'The most impressive strategy is the 'karate chop'," said expert Dr Ingrid Visser, 43, who has studied orca behaviour for 17 years.
'The orca will use its tail to drive the shark to the surface. They don't even touch it. Using an up-thrust of its tail it creates a vortex which pushes the shark up on the current they create with their movements.
'Once the shark is at the surface, the killer whale pivots and lifts its tail out of the water and comes down on top of it like a karate chop.'
With the shark dazed, the orca grasps the dazed shark and turns it upside down - giving a mind-boggling impression that the killer whale understands shark biology. When sharks are quickly flipped upside down, they enter paralysed state known as 'tonic immobility' - making for an easy meal.
'It's not that the orca understands the physiology of the shark,' said Dr Visser, from Tutukaka, North Island, New Zealand.. 'But it does demonstrate that they understand the behavioural consequences of what will happen if they take a certain action.'
Read more: http://www.dailymail.co.uk/sciencetech/article-1231454/Killer-whales-Death-karate-chop-deadly-tactic-used-orcas-sharks.html#ixzz2IZ4qOxeR
Dr. Ingrid Visser captured the moment a New Zealand orca delivered a 'karate chop' blow to a shark, and describes this impressive hunting strategy (article: 2009)