WHALE SHARK
FACTS.

Top 10 whale shark facts

1. Whale sharks are the world’s biggest fish — the largest widely accepted length estimate is 18.8 meters (62 ft).
2. They eat some of the ocean’s smallest animals: shrimp, fish eggs, krill, crab larvae, and other tiny prey.
3. They are filter feeders, with a throat only about the size of a baseball.
4. Whale sharks are harmless to people. They do not hunt anything larger than small fish, and their tiny teeth play no part in feeding.
5. Individual sharks can cover thousands of kilometers: two sharks tagged off Madagascar by the Madagascar Whale Shark Project traveled 3,414 and 4,275 km (2,120 and 2,660 mi).
6. They dive far deeper than once thought — one tag registered a dive of at least 1,978 meters, the deepest yet recorded for a whale shark.
7. Their skin is up to 15 cm (6 in) thick — the thickest in the animal kingdom.
8. Scientists have examined only one pregnant whale shark. She was carrying about 300 embryos.
9. Nobody knows how long they live. Published estimates run from 80 to 130 years.
10. Every whale shark has a unique spot pattern, like a fingerprint. More than 17,000 have been identified.

How big is a whale shark?

Whale sharks are the biggest fish in the world, and the largest living cold-blooded animals. The largest widely accepted length estimate is 18.8 meters (62 ft), and one reported catch weighed 34 metric tons (37 US tons). Less reliable reports describe sharks around 20 meters.

The second-largest fish, the basking shark, reaches about 12.3 meters. Whale sharks may also be the largest fish that has ever lived, but that claim has grown less certain: megalodon was long estimated at 14.2–15.3 meters, and later reconstructions put it at around 20 meters, then as much as 24.3. The all-time record is now an open question.

Whale sharks stayed mysterious for a long time. Andrew Smith described the species in 1828, and a 1986 review could gather only 320 records from all of history up to 1985. We know far more now because whale sharks gather where food is plentiful. For more on their size, see our guide to whale shark size.

What do whale sharks eat?

Whale sharks feed on some of the smallest animals in the sea: shrimp, fish eggs, krill, copepods, and crab larvae, known together as zooplankton, plus small fish such as anchovies. Their prey must be small because a whale shark’s throat is only about the size of a baseball.

The filter pads in their mouths have pores just over a millimeter wide, yet the sharks routinely swallow eggs smaller than that — how they keep hold of them is unsolved. Filtering only pays where prey is dense: beside feeding sharks at Mafia Island, Tanzania, we measured plankton ten times denser than the surrounding water.

Surface feeding is only part of the story. Combining stomach contents from stranded sharks with the fat signatures of living ones, we found that Mozambican whale sharks also feed at night: their stomachs held mysids (small shrimp-like crustaceans) that rise toward the surface after dark, and their fat signatures suggest they take deep-water prey as well.

Read the full chapter: whale shark feeding and diet.

Are whale sharks dangerous?

No. Whale sharks are filter feeders with tiny teeth they don’t use for feeding, and they pose no threat to swimmers or divers. The risk runs the other way: boat strikes and careless tourism injure sharks, which is why good encounters keep a respectful distance, never touch, and let the shark set the pace.

Where do whale sharks live?

Whale sharks live in all tropical and warm temperate oceans, with their core range between about 30°N and 30°S. Based on the current IUCN Red List assessment led by our scientists, about 75% of the global population lives in the Indo-Pacific and 25% in the Atlantic.

A 2017 global analysis recognized about 20 coastal sites with predictable gatherings; more than 50 are now known, and almost everything we know comes from them. The largest, off Mexico’s Yucatán coast, has held up to 420 sharks in just 18 km². As the ocean warms, whale sharks are expected to shift poleward and into busier shipping lanes — with occasional records already as far north as Portugal.

Males and females use the ocean differently. Young males of 4 to 8 meters dominate most known feeding areas; as they grow, they seem to spend more time offshore, and adults are rarely seen at coastal sites. Maturity size varies by sex and population. Adult females are rarely seen at all — with one exception. At Darwin Island in the Galápagos, where we work with the Galapagos Whale Shark Project, more than 95% of the sharks we identify are adult females of 10 to 14 meters, the only place big females can reliably be found.

Read the full chapter: whale shark migration and movements.

How far do whale sharks travel?

Warm tropical water often contains little food, so whale sharks cover enormous distances between meals. Off Madagascar, two of our tagged sharks covered 3,414 and 4,275 km (2,120 and 2,660 miles). Tracking from five Indian Ocean sites has detected sharks in 24 countries and the high seas.

Yet most of the time they don’t go far, and they come back. Sharks from each of those Indian Ocean sites stayed in largely separate areas rather than mixing freely, which is why we argue for regional management rather than treating a whole ocean as one population. How they navigate is still unknown.

How deep can whale sharks dive?

