Basking shark facts for kids
Quick facts for kids Basking Shark |
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| The size of basking sharks at various stages of growth and maturity with a human for scale | |
| Conservation status | |
Scientific classification  |
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| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Order: | Lamniformes |
| Family: | Cetorhinidae |
| Genus: | Cetorhinus Blainville, 1816 |
| Species: |
C. maximus
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| Binomial name | |
| Cetorhinus maximus (Gunnerus, 1765)
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| Range of the basking shark | |
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| Synonyms | |
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Squalus maximus Gunnerus, 1765
Selache maxima (Gunnerus, 1765) Halsydrus pontoppidiani* Neill, 1809 Squalus gunnerianus Blainville, 1810 Squalus homianus Blainville, 1810 Squalus pelegrinus Blainville, 1810 Tetraoras angiova* Rafinesque, 1810 Tetroras angiova* Rafinesque, 1810 Squalis gunneri* Blainville, 1816 Squalis shavianus* Blainville, 1816 Scoliophis atlanticus* Anonymous, 1817 Squalus isodus Macri, 1819 Squalus rostratus Macri, 1819 Squalus elephas Lesueur, 1822 Squalus rashleighanus Couch, 1838 Squalus rhinoceros* DeKay, 1842 Squalus cetaceus Gronow, 1854 Polyprosopus macer Couch, 1862 Cetorhinus blainvillei Capello, 1869 Hanovera aurata van Beneden, 1871 Selachus pennantii Cornish, 1885 Tetroras maccoyi Barrett, 1933 Cetorhinus maximus infanuncula Deinse & Adriani, 1953 Cetorhinus normani Siccardi, 1961 ---- * ambiguous synonym |
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The basking shark (Cetorhinus maximus) is an amazing ocean giant. It is the second-largest living shark and fish in the world. Only the whale shark is bigger. Basking sharks eat tiny ocean creatures called plankton. They share this diet with whale sharks and megamouth sharks.
These gentle giants usually grow to about 7.9 meters (26 feet) long. Some very large ones have been seen over 10 meters (33 feet) long. They are typically greyish-brown with spotted skin. Their mouth is white inside. The tail fin is strong and shaped like a crescent moon. People sometimes call them bone sharks or sunfish.
Basking sharks live in all temperate oceans around the world. They are migratory animals, meaning they travel long distances. Their name comes from how they feed. They swim slowly near the surface, looking like they are "basking" in the sun. They have a huge mouth and special gill rakers to catch plankton. Their snout is cone-shaped. The gill slits go all around their head. These dark, bristly gill rakers filter tiny food from the water. Their teeth are very small, about 100 in each row. They are curved backward and are the same on both jaws. Basking sharks have a very small brain for their size. This shows their calm and peaceful way of life.
These sharks can spend winters in deep waters, sometimes over 900 meters (3,000 feet) down. They can be found alone or in small groups. Even though they are huge, basking sharks are not aggressive. They are completely harmless to humans.
For a long time, people fished basking sharks. They were used for food, shark liver oil, and animal feed. Sadly, too much fishing has made their numbers drop. Now, many basking shark populations need protection.
Contents
Discovering the Basking Shark
The basking shark is the only living member of its family, Cetorhinidae. This family belongs to a group of sharks called mackerel sharks. Johan Ernst Gunnerus first described this species in 1765. He found a specimen in Norway. The name Cetorhinus comes from Greek words. Ketos means "marine monster" or "whale." Rhine is an old word for "shark." The name maximus is Latin for "greatest."
Ancient Relatives
The oldest known relatives of the basking shark lived a very long time ago. These ancient sharks, called Keasius, lived during the middle Eocene epoch. This was about 40 to 50 million years ago. Modern basking sharks, like the ones we see today, appeared later. They showed up during the Late Miocene epoch, around 5 to 11 million years ago.
Where Do Basking Sharks Live?
