Lollipop Catshark

• Maximum length28 cm (11 in); adults mostly 19–24 cm
• WeightNo reliable measurement (a few tens of grams)
• LifespanUnknown; no validated age data
• Depth range155–927 m (510–3,040 ft)
• DietShrimps and other crustaceans, small fish
• IUCN statusLeast Concern (assessed 2019)

How to recognise a lollipop catshark

No other shark in the eastern Pacific has this silhouette. The head of a lollipop catshark is grossly enlarged, taking up roughly a third of the total length, and it is dominated by an expanded gill region whose five slits arch forward rather than running straight down the side. Behind the head the body is a soft, almost gelatinous cylinder that narrows steadily into a thin tail, which is what earned the species its name: seen from above it looks like a lollipop on a stick, or a tadpole. The skin is loose and watery, the muscle thin, and freshly trawled specimens sag in the hand in a way that no reef shark ever would.

The colour is a uniform pale brownish grey, a shade lighter below, with whitish margins on the dorsal, pectoral and pelvic fins. The eyes are large for the head and shine an iridescent green under a lamp, the reflective layer that gathers whatever light reaches the slope. There are two small dorsal fins set well back, the first above the pelvic fins, and a long, low tail with no distinct lower lobe.

The mouth is short but wide, with papillae covering the tongue and the roof of the mouth. The teeth differ between the jaws: those in the upper jaw carry a straight central cusp with small side cusplets, those in the lower jaw a cusp that curves inward. Older books file the genus under Scyliorhinidae; modern classifications, following the lack of a bony crest above the eye, place it with Apristurus, Galeus and Parmaturus in the deepwater catshark family Pentanchidae. The only look-alike in its range is the peppered catshark, which is slimmer, darker and speckled and has a normal-sized head.

How big is a lollipop catshark?

This is one of the smallest sharks alive. The largest specimen on record measured 28 cm (11 in) in total length, and most adults trawled from the Gulf of California fall between 19 and 24 cm. Males are mature from about 19 cm; females mature at a similar length, and the difference between the sexes is slight beyond the claspers. Pups are around 10 cm (4 in) when they enter the world, already carrying the swollen head that marks the species.

Nobody has published a weight for the species, and given the watery, low-density body it would be modest: a full-grown fish is lighter than a bar of soap. That gelatinous build is not weakness but economy. Muscle is expensive to maintain where food is scarce and oxygen scarcer, and a small shark that ambles over the mud has little use for the power of a mako.

Because so few specimens have been measured, growth rates and the size of the very largest females remain unknown. On the size bar below it barely registers against the 1.8 m diver; it belongs in the same class as the dwarf lanternshark and the other entries on our list of the smallest sharks.

Where lollipop catsharks live

The known range is one of the smallest of any shark: the Gulf of California (the Sea of Cortez) and the Pacific coast of the southern Baja California peninsula, all within the waters of Mexico. Charles Henry Gilbert described the species in 1892 from specimens dredged by the US Fish Commission steamer Albatross in the Gulf, and the great majority of records since have come from the same basin, mostly from shrimp and research trawls in its central and southern reaches.

It lives on the bottom of the outer continental shelf and upper slope at 155 to 927 m (510 to 3,040 ft). The water at those depths in the Gulf is cold, dark and, above all, low in oxygen: the eastern Pacific oxygen-minimum zone is one of the most severe on Earth, and between roughly 300 and 800 m the dissolved oxygen falls to levels that would suffocate most fish. The lollipop catshark is one of the few sharks that treats that layer as home rather than as a barrier, which explains why it is so rarely caught alongside other sharks.

Sightings outside Mexico are doubtful. A second, still undescribed species of Cephalurus is known from the slope off Peru and Chile, and records from Central America may belong to it rather than to C. cephalus. The map below shows the confirmed distribution; none of our country guides lists the species, because it never comes near a beach.

What lollipop catsharks eat

The stomachs of trawled specimens hold mostly crustaceans: small shrimps, mysids and amphipods that live on and just above the mud of the slope. Small bony fish turn up less often, presumably taken when a sluggish or dying one comes within reach. The mouth and teeth agree with that menu. A wide gape, cusps that grip rather than cut and papillae lining the palate are the equipment of a fish that sucks in and holds small prey, not one that bites pieces from anything larger than itself.

Hunting in the oxygen-minimum zone has to be cheap. A lollipop catshark cannot afford sustained chases, so the picture from its anatomy and from what is known of related deepwater catsharks is of a slow forager cruising a few centimetres above the bottom, locating prey by smell and by the electrical sense of the ampullae of Lorenzini on its broad snout, then closing the last distance with a short lunge and suction. The large eyes probably matter less for finding food than for spotting the faint glow of bioluminescent animals and the shadow of anything bigger.

Feeding rates are unknown, but small deep-sea sharks generally eat little and digest slowly, and a single meal of shrimp may sustain one for days. The species has never been kept alive long enough for anyone to watch it feed, so this is inference from bodies rather than observation.

