Shark Facts

Sharks have patrolled Earth's oceans for roughly 450 million years — predating trees, the first land vertebrates, and most major extinction events. More than 500 species exist today, ranging from the 17-centimetre dwarf lanternshark to the 12-metre whale shark, the largest fish in the ocean. Despite the outsized cultural fear they inspire, sharks kill fewer than ten people globally per year on average, while humans kill approximately 100 million sharks annually through fishing, finning, and bycatch.

Their sensory systems are extraordinary. The ampullae of Lorenzini — jelly-filled pores concentrated around the snout — detect the bioelectric fields generated by the muscle contractions of other animals, allowing sharks to locate prey buried under sand or hidden in murky water. Great whites can detect a single drop of blood diluted in 100 litres of water, and their lateral line system senses pressure disturbances from prey movements metres away. Their teeth are not anchored in bone but sit in rows of soft tissue; a shark may cycle through 30,000 or more teeth across its lifetime.

Shark reproduction varies dramatically across species. Some lay eggs in leathery cases called mermaids' purses; others give birth to live young — and in a few species, the first embryo to develop will consume its siblings in the womb, a practice called intrauterine cannibalism. Greenland sharks grow less than 1 centimetre per year and may live for over 400 years, making them the longest-lived vertebrates currently known to science. Sexual maturity in that species arrives at around 150 years of age.