Basking sharks live in cool to warm waters all over the world. They prefer temperatures between 8 and 14.5 degrees Celsius (46 to 58 degrees Fahrenheit). They are often found near coastlines and sometimes enter brackish waters. This means water that is a mix of fresh and salt water. They can swim from the surface down to at least 910 meters (3,000 feet) deep.
These sharks follow where the plankton is densest. This is why you often see them feeding near the surface. They travel with the seasons, moving to different areas to find food. Scientists have even confirmed them crossing the much warmer waters at the equator.
How Do Basking Sharks Look?
Basking sharks are truly enormous. They usually measure between 7 and 8.5 meters (23-28 feet) long. Some individuals can grow even larger, up to 9 to 11 meters (30-36 feet). An average adult weighs about 4.65 metric tons (10,250 pounds). The largest recorded specimen was 12.27 meters (40 feet) long. It was caught in Canada in 1851. Its weight was estimated at 16 metric tons (35,000 pounds). They are the second-largest fish species alive today, after the whale shark.
Basking sharks have a body shape typical of many sharks. Sometimes, people mistake them for great white sharks. However, it's easy to tell them apart. Basking sharks have a huge mouth, up to 1 meter (3 feet) wide. Their gill slits are very long and almost wrap around their head. They also have much smaller eyes. Great white sharks have large, sharp teeth. Basking shark teeth are tiny, only 5-6 millimeters (0.2 inches) long, and hooked. Only a few rows of their teeth are used. Great white sharks are active hunters. Basking sharks are peaceful filter feeders.
Other special features include a strong tail base and a crescent-shaped tail fin. Their skin feels rough because it's covered in tiny scales. It also has a layer of mucus. Younger sharks have a more pointed snout. In very large sharks, the dorsal fin might flop over when they are at the surface. Their color varies, usually dark brown to black or blue on top. Their belly is a dull white. These sharks often have scars. These might come from encounters with lampreys or cookiecutter sharks. The basking shark's liver is huge. It can be up to 25% of its body weight. This liver helps them float and stores energy for a long time.
Amazing Basking Shark Behaviors
Basking sharks are active all year long. They do not hibernate. In winter, they often swim to deeper parts of the ocean. They can go down to 900 meters (3,000 feet). They make vertical movements, going up and down. This helps them find tiny zooplankton to eat during the colder months.
Why They Jump
These sharks are slow swimmers, moving at about 2 knots (3.7 km/h or 2.3 mph). They usually don't try to avoid boats. They are not attracted to bait. Despite their large size, basking sharks can breach. This means they can jump completely out of the water! Scientists think they might do this to shake off parasites. Or it could be a way to show off their size and strength to other sharks.
Long Journeys
Scientists use satellite tags to track basking sharks. These tags showed that sharks travel thousands of kilometers. They move during summer and winter. They are always looking for the best patches of zooplankton. These rich food areas are often found along ocean fronts.
A study in 2009 tagged 25 sharks near Cape Cod, Massachusetts. It showed that some sharks travel south in winter. They stayed at depths between 200 and 1000 meters (650-3,300 feet) for weeks. Some even crossed the equator to reach Brazil. One shark spent a month near the mouth of the Amazon River. These long trips might be important for their reproduction.
In June 2015, a large basking shark was accidentally caught. It was 6 meters (20 feet) long and weighed 3,500 kilograms (7,716 pounds). This happened in Australia. It was the first one caught there since the 1930s. The shark was given to the Victoria Museum for research. This was a great choice instead of selling its fins.
Friends and Foes
Basking sharks are usually solitary. But in summer, they gather in areas with lots of zooplankton. Here, they show social behaviors. They can form groups of sharks of the same sex. These groups are usually small, about three or four sharks. Sometimes, up to 100 individuals have been seen together. Small groups have been observed swimming in circles, nose to tail. This behavior might be part of their courtship.
Basking sharks have very few natural predators. Killer whales have been seen eating basking sharks. This has happened off California and New Zealand. Lampreys often attach to them. However, lampreys probably cannot bite through the shark's thick skin.
