The honeycomb izak, Holohalaelurus favus, is a small catshark endemic to a narrow strip of the western Indian Ocean off South Africa and southern Mozambique, living on the outer shelf and upper slope at roughly 200 to 740 metres. It is named for the dense dark reticulations on its back, which form a honeycomb over a yellowish-brown ground colour.
It is listed as Endangered on the IUCN Red List, and the reasoning behind that listing is unusually stark: no confirmed specimen has been collected since the 1970s, despite decades of trawl surveys across the ground where it used to be taken.
- Scientific nameHolohalaelurus favus
- RangeKwaZulu-Natal to Mozambique
- IUCN statusEndangered
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The shark and its name
The honeycomb izak is one of the izak catsharks, a small genus confined to the waters around southern and eastern Africa. Favus is the Latin word for a honeycomb, and it refers to the markings: a lattice of dark lines and blotches over a pale tan back that really does look like comb seen from above. In South Africa it is also called the Natal izak, after the province off which it was found.
It sits in the catsharks, order Carcharhiniformes, the same broad group as the leopard catshark and the shysharks of the Cape. Some recent classifications move Holohalaelurus and its relatives into a separate family of deepwater catsharks rather than leaving them with the shallow-water scyliorhinids, which is a reasonable reflection of how differently these fish live.
For most of the twentieth century the species was not treated as a species at all. Specimens were filed under the far more common izak catshark, and the two were only properly separated in a revision of the genus published in the 2000s. That is part of why so little is known about it: by the time it had a settled identity, nobody was catching it any more.
Size, shape and the weight that cannot be right
This is a small shark. Published lengths put mature males at around half a metre and females smaller, which makes it comparable to a puffadder shyshark or any of the other slope catsharks off southern Africa. The head is broad and flattened with a blunt snout, the eyes are oval and set high on the head with ridges above them, and flaps of skin partly cover the nostrils.
One figure that circulates about this species should be discarded. Several accounts give its weight as about 66 pounds, roughly 30 kilograms. Nothing half a metre long and built like a catshark weighs that; a shark of this length and shape is a matter of a kilogram or two. No reliable published weight exists for Holohalaelurus favus, and it is better to say so than to repeat a number that fails the first sanity check.
The markings are the identification. Adults carry dark reticulations and blotches of varying size across the back and the upper surface of the fins, and the pattern is reported to change as the animal grows, which has contributed to the long confusion with its commoner relative. The skin, like that of every shark, is covered in placoid scales rather than the bony scales of an ordinary fish.
A very small range in deep water
Every confirmed record comes from a short section of the western Indian Ocean: the shelf edge and upper slope off KwaZulu-Natal in South Africa, extending north into southern Mozambique. That is a tiny distribution for a shark, a few hundred kilometres of coast, and it is the main reason the species is vulnerable to anything that disturbs that ground.
Depths of roughly 200 to 740 metres put it well below the reef and inshore habitats where South Africa's better-known small sharks — the pyjama shark, the brown shyshark, the Natal shyshark — are found. It is a bottom-associated animal on the slope, and juveniles have been reported from deeper water than adults, which would be an unusual arrangement if it holds up.
Diet is known from stomach contents of the historical specimens: small bony fishes, cephalopods, crustaceans, hydrozoans and polychaete worms. That is the standard menu for a small slope-dwelling catshark and implies an animal that works the sediment rather than chasing anything down.
Endangered, and possibly already gone
Reproduction has never been observed. Every other member of the genus is oviparous, laying tough egg cases on the bottom, so the honeycomb izak is assumed to do the same, but there is no description of an egg case, a hatchling or a clutch size for the species. Nor is there a population estimate, a growth rate or an age at maturity.
What there is instead is an absence. The Red List assessment that places the species in the Endangered category rests on the fact that no confirmed specimen has been collected since the 1970s, while the shelf and slope off KwaZulu-Natal have been trawled repeatedly in the decades since. Prawn and demersal trawling over exactly this depth band is the obvious suspect, and it is the same pressure that has reduced several of its congeners.
Nobody has formally declared the species extinct, and small deep-water sharks have been rediscovered before. But the honeycomb izak is a useful corrective to the idea that shark decline is only about the large, famous species — see why sharks are endangered for the wider picture, and the guide to shark species or the shark terms glossary for the rest of the group.
Frequently asked questions
How big is a honeycomb izak?
Small. Published measurements put mature males at around half a metre in length, with females somewhat shorter, which is typical for a slope-dwelling catshark. Claims that the species weighs about 66 pounds are not credible for an animal of that size and should be ignored; no reliable weight has been published.
Where does the honeycomb izak live?
Only in a narrow band of the western Indian Ocean, along the shelf edge and upper slope off KwaZulu-Natal in South Africa and reaching north into southern Mozambique. Records span depths of roughly 200 to 740 metres, which places it well below the reefs where the region's shyshark species live.
Why is the honeycomb izak endangered?
Because it has a very small range and has not been confirmed in catches since the 1970s, despite repeated trawl surveys of the ground it used to come from. Demersal and prawn trawling across that depth band is the suspected cause. The IUCN Red List places the species in the Endangered category.
How did the honeycomb izak get its name?
From the markings on its back. The Latin species name favus means honeycomb, and the dense lattice of dark lines and blotches over a yellowish-brown ground does resemble comb seen from above. It is also called the Natal izak, after the South African province off which it was collected.
Does the honeycomb izak lay eggs?
Almost certainly, though it has never been observed. Every other species in the genus is oviparous, laying tough egg cases on the sea floor, so the honeycomb izak is assumed to breed the same way. No egg case, hatchling or clutch size has ever been described for it.
References
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Published October 18, 2022 · Last updated September 23, 2026 · Part of the Types of Sharks section.
