The bigeye sand tiger, Odontaspis noronhai, is a rare deep-water shark of the family Odontaspididae, recorded from tropical and warm-temperate parts of both the Atlantic and the Pacific at depths of roughly 60 to 1,000 metres. The largest measured specimen was about 3.6 metres, or 12 feet.
It is the odd one out in a small family. Where the sand tiger shark is a coastal animal familiar from aquariums, the bigeye sand tiger has almost never been seen alive, and nearly everything on record comes from a few dozen specimens taken as bycatch on deep longlines.
- Scientific nameOdontaspis noronhai
- Largest measuredAbout 3.6 m (12 ft)
- Depth rangeRoughly 60–1,000 m
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A shark described from one fish
The species was named in 1955 by the German-born ichthyologist Günther Maul, working at the museum in Funchal, Madeira. His description rested on a single female of about 1.71 metres caught locally in April 1941, and he dedicated the name to Adolfo César de Noronha, a former director of that museum. For more than three decades afterwards the holotype remained the only specimen anyone had examined.
It belongs to the sand tiger family, Odontaspididae, within the mackerel sharks — the same order as the great white, the threshers and the megamouth. The family holds only three living species, and the genus Odontaspis holds two: this one and the smalltooth sand tiger, which is also a deep-water animal but considerably better documented.
Records have accumulated slowly since the 1980s, mostly from longline vessels fishing for tuna and swordfish. They come from the Gulf of Mexico and off Texas, from eastern Florida and southern Brazil, from the Mid-Atlantic Ridge and Madeira, and from the central Pacific. The pattern points to a shark that is genuinely widespread in warm oceans rather than confined to the southern hemisphere, as older accounts of the species had it, but which lives where almost nobody is looking.
How to recognise one
The colour alone separates it from most sharks in the sea. A bigeye sand tiger is uniformly dark, running from reddish brown to something close to chocolate, on the belly as well as the back. It has no countershading, which is the pale-underside arrangement that almost every shark in lit water depends on — one of several hints that this is an animal of genuine darkness.
The eyes are large, round, and have no nictitating membrane; the iris is orange with a vertical, greenish pupil. The snout is bulbous and the mouth is wide, extending well behind the eye, with jaws that can be thrown forward a long way. The teeth suit that mouth: long, narrow, exposed even when the jaws are closed, each with a single main cusp flanked by one small cusplet on each side. Small spiracles sit behind the eyes.
There are five pairs of gill slits and a notably large first dorsal fin, set well forward near the pectorals, with the second dorsal roughly half its size. Some specimens show dark trailing edges on the fins and a pale tip to the first dorsal. The overall shape is close to the smalltooth sand tiger, but the smalltooth is grey-brown, countershaded and smaller-eyed.
Where it lives and how deep it goes
Captures place the species between roughly 60 and 1,000 metres — from the outer edge of the continental shelf down into water that receives no daylight at all. Most records are from around and below 400 metres, over continental and island slopes as well as in open water far from any bottom, which is unusual for a shark of its build.
The pattern of catches suggests it follows the daily vertical migration that so much deep-sea life follows: rising toward the upper water column after dark to feed, dropping back into the dark layers by day. Large eyes with no protective membrane fit that life, as does the uniform dark colouring, which works where there is no bright surface to hide against.
How many there are is not known, and that is not a hedge — no population estimate exists for this species. What is on record is a global scatter of single fish, which is consistent either with a widespread but naturally sparse animal or with one that simply lives outside the reach of most fishing gear.
Diet, breeding and contact with people
Stomach contents from the few examined specimens point to bony fishes and squid, which is what the long grasping teeth would predict — they are built to hold slippery prey rather than to cut through it. Breeding has never been observed. Like the other mackerel sharks it is presumed to bear live young that feed on unfertilised eggs inside the uterus, a strategy called oophagy, but no pregnant female has been described in enough detail to confirm litter size. Males appear to mature at about 2.2 metres and females somewhere above three metres.
Contact with people is close to nil. The SharkSider incident database holds no record attributed to this species, which is unsurprising for a shark that spends its life hundreds of metres below any swimmer or diver. The only aggression on record involves a hooked animal thrashing while being brought aboard, which says more about the situation than the shark.
The IUCN Red List treats it as a species of least concern, on the reasoning that it is taken only occasionally as bycatch on tuna longlines and gillnets and that most of its depth range lies below heavy fishing pressure. That assessment rests on very little data, and it should be read as an absence of evidence of decline rather than as evidence of a healthy population. For the other end of the family, see the sand tiger sharks, and for more deep-water oddities the goblin shark, the crocodile shark and the bigeye thresher in our guide to shark species.
Frequently asked questions
How big does a bigeye sand tiger get?
The largest specimen measured was about 3.6 metres, or roughly 12 feet. Males appear to reach maturity at around 2.2 metres and females somewhere above three metres. The original description in 1955 was based on a female of 1.71 metres, which is a juvenile by those standards.
Where does the bigeye sand tiger live?
In warm parts of both the Atlantic and the Pacific, at depths of roughly 60 to 1,000 metres. Records come from the Gulf of Mexico, Texas, Florida, southern Brazil, Madeira, the Mid-Atlantic Ridge and the central Pacific, which suggests a wide range rather than one particular region.
Is the bigeye sand tiger dangerous to humans?
There is no realistic risk. The SharkSider database holds no incident attributed to the species, and the shark lives hundreds of metres below the depths swimmers and recreational divers use. The only reported aggression came from a hooked animal being hauled aboard a fishing vessel.
How is it different from the smalltooth sand tiger?
Colour is the quickest test. The bigeye sand tiger is uniformly dark reddish or chocolate brown with no pale underside, while the smalltooth sand tiger is grey-brown and countershaded. The bigeye also has larger, orange-irised eyes and a bulkier snout, and it is the rarer of the two by a wide margin.
Why is it so rarely seen?
Because of where it lives. Most of its depth range sits below the reach of trawlers and well below any diver, and it is picked up only as occasional bycatch on deep longlines set for tuna and swordfish. No population estimate exists for the species, and live observations are effectively non-existent.
References
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 24, 2022 · Last updated September 23, 2026 · Part of the Types of Sharks section.
