Ms Towner, who is based at the shark hotspot of Gansbaai, two hours east of Cape Town, said killer whales had only ever been spotted attacking great whites twice, and never before around South Africa.
She said the whales may have started targeting great whites because their other food sources were disappearing as a result of pollution or climate change.
There are only two predators alive that are bigger than killer whales – the sperm whale and the giant squid.
Continue reading: Great White Shark v Killer Whale: The two deadliest sea titans are now waging war on each other