Whale Shark (Rhincodon typus): Facts, Size and Diet

What does a whale shark look like?

The whale shark has a broad, flat head and a huge mouth set right at the front of the snout, rather than underneath as in most sharks. In a large adult the mouth can be about 1.5 m (5 ft) wide. The small eyes sit at the corners of the head, with spiracles, small openings that help with breathing, just behind them. Five pairs of large gill slits run down each side.

The back and sides are dark gray, blue-gray or brownish, covered with pale spots and thin pale stripes in a checkerboard pattern, while the belly is white. Three prominent ridges run along each side of the body toward the tail. The tail fin is tall and crescent-shaped, with a larger upper lobe.

The skin is extremely tough, up to about 10–15 cm (4–6 in) thick in big sharks, and covered with tiny tooth-like scales called dermal denticles. In 2020, researchers in Japan reported that whale sharks even have denticles on their eyeballs and can pull their eyes deep into their sockets, which probably protects them from damage. The mouth holds more than 300 rows of tiny teeth, each only a few millimeters long, but they play no known part in feeding.

The whale shark is the only living member of its family. It belongs to the carpet sharks, the same order as nurse sharks and wobbegongs.

How big do whale sharks get?

Whale sharks are the largest living fish and the largest animal of any kind that is not a whale. Their maximum size is still uncertain, because very large sharks are hard to measure accurately in the water and rarely end up on land. Most sharks seen at coastal feeding sites are young males of about 4–8 m (13–26 ft).

A ten-year study at Ningaloo Reef in Western Australia, published in 2020, found that males reach an average adult length of about 8–9 m (26–30 ft) and that females grow larger, although few big females have been measured. The most reliable record is a female from the Arabian Sea, reported in 2001, with an estimated total length of 18.8 m (62 ft). Older reports of 20 m (66 ft) or more lack solid documentation.

Very few whale sharks have ever been weighed. A shark of about 11–12 m (36–39 ft) found dead off Karachi, Pakistan, in 2012 was reported to weigh around 15 tonnes. The second-biggest fish, the basking shark, is much smaller, as the ranking of the largest fish in the world shows.

Where do whale sharks live?

Whale sharks live in tropical and warm-temperate seas around the world, mostly between about 30° N and 35° S and usually in water warmer than about 21 °C (70 °F). Strays have turned up as far north as the Bay of Fundy in Canada. They use both the open ocean and coastal waters, and genetic studies point to two main populations, one in the Atlantic and a larger one in the Indian and Pacific Oceans.

They are best known from seasonal gatherings at places where food becomes plentiful. These include Ningaloo Reef (roughly March to July), the Yucatán Peninsula of Mexico (roughly May to September), La Paz and Bahía de los Ángeles in the Gulf of California, Belize, Djibouti, Mozambique, the Maldives, the Philippines and Qatar. At Darwin Island in the Galápagos, most of the sharks seen are large adult females, many of which appear to be pregnant.

Whale sharks are great travelers. A female tagged near Coiba Island, Panama, in 2011 was tracked for more than 20,000 km (12,400 mi) across the Pacific toward the Mariana Trench, one of the longest fish journeys ever recorded; others feature in the list of the longest animal migrations. Although they spend much of their time in the top 200 m (660 ft), tagged sharks have dived to 1,928 m (6,325 ft).

How do whale sharks feed?

The whale shark is one of only three filter-feeding sharks, along with the basking shark and the megamouth shark. It eats plankton such as copepods and krill, fish and coral eggs, crab larvae, small squid and small schooling fish such as sardines and anchovies. Water flows into the mouth and out through the gills, while 20 spongy filter pads, thought to be modified gill rakers, separate the food.

Unlike the basking shark, which simply swims with its mouth open, the whale shark is an active feeder. It can swim forward with its mouth open, gulp water by suction while almost stationary, or hang vertically at the surface and suck in food. A study off Mexico’s Yucatán coast estimated that whale sharks there spent about 7.5 hours a day feeding at the surface. Feasts on spawning fish and corals, and how much a shark eats, are covered in What do whale sharks eat?

Behavior and spot patterns

Whale sharks are usually solitary, but dozens or even hundreds may gather where food is concentrated; more than 400 were counted off the Yucatán in 2009. They swim slowly, usually at about 2–5 km/h (1–3 mph). Tracking suggests that they often return to the surface after deep dives into cold water, possibly to warm up.

The pale spots behind the gills form a pattern unique to each shark, like a fingerprint. In 2005, researchers adapted a computer method used by astronomers to match star patterns, which lets photos of a shark’s spots be matched automatically. Photos taken by divers and tourists around the world now feed an online library, allowing scientists to track individual sharks for years without tagging them.

Reproduction and lifespan

Much of the whale shark’s life cycle is still a mystery. Mating is rarely seen, although an attempt was filmed from the air at Ningaloo Reef in 2019. No one has watched a whale shark give birth, and where females have their young is unknown.

What is known comes partly from a female about 10.6 m (35 ft) long caught off Taiwan in the 1990s, which carried about 300 embryos at different stages. This showed that whale sharks are ovoviviparous: the eggs hatch inside the mother, and the pups are born live at about 40–60 cm (16–24 in). Genetic tests on some of the embryos found that they shared one father, suggesting that females can store sperm.

Whale sharks grow and mature slowly. Males appear to take around 25 years to mature, and females probably longer. A 2020 study used carbon from nuclear bomb tests of the 1950s and 1960s, recorded in the backbone, to confirm that growth bands form once a year; a 10 m (33 ft) female was about 50 years old. Lifespan estimates range from about 80 to 130 years.

Predators and threats

Adult whale sharks have few natural predators, but orcas have been seen attacking them in the Gulf of California. Young sharks can fall prey to blue sharks, tiger sharks and blue marlin.

People are the main threat. Whale sharks have been caught for their meat, fins and liver oil, especially in parts of Asia, and are taken as bycatch in nets set for tuna. Because they feed slowly at the surface, they are also struck by ships, and many carry propeller scars. A study published in 2022 found that whale shark movements overlap heavily with large-ship traffic, and that some satellite tags stopped transmitting in busy shipping lanes, suggesting that fatal collisions go largely unrecorded. Plastic pollution and poorly managed tourism add to the pressure.

Conservation status

The IUCN Red List has listed the whale shark as Endangered since 2016, up from Vulnerable. The assessment estimated a global decline of more than 50% over about 75 years, with losses of around 63% in the Indian and Pacific Oceans and more than 30% in the Atlantic.

International trade has been controlled under CITES Appendix II since 2003. The Philippines banned fishing and selling whale sharks in 1998, followed by India in 2001 and Taiwan in 2007. Tourism now makes living whale sharks worth far more to many coastal communities than dead ones, a strong reason for local protection.

Are whale sharks dangerous to people?

No. Whale sharks are gentle filter feeders that do not attack people, and snorkelers swim with them at many sites. The only real risk comes from their size: a large shark can bump a swimmer by accident or strike with its powerful tail. Codes of conduct ask swimmers to keep several meters away and never touch the sharks, as explained in Are whale sharks dangerous?

Myths and facts

Myth: whale sharks are whales. The whale shark is a true shark, a fish with gills and a skeleton of cartilage. It gets its name from its enormous size and whale-like way of filtering food, as explained in Is a whale shark a whale?

Myth: a whale shark could swallow a person. Its mouth is huge, but it strains small food and swallows nothing larger than small fish. A diver near its mouth is not prey.

Fact: many cultures have named its spots. In Madagascar it is called marokintana, meaning “many stars”, after the pattern on its back, and in the Philippines it is known as butanding.