There is an extraordinary story in The Times today of a notorious pair of killer whales (orcas) which killed 17 sharks in one day. You might know that orcas have a taste for liver. They only ate the livers of the 17 sharks. Just gaping holes in the side of each shark. And the event took place off the coast of South Africa.
The experts in the area know that these orcas are about because their dorsal fin flops over. They are unmistakable. And they are unmistakably intelligent and efficient in their hunting methods.
One website claims that in an IQ test orcas had an intelligence equivalent to that of 15-year-old humans! I’m not sure that that is true but what is true is that they are intelligent and that they have the second-biggest brains among all ocean mammals. Their brain weighs as much as fifteen pounds.
There are not just smart but scary smart. And it is extraordinary to me that they can simply eat liver and leave the rest. This must mean that there is no shortage of food for them. And this in turn means that they are highly efficient in hunting and killing and of course that there is a sufficient supply of sharks.
Unsurprisingly, sharks are scared of killer whales. When an orca is about sharks disappear and apparently sometimes, they don’t return to that spot for 12 months. And it happens even if the orcas are passing through.
Orcas can kill great white sharks. The carcasses of five great white sharks were washed ashore in South Africa on another occasion. Their sizes ranged from 2.7 m to around 4.9 m.
On this occasion, it is said that the killing efficiency of this pair of adult male orcas which have been named Port and Starboard has overturned the marine hierarchy in their hunting grounds.
They arrived in False Bay, in Western Cape province in 2015. At that time, sightings of the world’s most famous great white sharks dried up completely and there remains washed up on beaches. I believe that this is a reference to what I’ve mentioned above.
Researchers from the Marine Dynamics Academy said the orcas’ most recent hunt off Pearly Beach, which is 115 miles along the coast from Cape Town, was the deadliest recorded so far.
Killer whales normally work in groups or pairs. They grip their prey’s pectoral fins in their jaws. They then flip the shark over and rip it open.
All the shark victims were females and all had a clean tear between their pectoral fins. These are the side fins at the front. The livers were absent in each case. All the other organs were left intact.
The experts believe that more shark carcasses will turn up.
Orcas are apex predators. They are also known to prey on baleen whales and have been recorded attempting to prey on sperm whales.
Why do orcas only eat the livers of sharks? It can only be for one two reasons: firstly, they are tasty and secondly, they are nutritious. And as mentioned there are enough sharks around to not bother about eating any other part of their prey.
It might be reasonable to assume that once they have reduced the population of sharks where they are hunting, they may then eat other parts of the body.
Below are some articles on marine wildlife.
