Sharks attack humans when they mistake swimmers for seals, footage shows

Sharks attack swimmers because they mistake them for seals, a researcher has suggested.

Sensory biologist Dr Laura Ryan investigated great white shark bites to see whether incidents such as the death of Simon Nellis near Sydney may have been a case of mistaken identity.

Dr Ryan's researched showed that the predators lack colour vision, meaning they cannot see in fine details.

This footage, from the Why Sharks Attack BBC documentary, demonstrates how great white sharks might see humans and seals - showing that swimmers and surfers look very similar to seals, supporting a mistaken identity theory.