Sharks are the most fearsome predatory fish of the seas. There are 375 species, living mostly in warm seas.
Sharks have a skeleton made of rubbery cartilage – most other kinds of fish have bony skeletons.
The world’s biggest fish is the whale shark, which can grow to well over 12 m long. Unlike other sharks, the whale shark and the basking shark (at 9 m long) mostly eat plankton and are completely harmless.
A shark’s main weapons are its teeth – they are powerful enough to bite through plate steel.
A shark’s torpedo-shaped body makes it a very fast swimmer.
Sharks put so much strain on their teeth that they always have three or four spare rows of teeth in reserve.
Nurse sharks grow a new set of teeth every 8 days.
Up to 20 people die from recorded shark attacks each year.
The killing machine of the shark world is the great white shark, responsible for most attacks on humans.
Hammerhead sharks can also be dangerous. They have T-shaped heads, with eyes and nostrils at the end of the T.
The super-streamlined blue shark lives in warm seas and is 3.7 m in length. It has very long side fins and eats surface fish like herring and mackerel.