Whale Shark

The Whale Shark (Rhincodon typus) is a slow-moving, filter-feeding carpet shark and the largest known living fish. The most reliably recorded individual measured about 18.8 m, and most are smaller. It is by far the largest living animal that is not a whale, dolphin or porpoise.

Whale sharks have a broad, flat head with a very wide mouth at the front, rather than underneath, and two small eyes at the front corners. The skin is dark grey with a white belly, marked with pale spots and stripes that are unique to each individual. The skin can be up to 15 cm thick and is hard and rough to the touch. Three prominent ridges run along each side of the body.

They live in the open waters of tropical and warm-temperate seas, usually between about 30°N and 35°S, and are rarely found in water below 21 °C. A few public aquariums keep them, but in the wild they are ocean wanderers.

The Whale Shark was first distinguished in April 1828, after a 4.6 m specimen was harpooned in Table Bay, South Africa. Andrew Smith, a military doctor with British troops stationed in Cape Town, described it the following year.

The name refers to its appearance and huge size. It is a fish, not a mammal, and like all sharks it is not closely related to whales.

Whale sharks are one of the most ancient shark species still living. The earliest fossil teeth come from the Late Oligocene of South Carolina, US, and later teeth turn up more widely, including the eastern United States, southern France and Costa Rica. It is the only living species of its genus and family.

People first tried keeping one in 1934, in a netted-off bay in Izu, Japan, for about four months. The first aquarium attempt began in 1980 at Okinawa, Japan.

Despite their immense size, Whale Sharks are docile and pose no significant danger to humans. Younger ones are gentle and can play with divers.

They are active filter feeders, taking in plankton, krill, fish eggs and small fish such as sardines and anchovies. They feed either by swimming forward with the mouth open or by gulping water while stationary, and they have been seen apparently coughing to clear their filter pads. They have even been seen timing their arrival to mass fish spawning.

Whale sharks are highly migratory and travel thousands of miles. Large seasonal feeding gatherings occur at places such as Ningaloo Reef in Western Australia and off the Yucatan Peninsula in Mexico, where more than 400 gathered in 2009. Whale sharks tracked off the Yucatan Peninsula spent most of their time in the top 200 m but also made regular deep dives, and the deepest recorded dive reached 1,928 m.

Whale Sharks are estimated to live between 80 and 130 years, based on growth bands in their vertebrae and the growth rates of free-swimming sharks. They mature late; males are estimated to reach maturity at around 25 years.

Evidence suggests they can recover from major injuries, and their spot markings have been seen to reform over healed wounds. Their eyes are protected by tiny tooth-like denticles and by the ability to retract deep into the sockets.

Because of the way they feed, they are susceptible to swallowing microplastics, which have been found in their scat. Propeller scarring is widespread; one report found 65% of sharks in an area of Djibouti were injured.

Young, sick or injured Whale Sharks can be hunted by orcas, large sharks and blue marlin, but healthy adults have few natural predators.

This is general awareness only, not veterinary advice. If you find an injured or unwell wild animal, contact a vet or a wildlife rescue.

Is a whale shark a whale?

No. It is a fish, not a mammal, and like all sharks it is not closely related to whales. The name comes from its huge size and appearance.

How big do whale sharks get?

The most reliably measured individual was about 18.8 m long. Reports of 18 to 20 m exist, but the maximum size is uncertain, and most are smaller. Females appear to grow larger than males.

Are whale sharks dangerous?

No. They are docile and pose no significant threat to humans. Touching or riding them is forbidden in most countries because it can seriously harm them.

How long do whale sharks live?

Estimates range from about 80 to 130 years. The longest-lived in captivity had passed 26 years as of 2021.

What do whale sharks eat?

They filter plankton, krill, fish eggs and small fish from the water. Their many rows of tiny teeth play no part in feeding.

Are whale sharks endangered?

Yes. They are listed as Endangered, with the population down by about 50% over 75 years, mainly from fishing, bycatch and ship collisions.

Each Whale Shark has its own pattern of spots and stripes. In Madagascar they are called marokintana, meaning many stars, and one appears on the Philippine 100-peso bill.

They can filter over 6,000 litres of water per hour through sieve-like gill pads.

Their mouths can hold over 300 rows of tiny teeth, and one 12.1 m shark had a mouth 1.55 m across.

They are ovoviviparous: a female caught in 1996 was pregnant with about 300 pups, which are born live at 40 to 60 cm long.

A pregnant female nicknamed Rio Lady travelled 7,772 km in 150 days, from the Yucatan Peninsula towards the Mid-Atlantic Ridge.