Eating Habits
The basking shark is a filter feeder. It swims forward with its mouth open. This filters zooplankton, tiny fish, and other small creatures from the water. It uses its special gill rakers for this. A 5-meter (16-foot) basking shark can filter up to 500 metric tons (132,000 gallons) of water per hour. It swims at about 0.85 meters per second (1.9 mph).
Basking sharks are picky eaters. They don't just eat any zooplankton. They prefer areas with lots of tiny crustaceans called calanoid copepods. These areas can have 1,700 copepods per cubic meter of water. They also eat other types of copepods. Unlike the megamouth shark and whale shark, basking sharks rely only on swimming to push water through their gills. The other two can actively suck or pump water.
Basking Shark Life Cycle
Basking sharks are ovoviviparous. This means their babies grow inside the mother. They get food from a yolk sac, not a placenta. Their tiny teeth might help them eat unfertilized eggs inside the mother. Only the right ovary in females seems to work. Scientists are still trying to understand why.
The gestation period is very long, possibly two to three years. A small number of fully developed young are born. They are usually 1.5 to 2 meters (5-6.5 feet) long at birth. Only one pregnant female has ever been caught. She was carrying six unborn babies. Mating likely happens in early summer. Birthing probably occurs in late summer. Females move to shallow waters for this.
Basking sharks become mature between six and 13 years old. They are usually 4.6 to 6 meters (15-20 feet) long then. They are thought to breed every two to four years. The exact lifespan of a basking shark is unknown. Experts believe they can live for about 50 years.
Protecting Basking Sharks
Basking sharks face many threats. Besides direct fishing, they are often caught by accident in fishing nets. This is called bycatch. In New Zealand, basking sharks used to be common. But after many were caught as bycatch in the 1990s and 2000s, sightings became very rare. Now, there are plans to help protect them. In June 2018, New Zealand classified the basking shark as "Threatened - Nationally Vulnerable."
The population in the eastern North Pacific Ocean is also a concern. The U.S. government is worried about their numbers. However, there isn't enough information yet to list them under the Endangered Species Act. The IUCN Red List officially lists the basking shark as an endangered species. This means they are at high risk of disappearing. In 2005, a postage stamp was issued in Guernsey to raise awareness.
Basking Sharks and People
Historically, basking sharks were important for fisheries. They were easy to catch because they swim slowly and are calm. Their flesh was used for food and animal feed. Their skin was used for leather. Their large liver was valued for its oil. Today, they are mainly fished for their fins. These fins are used in certain dishes. Other parts, like cartilage, were used for other purposes.
Because their numbers dropped so quickly, basking sharks are now protected. This protection is in many territorial waters. Trade in their products is also restricted by CITES. They are fully protected in the United Kingdom. They are also protected in the Atlantic and Mexican Gulf regions of the United States. Since 2008, it has been illegal to fish for them in European Union waters. If accidentally caught, they must be released. Norway and New Zealand offer partial protection. Targeted fishing is illegal, but accidental bycatch can sometimes be used.
Once, basking sharks were seen as a problem along the Canadian Pacific coast. From 1945 to 1970, there was a government program to reduce their numbers. Since 1994, sightings became rare. In 2008, efforts began to find out if any sharks still lived there. They also wanted to monitor their recovery. One shark was spotted in June 2024 near Wallace Island Marine Provincial Park.
Basking sharks are tolerant of boats and divers. They might even swim in circles around divers. This makes them a big attraction for dive tourism. It helps people appreciate these gentle giants.
Images for kids
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Head of a basking shark
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A basking shark filter feeding
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Basking shark filter feeding at Dursey Sound
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The "wonderful fish" described in Harper's Weekly on 24 October 1868, was likely the remains of a basking shark.
See also
In Spanish: Tiburón peregrino para niños
- List of prehistoric cartilaginous fish
- List of threatened sharks
- Shark liver oil
