The first thing that pops into most people’s minds when they think of sharks is of big dumb fish with pointy teeth that are to be greatly feared. But as someone who spends their days studying these creatures, I know just how wrong that image is. For one, thing the diversity of sharks is astounding. The differences between species can even make it seem like some of these animals are barely related.
My new research, carried out with colleagues in the UK and South Africa, shows that significant differences can even exist between male and female members of the same species. Our study of South African great white sharks revealed that females don’t always make the switch from eating fish as youngsters to eating seals and other marine mammals when they’re older. Instead, our findings suggest that some females may specialise on fish prey and use different habitats to males.
How on Earth did we find this out? We conducted a type of chemical study known as stable isotope analysis on small pieces of muscle that we collected from free-swimming white sharks while on board a cage diving ecotourism boat. This gave us information on what the sharks had been eating and which habitats they had been using for a roughly two-year period – the first time that this analysis has been used on samples from live South African sharks. MORE