The whale shark is the biggest fish in the world. Most are 5.5 to 10 m long, and the largest measured was 18.8 m. It is a gentle filter feeder that sieves plankton and small fish through pads in its huge mouth. It lives in warm seas worldwide, can live at least 75 years, and is listed as Endangered.
whale sharks quick facts
- The whale shark is the largest fish in the world.
- The longest whale shark measured was 18.8 m (61.7 feet).
- Each whale shark has its own pattern of spots, like a fingerprint.
- One whale shark was carrying about 300 unborn pups.
- Whale sharks have been listed as Endangered since 2016.
What is a whale shark?
The whale shark is the biggest fish in the world. The US Bureau of Ocean Energy Management (BOEM) says it is the largest shark and the largest fish alive today.
Despite its name, a whale shark is not a whale. It is a shark, and sharks are fish. It is called a whale shark because it is as big as some whales, and because it feeds a bit like the great filter-feeding whales.
Whale sharks are gentle giants. BOEM says they are harmless to people. Instead of hunting big prey, they eat some of the tiniest living things in the sea.
| Whale shark at a glance | |
|---|---|
| Usual length | about 5.5 to 10 m (18 to 32 feet) |
| Longest measured | 18.8 m (61.7 feet) |
| Mouth | up to about 1.5 m (5 feet) wide |
| Food | plankton, fish eggs and small fish |
| Where | warm seas around the world |
| Lifespan | at least 75 years, maybe over 100 |
| Status | Endangered |
Name and discovery
The whale shark’s scientific name is Rhincodon typus. The Florida Museum says “Rhincodon” comes from Greek words meaning “rasp” and “tooth”. A rasp is a rough tool for filing.
Scientists first described the whale shark in 1828. The Florida Museum says the first one studied was found in Table Bay, in South Africa.
The biggest fish in the sea
Whale sharks are enormous. Georgia Aquarium says most are about 5.5 to 10 m (18 to 32 feet) long. The largest one ever measured was 18.8 m (61.7 feet) long, longer than a school bus.
They are very heavy too. Animal Diversity Web says a very large whale shark can weigh around 30 tonnes, as much as several elephants.
Whale sharks are tough as well as big. Georgia Aquarium says their skin can be up to 10 cm (4 inches) thick.
Whale sharks are much bigger than hunting sharks such as the great white shark or the tiger shark.
Spots like fingerprints
Whale sharks are covered in pale spots and stripes on a dark grey or bluish background. Georgia Aquarium says every whale shark has its own pattern.
The pattern works like a fingerprint. BOEM says scientists use photos of the spots to tell individual whale sharks apart, so they can recognise the same shark when they see it again, even years later.
A giant mouth
A whale shark has a huge, wide mouth at the very front of its flat head. Georgia Aquarium says it can be about 1.5 m (5 feet) wide, big enough for a child to stand in.
Inside are thousands of tiny teeth. Georgia Aquarium says there are about 300 rows of them in each jaw. But NOAA Fisheries says whale sharks do not use their teeth to eat.
Instead, the Florida Museum says the whale shark has 20 spongy filter pads inside its mouth. They work like a sieve, catching food from the water.
Here is a surprise. Georgia Aquarium says that even though a whale shark is enormous, its throat is only about as wide as a large coin. It could never swallow a person.
What do whale sharks eat?
Whale sharks are filter feeders. Georgia Aquarium and BOEM say they eat tiny plankton, such as krill, copepods and shrimp larvae, as well as fish eggs, coral spawn and small fish like sardines and anchovies.
Their filters can catch food only a few millimetres across, according to the Florida Museum.
A whale shark needs a lot of these tiny meals. The Florida Museum says one estimate is that a whale shark filters about 20 kg (45 pounds) of plankton a day.
The biggest animal of all, the blue whale, also feeds on tiny krill. It is amazing that the largest animals in the sea eat some of the smallest.
How whale sharks feed
BOEM says whale sharks feed in two ways. Sometimes they swim along slowly with their mouths wide open, letting water and food flow in.
At other times, they suck in big gulps of water. The water pushes out through their gills, and the filter pads keep the food inside.
Georgia Aquarium says whale sharks swim at only about 3.7 km/h (2.3 mph) when they feed at the surface, about as fast as a person walking slowly.
Where do whale sharks live?
Whale sharks live in warm seas all around the world. The Florida Museum and BOEM say they are found in tropical and warm waters in every ocean, except the Mediterranean Sea.
They like surface water between about 21 and 30 °C (70 to 86 °F), the Florida Museum says. BOEM says they are mostly seen in the tropics, but have been spotted as far north as Massachusetts in the United States.
NOAA Fisheries says whale sharks gather in the northern Gulf of Mexico in summer and autumn, especially at a spot called Ewing Bank, off the coast of Louisiana.
Although they often feed near the surface, whale sharks can dive very deep. The Florida Museum says they have been recorded diving to at least 1,928 m (6,325 feet).
Long journeys
Whale sharks usually live alone. But BOEM says they sometimes gather in large groups in places where there is lots of food. Smaller fish often swim alongside them, too.
