered patches right around the rim. In the west it is known from Japan, Taiwan, Palau, New Caledonia, Tonga, eastern and southern Australia and New Zealand. In the east it turns up off Hawaii, from Oregon and California south through the Gulf of California in Mexico, around the Cocos and Galápagos islands, and from Costa Rica down to Peru and Chile.

Habitat is more consistent than the map suggests. This is a shark of continental and island slopes, submarine canyons and seamount flanks, where it cruises just above muddy or sandy bottoms. Records span 11 to about 1,100 m, with a few reports from deeper still, but the species is normally an animal of a few hundred metres down, in cold water of roughly 5.5 to 11 °C.

Two places break that rule and have made the species watchable. Monterey Canyon off central California brings deep water within reach of the coast, and prickly sharks there are seen year-round in as little as 15 to 35 m, occasionally in groups of thirty or more. In 2024 researchers documented a comparable aggregation over seamounts off Pacific Panama. Both sites suggest the species gathers far more often than the scattered museum records imply.

What prickly sharks eat and how they hunt

For a shark that looks sluggish, the prickly shark eats surprisingly capable prey. Stomach contents include hakes, rockfishes, herring, mackerel and flounders among the bony fish; spiny dogfish, young bluntnose sixgill sharks and small deep-water catsharks among the cartilaginous ones; chimaeras, which few predators tackle because of their venomous dorsal spine; and a steady supply of octopus and squid.

The mechanism is suction. The mouth is relatively small but the pharynx behind it is cavernous, and the hyoid apparatus is built to drop fast, creating a pressure drop that pulls water and prey in together. A shark that cannot outswim a rockfish can still take one from a standing start if it gets close enough, and in the dark of a canyon wall at 400 m getting close is the easy part.

Once the prey is inside, the low blade-like teeth with their cusplets hold and shear. Feeding is concentrated around dusk and through the night, matching the upward movement of the fish shoals the shark follows. Video from Monterey shows animals hanging almost motionless over the bottom by day, then rising through the water column as the light goes. The ampullae of Lorenzini on that broad flat snout are the sense that matters most at these depths, where vision is nearly useless.

Behaviour, senses and adaptations

Prickly sharks follow a daily vertical rhythm. Acoustic tracking in Monterey Canyon showed the sharks resting by day in deep, cold water in a few favoured spots, then moving up the canyon walls and into shallower water at dusk, returning before dawn. They are most active in the hours either side of darkness and spend the rest of the time barely moving, a low-energy strategy common to deep slope sharks.

The aggregations are the most interesting part. Most deep-water sharks are solitary, but prickly sharks in Monterey have repeatedly been found in loose groups of more than thirty animals in the same small area, apparently using it as a daytime refuge rather than a feeding ground. Nobody knows what holds the group together; there is no evidence of cooperative hunting, and size and sex sorting has not been demonstrated.

Physiologically, the species is built for oxygen-poor depth. It tolerates the low-oxygen layers of the eastern Pacific that exclude most large predators, which effectively hands it an ocean basin of its own to hunt in. A very large, low-density liver provides buoyancy without effort, the small eyes are backed by a reflective tapetum, and the thorny dermal denticles almost certainly serve as armour against the larger sharks that share the slope. All of that adds up to an animal that spends very little energy for its size.

Reproduction and lifespan

The prickly shark is ovoviviparous, or in the modern phrasing an aplacental yolk-sac live-bearer. Eggs hatch inside the mother's uterus and the embryos live on their own yolk until birth; there is no placenta and no supply of extra eggs for the pups to eat, so the mother's contribution is made before pregnancy rather than during it. Sources that call the species simply viviparous are using the older, looser sense of the word.

Fecundity is the striking part. A single examined female carried 114 embryos, the largest litter ever recorded in the family and one of the biggest in any shark. Because that is a sample of one, nothing is known about the normal litter size, and it would be wrong to treat 114 as typical. Pups are born at 40 to 45 cm.

Everything else about the reproductive cycle is unrecorded: there is no established mating season, no gestation period, no birth site and no nursery area for this species. Age and growth are equally blank. No validated ageing study has been published, so the lifespan is genuinely unknown, and any figure you see quoted has been borrowed from another deep-water shark. Judging by relatives of similar size and depth, slow growth and a long life are likely, which is exactly what makes a fishery hard to manage (see how long sharks live).

Are prickly sharks dangerous to people?

No. The SharkSider database holds no incident attributed to this species, and neither does any other record. Divers in Monterey Canyon and in Palau have approached prickly sharks repeatedly at close range: the usual response is that the animal tolerates the intrusion for a while and then eases away into deeper water. It is slow, it has no interest in anything the size of a person, and the vast majority of its life is spent hundreds of metres below any swimmer.

The only genuine hazard is the skin. Those thorn-like denticles will open a shallow cut on an unprotected hand, and fishermen who haul a prickly shark aboard learn quickly to handle it with gloves and a tail rope. Even that is a hazard of the catch, not of the shark's behaviour. On the very short list of large sharks that no one needs to worry about, this one sits near the top alongside the other deep slope species on our page of the least dangerous 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 assessed the prickly shark in 2017 and placed it in the Data Deficient category, which means exactly what it says: there is not enough information to judge whether the population is stable or falling. Records come in ones and twos across an enormous range, there is no time series of abundance anywhere except Monterey, and the species is easily confused with the bramble shark in catch statistics, so even the raw numbers are unreliable.

Direct fishing pressure is light. The flesh is soft and of little commercial value, so no fleet targets the species, and most captures are bycatch in bottom trawls, deep gill nets and longlines set for other fish. An Australian fisheries assessment rated the risk to the local stock as negligible on that basis. Set against that is a life history that looks fragile: large size, late maturity, deep cold water and, in all likelihood, slow growth.

Two things would change the picture. The first is species-level reporting from deep-water fisheries around the Pacific rim, so that Echinorhinus catches stop disappearing into a general shark category. The second is a validated age and growth study, without which no catch limit can be set with any confidence. Until then this shark stays in the large grey zone of deep-sea species that are neither known to be threatened nor known to be safe, a theme that runs through our page on why sharks are endangered.

Similar species and close relatives

The family Echinorhinidae contains only two living species, and the other one is the bramble shark of the Atlantic, Mediterranean and Indian Ocean. The two are alike in shape, size and habits, and the reliable difference is the skin: bramble shark denticles are large, sparse and sometimes fused into plates up to 1.5 cm across, while the prickly shark's are smaller, far more numerous and never fused. Their ranges barely overlap, so an Echinorhinus in the Pacific is almost always this species.

Beyond the family, the closest relatives are the dogfish sharks of the order Squaliformes, and the prickly shark shares with them the absent anal fin and the spineless or spined twin dorsals set far back. The Portuguese dogfish, the kitefin shark and the giant Pacific sleeper shark occupy the same slope depths in the same ocean. Do not confuse this species with the prickly dogfish, a small, humpbacked rough shark of Australian and New Zealand waters that shares part of the name and none of the ancestry. On the canyon bottom the animal most often mistaken for a prickly shark is a young bluntnose sixgill, which has six gill slits and a single dorsal fin.

• Bramble Sharkspecies profile
• Bluntnose Sixgill Shark (Hexanchus griseus)species profile
• Pacific Sleeper Sharkspecies profile
• Portuguese Dogfishspecies profile
• Kitefin Sharkspecies profile
• Prickly Dogfish Sharkspecies 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 August 23, 2022 · Last updated September 22, 2026 · No incident attributed to this species in the SharkSider attack database, which is updated weekly.