At least 1,978 meters (6,490 feet) — the deepest dive yet recorded for a whale shark. Our scientists and collaborators logged it in the Coral Sea in 2026 using a custom deep-rated tag, and the record suggests the shark may have reached 2,527 meters. The previous confirmed maximum was 1,928 meters, the deepest of 38 shark and ray species compared. For years the honest answer was “deeper than we could measure”: standard satellite tags max out around 2,000 meters.

Why they go so deep is unsettled. Food is one candidate: the twilight zone, a few hundred meters down, holds trillions of lanternfish. But prey mapping at Ningaloo found sharks diving through dense prey without lingering, so navigation and efficient travel remain live explanations.

Whale sharks are mostly seen in water between about 23°C and 30°C, but deep dives take them close to freezing. Their bulk keeps them warm: muscle temperature changes far more slowly than the water around them, which is what lets a tropical fish spend hours below 1,000 meters.

More on diving and tracking in the movements chapter.

Whale sharks have the thickest skin in the world

Whale shark skin is up to 15 cm (6 in) thick — the thickest in the animal kingdom. Its dense, rubbery inner layer is armor, insulation, and structural support. An animal trying to bite a whale shark mostly gets a mouthful of gristle.

Few predators attack them. Killer whales are the only animals documented killing an adult, and great white sharks are a probable predator; both are likely rare. Young whale sharks are far more vulnerable — baby whale sharks have been found in the stomachs of blue sharks and blue marlin.

Read the full chapter: whale shark anatomy.

How do whale sharks reproduce?

Scientists have examined only one pregnant whale shark: a 10.6-meter female caught off Taiwan in 1995, nicknamed “megamamma,” carrying about 300 embryos, more than twice the next-largest shark litter on record. Genetic work on 29 of those embryos later showed they all shared one father. Pups are born free-swimming at around 60 cm long, about 5% of their mother’s length: the smallest newborn relative to its mother of any shark.

In 2023, work we contributed to in the Galápagos brought underwater ultrasound and blood sampling to free-swimming sharks for the first time, finding developing follicles but no embryos. Where pups are born is still unknown. Read more in our guide to whale shark reproduction.

How long do whale sharks live?

Published estimates run from about 80 to 130 years, and the only firmly validated age is much lower: a 10-meter female confirmed at 50 years. Ten years of measurements in the Maldives put male lifespan at about 130 years, while growth bands in vertebrae from Taiwanese fisheries suggested closer to 80. Nobody knows which is right, and the reason is that length stops telling you age: whale sharks appear to stop growing once they reach their own maximum size. A shark called Stumpy has returned to Ningaloo Reef for over two decades at roughly the same 7.4 meters.

Read the full chapter: how long whale sharks live.

How do scientists tell whale sharks apart?

Each whale shark’s spot pattern is unique, so a clear photo can identify that shark for life. Photographs from researchers, dive operators, and tourists feed a global whale shark database now hosted on Sharkbook.ai, which holds more than 17,000 identified sharks. The analysis we co-authored of its first 22 years — nearly 30,000 encounters from 54 countries — showed the pattern that shapes the field: most identified sharks are young males that return to the same site rather than crossing borders. Even the largest feeding areas have yielded only a few thousand identified sharks each, over many years of surveys.

Why are whale sharks endangered?

Whale shark numbers have fallen by 50–79% over the past three generations — about 120 years — driven mainly by fisheries. The current IUCN Red List assessment, led by MMF scientists, keeps the species Endangered and still declining. We also led its first Green Status assessment, which gave the whale shark a Species Recovery Score of about 29%. That is a measure of recovery, not a headcount: it scores each part of the species’ range for whether whale sharks are absent, present, viable, or ecologically functional, and 100% would mean fully functional everywhere they once occurred.

Southern Mozambique shows what that looks like on one stretch of coast. Our 15-year survey off Praia do Tofo recorded an 87% drop in sightings and an 89% fall in abundance, with sharks of 7 meters or more down by 99%. Mafia Island in Tanzania is the counterexample — stable, with high survival and no detectable trend, though only a change of about 30% would have been detectable over that period — which is why we monitor the same places for decades rather than years.

Ships are the threat that took longest to see. An international study we contributed to found 92% of whale sharks’ space use overlaps with heavy large-vessel traffic, and that tagged sharks sometimes sink, probably dead, after crossing busy routes. Because those animals are never recovered, ship strikes may explain why numbers keep falling despite protection. A follow-up we co-authored ranked the sites where slowing or rerouting ships would help most — most small enough for mitigation to cost industry little.

Whale sharks now hold the strongest protection either international wildlife convention offers: Appendix I of the Convention on Migratory Species since 2017, and Appendix I of CITES — a full ban on commercial international trade — in force from 5 March 2026. Legal protection is only the start: bycatch, boat strikes, and habitat change still kill whale sharks. Our Global Whale Shark Program works on the research, monitoring, and policy that turn protection into recovery.

Read the full chapter: why whale sharks are endangered.