Pale Catshark

• Maximum length21 cm (8 in) juvenile, the only specimen; adult size unknown
• WeightNever recorded; a few tens of grams
• LifespanUnknown
• Depth range655 m (2,150 ft), single record
• DietUnknown; probably small crustaceans, squid and fish
• IUCN statusLeast Concern (assessed 2019)

How to recognise a pale catshark

Only one person has ever needed to identify a pale catshark, and he had the advantage of holding it: Max Weber, leader of the Siboga expedition, who described the specimen in 1913. What he had was a soft, slender catshark with the head shape that defines Apristurus: a broad, flattened, spade-like snout, small eyes set well back, wide nostrils, and a mouth that reaches far round the head with long grooves, the labial furrows, running back from both jaws. The gill slits are short, the longest about the length of the eye.

The fins follow the genus pattern too. The first dorsal fin is noticeably smaller than the second and begins over or behind the rear of the pelvic fin base, the pectorals are broad, the pelvics small and low, and the anal fin is long and angular, separated from the low, narrow tail by a small notch. The tail itself is a long, ribbon-like blade with no strong lower lobe. The teeth are tiny and multi-cusped in both jaws, the usual equipment of a shark that eats small, soft prey.

What sets the species apart from its many relatives is colour. Most Apristurus are dark chocolate, black or grey; this one was pale, white to reddish-white, which is where both the common name and the paleness of its preserved skin come from. The lack of dark fin edges and the very short gill openings help separate it from the longnose and brown catsharks, but since no second specimen has been examined, any key is provisional.

How big is a pale catshark?

The honest answer is that no one knows. The holotype measured about 21 cm (8.3 in) in total length and was immature, so the adult is larger, but how much larger is a guess. Other members of the genus give a sense of the range: the smallest Apristurus mature at 35 to 40 cm and the largest, such as the longfin catshark, approach 90 cm. A pale catshark of 40 to 60 cm as an adult would be unsurprising; a metre-long one would not.

Weight has never been recorded. A 21 cm catshark weighs a few tens of grams, less than a smartphone, and even a fully grown one would be a fish you could hold in one hand. Nothing can be said about sexual dimorphism, birth size or growth rate; the single animal was a juvenile of unrecorded sex whose vertebrae were never sectioned. The size bar below therefore shows the only measurement that exists, the holotype, against a 1.8 m diver, and should be read as a minimum, not a maximum. If a second specimen is ever trawled from the Makassar Strait, this section will be the first to change.

Where the pale catshark lives

The species has a single dot on the map: the slope of the Makassar Strait, the deep channel that separates Borneo from Sulawesi in central Indonesia, where the Siboga's dredge brought it up from 655 m (2,150 ft) of water. The strait is a major throughflow between the Pacific and Indian Oceans, with steep walls that drop to more than 2,000 m and a floor of soft mud, the kind of habitat in which most Apristurus species spend their lives lying on or hovering just above the bottom.

Whether the pale catshark ranges more widely is unknown, but probably. Deep-water catsharks are rarely confined to one strait; several Indonesian and Philippine slope species turned out, once deep surveys reached them, to occur along hundreds of kilometres of slope. The Sulawesi Sea, the Flores Sea and the slopes off eastern Borneo and the Philippines are the obvious places to look. The water at 655 m in this region is a stable 5 to 7 °C, dark and oxygen-poor, and any population will be tied to that depth band rather than to the shallow reefs a few kilometres away. No country or state page on this site lists the species, because nobody has seen one since 1899.

What the pale catshark eats

The holotype's stomach was not analysed, or if it was, the result was never published, so the diet is inferred entirely from relatives. Stomach studies of other Apristurus, from the brown catshark of the eastern Pacific to the Japanese and Icelandic species, agree closely: small shrimps and other crustaceans first, then small squid, then small midwater and bottom fish such as lanternfish and bristlemouths, with occasional polychaete worms. A shark with a flattened snout, a wide mouth and dozens of tiny multi-cusped teeth is equipped for exactly that menu, sucking up and gripping soft prey rather than biting pieces from anything.

The hunting method can be reconstructed the same way. Catsharks of the deep slope are slow, energy-saving animals that cruise a few centimetres above the mud, sweeping the broad snout over the bottom and relying on smell, the lateral line and the electrical sense of the ampullae of Lorenzini to find buried shrimps in the dark. The tiny eyes of the pale catshark, small even for the genus, suggest vision matters less here than in the big-eyed lanternsharks that share the depth. Feeding is probably continuous and opportunistic rather than tied to any daily rhythm.

Behaviour and adaptations to the deep slope

Nobody has watched a pale catshark alive, so its behaviour is a matter of reading the body. The soft, flabby musculature and thin skin typical of Apristurus mark it as a low-energy animal: a shark that does not chase, migrate or fight, but drifts and creeps in cold water where meals are small and far apart. The large oily liver that gives deep-water catsharks near-neutral buoyancy lets it hang above the bottom with minimal effort, and the long, low tail is built for slow sculling rather than bursts of speed.

