Sharks

Despite their fearsome reputation as ruthless predators, sharks are much more likely to be killed by humans than the other way round.
© National Geographic Stock/ Paul Nicklen / WWF © naturepl.com/Doug Perrine / WWF © Wildlife Pictures/Jêrome Mallefet / WWF-Canon © Brent Stirton / Getty Images © naturepl.com/Jeff Rotman / WWF © naturepl.com/Alan James / WWF © Cat Holloway / WWF-Canon © Jürgen Freund / WWF-Canon © Brian J. Skerry / National Geographic Stock / WWF © Jason Rubens / WWF-Canon © naturepl.com/Jeff Rotman / WWF © Jürgen Freund / WWF-Canon © Michel Gunther / WWF-Canon

Key Facts

  • Common Name

    shark

  • Scientific Name

    Class: Elasmobranchii (cartilaginous fish); Superorder: Selachimorpha

  • Status

    Some species are critically endangered; CITES appendix I & II

  • How many?

    There are 440 species of shark

Sleek predators of the sea

The first sharks lived around 400 million years ago, with most sharks developing during the Cretaceous period - that's 64 million years ago.
There are over 500 species, and new ones are still being discovered - sharks can be found in every ocean of the world, with some species also found in rivers. Very few sharks are known to have attacked humans but 3 of them are the great white shark, the tiger shark and the bull shark.

Physical description

Sharks vary greatly in size and habit. Whale sharks are the largest of all fish and can grow up to 12m long and weigh up to 12,000kg. The smallest shark is thought to be the dwarf lantern shark, which is just 17cm long.

Shark food

Sharks are efficient predators. They have a highly developed sense of smell, hearing and sight. They can scent their prey in the water from a great distance. Their sensitive eyes can see clearly even in the dim light of the ocean depths.

Most sharks are carnivorous and eat fish, including other sharks. Large species may eat seals, turtles and penguins. However, ome sharks, like the whale shark  and the basking shark feed on plankton

Baby sharks

Most fish lay eggs in the water which are then fertilised by the male. But shark eggs are fertilized inside the female's body. In most species, the eggs hatch inside the female and the babies (called pups) are born alive. Some kinds of sharks, like the catshark do lay eggs, ejecting them in flattened cases known as Mermaid's Purses.

Some sharks that give birth to live babies have as few as 2-3 pups at one time. Others have around 12 and some as many as 70-80. A new born shark is able to swim as soon as it is born and is immediately left to fend for itself by the mother.

What are the main threats?

Because sharks cannot breed fast like other fish, it means that their numbers can be easily be reduced by overfishing.

Demand for shark fins

The growing trade in shark fins - often used to make an expensive Asian soup - has become a serious threat to many shark species. Sharks are caught, the fins are cut off and the rest of the shark is thrown back into the sea.

Bycatch

Other sharks die in fishing nets set for other fish (bycatch) and shark meat is popular in many parts of the world. All this means that some species of sharks are now endangered and critically endangered.

Habitat loss

The increase of development, pollution and over-fishing have led to the loss of important marine habitats that support shark populations.

Thresher shark (Alopias vulpinus) caught in gill net, Gulf of California, Mexico. / ©: Brian J. Skerry / National Geographic Stock / WWF
Thresher shark (Alopias vulpinus) caught in gill net, Gulf of California, Mexico.
© Brian J. Skerry / National Geographic Stock / WWF

What is WWF doing?

WWF is among other conservation organisations leading the fight to save the world's sharks. It is seeking a ban on certain kinds of fishing nets and working to regulate the trade in shark fins. It supports trade controls through TRAFFIC.

WWF directly works to address the problem of overfishing throughout the world's oceans through its Smart Fishing initiative.

Specific projects aim to raise awareness of the plight of sharks, improve the management of marine protected areas and develop ecotourism projects which support sharks in their natural environment. A 2011 study by the Australian Institute of Marine Science found that a single reef shark in Palau generates nearly $2 million for the tourist industry over its lifetime.

Examples of WWF projects that specifically or indirectly target shark conservation:

Logging details from Whale shark satellite tag, Philippines
. / ©: Jürgen Freund / WWF-Canon
WWF Philippines Donsol Research Coordinator Elson Aca writing down details of a whale shark (Rhincodon typus) satellite tag into his slate.
© Jürgen Freund / WWF-Canon
Traffic logo / ©: Traffic
Traffic logo
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WWF Shark Initiative

The WWF Hong Kong Shark Initiative works to address the threat posed by the increasing consumption of shark fin soup in Hong Kong.

How you can help

Make a donation

Did you know?

    • Sharks have up to 5 rows of teeth which are replaced as they wear out. A shark may grow and lose more than 30,000 teeth in its lifetime.
    • The fastest shark is the mako shark which has been known to reach 32kph or even faster. It can also leap 6m above the surface of the water.
    • Most oceanic sharks must keep swimming forwards to force seawater through their open mouths and over their gills to breathe - otherwise they would suffocate.

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