Whale Shark
Rhincodon typus
Not a whale. Not a mammal. Just the biggest fish in the world.
Everyone else on this site is a mammal — warm-blooded, air-breathing, milk-drinking. The whale shark is none of those. It's a fish, it breathes water through five enormous gill slits, its skeleton is made of cartilage instead of bone, and its tail stands up on its edge instead of lying flat. It got the whale part of its name purely for being the size of one.
On the conservation status
Listed as Endangered by the IUCN since 2016, and reassessed as Endangered again in 2025. The population is still falling and is thought to have at least halved, mostly because of targeted fishing that only began in the 1980s.
- Length
- Usually under 12 m (40 ft); the record is about 20 m
- Weight
- Up to about 40,000 kg, by some estimates
- Lifespan
- Unknown — maybe 60–100 years
- Diet
- Plankton, krill, fish eggs, small fish
- Dive depth
- Recorded below 1,900 m
- Class
- Fish — not a mammal
The good stuff.
How to tell a fish from a whale
Look at the tail. A whale's fluke is horizontal and beats up and down; a shark's tail is vertical and sweeps side to side. Then check for gill slits instead of a blowhole. Whale sharks have five on each side, and each one is bigger than your head.
Three thousand teeth, and it never chews
A whale shark has around 300 rows of tiny teeth, and doesn't chew with any of them. It filters instead — pushing something like 6,000 litres of water an hour through pads behind its gills and keeping whatever gets caught.
It has teeth on its eyeballs
Really. In 2020 researchers found the eyes are covered in hundreds of tiny tooth-like scales called dermal denticles. The whale shark also has no eyelids, so it protects its eyes by pulling them back into their sockets instead.
NASA software counts them
Every whale shark's pattern of spots is unique, like a fingerprint. Researchers identify individuals using an algorithm originally written to match patterns of stars in Hubble Space Telescope images — the maths turns out to be identical.
Babies are born, not hatched
The only pregnant whale shark ever examined, caught off Taiwan, was carrying 304 pups at different stages of development — the biggest litter known from any shark. They all seem to have had the same father, which suggests she could store sperm. How often whale sharks give birth is still unknown.
The thickest skin in the ocean
Up to 15 cm of it — among the thickest skin of any animal alive. Underneath, they are famously gentle. Divers swim alongside them and the shark mostly ignores everybody.
Wait, really?
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Its mouth is about a metre wide, and it sits right at the front of the head rather than underneath like most sharks.
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In the Philippines it's called butanding; in Mexico, pez dama — the domino fish, for the spots.
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At most of the famous feeding spots, nearly every whale shark is a young male. Where the grown-up females spend their time is still mostly a mystery.
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Whale sharks gather in the hundreds off Mexico's Yucatán every summer for a plankton feast called the afuera.
What it sounds like
Silent, as far as anyone can tell. Whale sharks have no known vocalisations — no songs, no clicks, nothing. It's one of the loudest differences between them and the mammals on this site.
Where you might see one
Ningaloo Reef in Western Australia, Isla Holbox and Isla Mujeres in Mexico, Donsol in the Philippines, and the Maldives all year.
The trouble
- Fishing — they are still caught and sold in some countries
- Ship strikes — they feed at the surface, right where the hulls are
- Fishing nets — tuna boats sometimes set nets around them on purpose, because tuna swim alongside them
- Boat propellers and crowding from unmanaged tourism
One real thing
If you ever get to swim with one, pick an operator that follows the rules: no touching, no riding, no flash, and a proper distance. Badly run tours push the sharks off their feeding grounds.
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