Whale sharks travel long distances, following plankton blooms and times when fish lay their eggs. Animal Diversity Web says one whale shark was tracked swimming 13,000 km over 37 months.
Scientists fix tags to whale sharks to learn where they go. NOAA Fisheries says 42 whale sharks were tagged in the Gulf of Mexico between 2008 and 2014, and some were tracked for up to 366 days.
Whale shark pups
Whale sharks do not lay eggs in the sea. Georgia Aquarium and BOEM say the eggs hatch inside the mother, and she gives birth to live young, called pups.
A mother can carry a lot of babies. The Florida Museum says that in 1995, scientists studied an 11 m (36 foot) female that was carrying about 300 unborn pups.
Georgia Aquarium says newborn pups are about 55 to 64 cm (21 to 25 inches) long, smaller than a child’s arm span.
Whale sharks grow up slowly. The Florida Museum says they are ready to have young of their own when they reach about 9 m (30 feet) long, and Animal Diversity Web says this may take up to 30 years.
How long do whale sharks live?
Whale sharks can live a very long time. NOAA Fisheries says the oldest whale shark studied was about 75 years old, and scientists think they may live more than 100 years.
Whale sharks in aquariums
A few very large aquariums keep whale sharks, so visitors can see these giants up close. NOAA Fisheries says Georgia Aquarium in Atlanta keeps four whale sharks.
Aquariums help scientists learn about how whale sharks eat, grow and behave. This knowledge can help protect whale sharks in the wild.
Whale sharks in danger
Whale sharks are in trouble. Georgia Aquarium and NOAA Fisheries say the IUCN lists them as Endangered. They were moved up from Vulnerable in 2016, because their numbers had fallen.
Georgia Aquarium says the dangers include getting caught in fishing nets, being hit by boats, swallowing plastic and rubbish, and badly managed tourism.
In the past, whale sharks were also caught for food. The Florida Museum says Taiwan caught about 100 a year until 2008, and Cuba banned its small whale shark fishery in 1991.
Whale sharks are now protected by international agreements. Georgia Aquarium says trade in whale sharks has been controlled under the CITES agreement since 2003. They are also protected as a migratory species.
How you can help
You can help whale sharks by using less plastic, so less of it ends up in the sea. If you ever go to see whale sharks, choose a tour that keeps its distance and does not chase or touch them.
How scientists study whale sharks
Studying an animal that roams across whole oceans is not easy. BOEM says scientists photograph the pattern of spots behind each whale shark’s gills and compare it with photos taken before. This lets them recognise the same shark years later.
Satellite tags tell scientists where whale sharks go when nobody can see them. In the NOAA Fisheries study in the Gulf of Mexico, some tags kept sending information for a whole year.
Following the feasts
Whale sharks go where the food is. BOEM says they follow blooms of plankton and the times when fish release their eggs. Georgia Aquarium says they also feed on coral spawn, the clouds of eggs that corals release into the water.
Because these feasts happen at the same places and times each year, whale sharks often turn up in the same spots in the same seasons. That is why people in some places can predict when whale sharks will arrive.
Three things people get wrong
A whale shark is not a whale. It is a shark, which is a kind of fish.
Whale sharks are not dangerous to people. They are gentle filter feeders.
Whale sharks do not use their teeth to eat. They sieve food through filter pads.
Did you know? A whale shark’s throat is only about as wide as a large coin, even though its mouth can be 1.5 m wide.
Try it
Measure 18.8 metres in a playground or park. That is the length of the biggest whale shark ever measured.
Knowledge check
Is a whale shark a whale?
Show answer
No. It is a shark, which is a fish.
What do whale sharks eat?
Show answer
Plankton, fish eggs and small fish, filtered from the water.
Frequently asked questions
How big is a whale shark?
Most whale sharks are 5.5 to 10 m long. The largest ever measured was 18.8 m (61.7 feet), longer than a school bus.
Is a whale shark a whale or a shark?
A whale shark is a shark, which is a kind of fish. It is named for its huge size and its whale-like way of feeding.
What do whale sharks eat?
Whale sharks are filter feeders. They eat plankton such as krill and copepods, fish eggs, coral spawn and small fish like sardines.
Are whale sharks dangerous?
No. Whale sharks are gentle and harmless to people. Their throat is only about as wide as a large coin.
Where do whale sharks live?
Whale sharks live in warm, tropical seas around the world, except the Mediterranean. They like water between about 21 and 30 °C.
Are whale sharks endangered?
Yes. The IUCN has listed whale sharks as Endangered since 2016. Threats include fishing nets, boat strikes, plastic and badly managed tourism.
Sources
- Georgia Aquarium: whale shark — size, skin, mouth, teeth, spots, diet, feeding speed, babies, status and threats
- Florida Museum of Natural History: whale shark — name, discovery, filter pads, food, range, depth, the 1995 pregnant female, maturity and fisheries
- Animal Diversity Web, University of Michigan: whale shark — weight, filtering, travel, maturity and lifespan
- US Bureau of Ocean Energy Management: whale shark — largest fish, diet, how it feeds, range, behaviour and identifying spots
- NOAA Fisheries: whale shark movements in the Gulf of Mexico — tagging study, Ewing Bank, teeth, age, status and aquariums