The senses are tuned accordingly. Large nostrils and long labial furrows point to smell and taste as the leading senses, with the electrical sense doing the close work; the eyes, though small, have a reflective layer that makes the most of the faint bioluminescence around them. Pale colour is unusual at 655 m, where most fish are black or dark brown, and its function is unclear; some deep-sea catsharks are whitish simply because pigment is metabolically expensive and there is no light to hide from.

Deep-slope catsharks are generally solitary outside mating, and there is no reason to expect the pale catshark to differ. It probably never leaves the bottom few metres of water, never rises above about 400 m, and never encounters a reef, a diver or a fishing line, which is why more than a century has passed without a second sighting.

Reproduction and lifespan

Every Apristurus whose reproduction is known is oviparous, and the pale catshark is assumed to follow the rule: the female lays egg cases in pairs, one from each oviduct, each a tough, flattened purse with tendrils at the corners that anchor it to the mud or to something upright on the bottom. Inside, the embryo lives entirely on its yolk for a long incubation, probably many months in water of 5 to 7 °C, and hatches as a fully formed miniature shark. The old description of this species "giving birth to live young" is wrong; catsharks do not do that, and the egg-laying mode is the safest inference on this page.

Nothing else is documented. The number of eggs a female lays in a year, the size at hatching, the age at maturity and the lifespan are all unknown, because the only specimen was a juvenile. Related deep-water catsharks mature at several years of age and probably live for a decade or two, and slow growth in cold water is the norm for the group, as our page on how long sharks live explains. Whether the holotype was a hatchling, a yearling or an older juvenile cannot be told from a preserved animal that has sat in alcohol in Amsterdam since the reign of Queen Wilhelmina.

Is the pale catshark dangerous to people?

Not in any conceivable way. The SharkSider database has no incident attributed to this species, and none could exist: the only pale catshark ever seen came up dead in a dredge at 655 m in 1899, and no diver, swimmer or fisherman has been in the water with one since. Even a fully grown adult would be a hand-sized shark with teeth made for shrimps, unable to break skin if it tried. It sits at the bottom of the Low category with every other deep-water catshark.

The sharks that matter to people in Indonesian waters are entirely different animals. The country's bite record, summarised on our shark attacks in Indonesia page, involves bull, tiger and reef sharks in shallow water, thousands of metres above the mud where the pale catshark lives. If you are diving the Makassar Strait, the catshark is the one shark you are guaranteed not to meet.

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 pale catshark as Least Concern in 2019, which sounds reassuring for a species known from one animal and needs explaining. The category does not mean the population is known to be healthy; it means the assessors found no identifiable threat. The Makassar Strait slope at 655 m lies below the reach of most Indonesian fisheries, which work the shelf and the upper slope with trawls, gillnets and longlines, and the assessors judged that the catshark is unlikely to be caught in numbers. Earlier assessments had listed it as Data Deficient, and in truth the data have not improved; only the reasoning has.

There is no protection specific to the species. It is not listed under CITES or the Convention on Migratory Species, Indonesia has no law covering it, and the deep-water shark closures that exist elsewhere have no equivalent in the Indonesian archipelago. The potential threats are the general ones for deep-sea fish: expansion of deep trawling and longlining as shelf stocks decline, and, in the long run, warming and deoxygenation of the slope waters it depends on.

For a shark this obscure, the most useful conservation step is simply to look for it. Deep-water surveys of Indonesian slopes have turned up many new Apristurus in the past two decades, and a second pale catshark, with a stomach, gonads and a tissue sample, would tell us more than the last century has. Our page on why sharks are endangered sets out why deep-sea species are so hard to protect.

Similar species and close relatives

Apristurus is the largest shark genus, with around forty species, most of them dark, soft-bodied slope dwellers that look alike and are told apart by snout length, fin positions, tooth counts and, increasingly, DNA. The Indo-Pacific holds many of them. The longnose catshark has the extreme snout of the group, the Japanese catshark is the common deep catshark of the north-western Pacific, and the longfin catshark is the biggest of the genus. In the Atlantic and eastern Pacific the brown catshark, the ghost catshark and the Panama ghost catshark show how the same body plan repeats on every slope.

The pale catshark's whitish colour invites comparison with the white ghost catshark of the north-east Atlantic, another pale Apristurus, but the resemblance is probably convergent rather than a sign of close kinship. Closer to home, Indonesia's shallow reef catsharks such as the coral catshark and the Bali catshark are only distant cousins in a different family; they live in a few metres of water, are striped or spotted, and are seen by divers every day, everything the pale catshark is not.

• Longnose Catsharkspecies profile
• Japanese Catsharkspecies profile
• Longfin Catsharkspecies profile
• Brown Catsharkspecies profile
• Ghost Catsharkspecies profile
• White Ghost Catsharkspecies 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 October 10, 2022 · Last updated September 22, 2026 · No incident attributed to this species in the SharkSider attack database, which is updated weekly.