Behaviour and adaptations to low oxygen

The defining adaptation of this shark is its gill apparatus. The enormous head houses gill chambers far larger, in proportion, than those of any shallow-water catshark, with long gill filaments and wide slits that let it strip oxygen from water that holds very little. That is the point of the tadpole shape: the animal is, in effect, a set of gills with a small body attached. Together with a low metabolism, a light skeleton and muscle that is little more than a thin sheath, it lets the lollipop catshark live in the core of the oxygen-minimum zone where predators and competitors cannot follow. Our page on how sharks breathe explains the mechanics that this species pushes to the limit, and the gills page covers the structure itself.

Nothing is recorded of its social life, and there is no reason to expect much of one; catsharks are solitary by habit, and trawl catches of this species are usually single fish or a few at a time. Whether it moves up and down the slope with the seasons or with the shifting edge of the oxygen-poor layer is unknown. The large eyes with their green reflective sheen suggest that light still matters at the shallower end of its range, and a colour that matches the mud suggests that it relies on stillness rather than speed to avoid being eaten.

It is also a fragile animal: netted specimens are often damaged and none has survived in an aquarium, so this remains one of the least observed sharks on Earth.

Reproduction and lifespan

Here the literature disagrees, and it is worth being honest about that. The FAO catalogue and later accounts describe the lollipop catshark as one of the few catsharks that gives birth rather than laying eggs: females examined in early summer carried two embryos, one in each uterus, nourished by their yolk sacs, a mode called yolk-sac viviparity or ovoviviparity. Some databases instead list the species as oviparous, laying paired egg cases like its relatives. No modern study has settled the question, and the truth may be that the embryos are retained in thin capsules until very late, blurring the line between the two.

What is agreed is that the litter is tiny, probably two pups, that they are born at around 10 cm, and that birth seems to fall in the early summer months in the Gulf of California. Both sexes mature at roughly 19 cm, so a pup needs to less than double its length to breed, which for a shark is a short road to adulthood.

Nobody has aged a lollipop catshark. Its vertebrae are poorly calcified, growth bands are hard to read in small deep-sea sharks generally, and no tagging has ever been attempted. Small catsharks of this kind are thought to live for perhaps a decade or two, but for this species the only honest answer to how long sharks live is that we do not know.

Are lollipop catsharks dangerous?

Not in any way. A lollipop catshark is shorter than a ruler, has a mouth designed to suck in shrimps, and spends its life hundreds of metres down in water so poor in oxygen that no diver could visit it without a submersible. No swimmer, surfer or spearfisher has ever encountered one alive, and the SharkSider attack database has no incident attributed to the species; the records for Mexico involve bull, tiger and white sharks, never a catshark.

The only people who handle the species are shrimp trawler crews and biologists sorting their catch, and the risk there runs entirely the other way: the shark is usually dead or dying by the time it reaches the deck, its soft body crushed under the weight of the net. If you ever hold one, you are far more likely to damage it than it is to damage you, and the sensible thing is to photograph it and put it in the fixative jar.

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 lollipop catshark as Least Concern in 2019. That verdict rests on two things: the species has no commercial value and is not targeted by anyone, and a good part of its depth range lies below the reach of the deepwater shrimp trawls that work the Gulf of California. Fish taken shallower than about 300 m are discarded, almost always dead, but the catch appears small relative to the population. There is no listing under CITES or the Convention on Migratory Species and no species-specific protection in Mexican law.

The caveats are real. A range that fits inside one Mexican gulf leaves the species exposed to any regional change, and the oxygen-minimum zone it depends on is expanding and intensifying as the ocean warms, which could squeeze it against the shelf in ways nobody can yet predict. Population size and trend are unknown because there is no survey that counts it. Mexico's shrimp fishery has reduced its effort since the 2000s, which helps, and the northern Gulf includes a large marine protected area, though that lies mostly shallower than the shark's range.

The practical position is that the lollipop catshark is probably safe for now but poorly monitored, a common state for deep-sea sharks and one that our guide to why sharks are endangered discusses at length. Any expansion of deep trawling in the Gulf would need to be watched closely.

Similar species and close relatives

Cephalurus stands alone within the deepwater catsharks: a genus with one named species and a second, undescribed one from the slope off Peru and Chile that is slightly larger and darker. Its closest relatives in the family Pentanchidae are the other eastern Pacific slope-dwellers. The filetail catshark of California and Mexico is longer and firmer, with a saw-edged ridge of enlarged denticles along the top of its tail, and it shares the lollipop catshark's tolerance for low oxygen. The brown catshark and the longnose catshark, both Apristurus, have long flattened snouts and normal-sized heads, and the Panama ghost catshark replaces them further south. The peppered catshark, a Galeus, shares the Gulf of California itself.

The jaguar catshark of the Galápagos belongs to Bythaelurus, another genus in the same family, and shows what a lollipop catshark might look like with an ordinary head: a stout little bottom shark with a rounded snout. None of these can be confused with Cephalurus once you have seen the head. See the types of sharks guide for how the catshark families fit into the wider group.

• Filetail Catsharkspecies profile
• Brown Catsharkspecies profile
• Peppered Catsharkspecies profile
• Panama Ghost Catsharkspecies profile
• Longnose Catsharkspecies profile
• Jaguar 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 September 9, 2022 · Last updated September 22, 2026 · No incident attributed to this species in the SharkSider attack database, which is updated weekly.