The most common reef sharks in Tuvalu are grey reef sharks and blacktip reef sharks. Blacktip reef sharks have a neat black tip on each fin, like they have been dipped in ink. They are often seen in the shallow waters of the lagoon, where their fins sometimes poke above the surface. They are curious about divers and snorkellers but are not aggressive.
Reef sharks are important for the health of the reef. By eating certain fish, they stop any one species from getting too common and eating all the coral. Scientists call this 'keeping the balance' — the reef would actually become less healthy without its sharks. They are like the patrol officer of the underwater neighbourhood.
Sharks have been swimming in the world's oceans for more than 400 million years — long before dinosaurs appeared. They have an amazing ability called electroreception, which means they can detect tiny electrical signals made by the muscles of other fish. This helps them hunt even in murky water or complete darkness.