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Following a fatal attack off New South Wales, sharks are once again in the spotlight. As tragic as these events are, shark attacks are so rare, scientists aren’t sure why humans are bitten at all.

Sharks are found in oceans all around the world – some live near the coast, others in deeper water. Some can even live in freshwater. There are more than 400 species, ranging in size from 17 centimetres to more than 12 metres. Many species are apex predators, and play an important role in marine ecosystems by managing fish populations.

While shark attacks on humans can cause serious injury and even death, they are extremely rare. In Australia there have only been around 50 fatalities in the last 50 years. In 2012, there were only 14 unprovoked attacks. Given that Australians make a total of around 100 million trips to the beach each year, the chances of being bitten by a shark are extremely low.

Because attacks are so rare, marine scientists still aren’t exactly sure why sharks attack in the first place. Some species are more likely to attack than others. Three species – the tiger, white and bull shark – are responsible for most unprovoked attacks on humans. Theories explaining why sharks attack include mistaking humans for prey species such as seals or fish, defending their territory against perceived threats, or simply curiosity.

CSIRO captures, tags, and releases some sharks species, including white and tiger sharks. The tags allow scientists to track the sharks’ movements, and will hopefully lead to a better understanding of their behaviour and interactions with their environment.

In Australia white sharks and a number of other threatened shark species are protected by law. They may be scary, but sharks are an important part of marine food chain – and losing them could have serious consequences to the ecosystem.