If you’re afraid of sharks, well, this blog should convince you it’s actually orcas you should avoid. Orcas are among the most savage killers in the ocean, wrecking tiger sharks, seals, beaked whales—and probably one of the most infamous apex predators out there, the great white shark.
Orcas have only been spotted attacking great white sharks a handful of times. But this past week, two mangled great white carcasses washed ashore in the town of Gansbaai on the South African coast. And the corpses definitely showed signs of being leftover orca lunch.
“This is the first confirmed account of an orca predation on a white shark from South Africa,” Marine Biologist Alison Kock from South African National Parks told Gizmodo in an email. “It’s mind blowing to think that a white shark of that size (almost 5m) was a target.”
Another South African marine biologist who organized the autopsy, Alison Towner, told Gizmodo that she could only think of a few other times killer whales preyed on great whites. Boaters filmed a pod of orcas attacking great whites in California in 1997.
A few shark carcasses have turned up in the area around the Gansbaai beaches since 2012—dead great white sharks washing ashore is a rare event itself. But on the morning of May 3rd, someone spotted a 16-foot, 2500-pound dead behemoth. That’s around the same length and half the weight of a full-size Mercedes-Benz.
A massive shark autopsy effort followed. “It is no easy task to manoeuvre such a huge fish from a remote beach to an adequate site for autopsy,” Towner told Gizmodo. “This required a military vehicle and land rover along with lots of manpower and team work.” The autopsy on the largest shark took six hours and blunted twenty knives, she said.
But then another smaller, liverless (and heartless) great white shark carcass washed up on May 4th. And another washed up just yesterday, with matching injuries.
According to the Marine Dynamics shark cage diving company’s blog, a shark missing its liver is a likely sign that an orca had enjoyed it, possibly with some fava beans and a nice chianti, though those details aren’t confirmed. Nor did the researchers confirm how many orcas attacked the shark. As for why the hungry whales focused on the liver, Towner pointed out that shark liver contains lots of the nutrient squalene.
“It seems likely that orcas are again the cause of death but we will confirm after the autopsy,” wrote Towner in the Marine Dynamics blog. “Obviously this is a very sad time for us all, nature can be so cruel and the dexterity these enormous animals are capable of is mind blowing, almost surgical precision as they remove the squalene rich liver of the white sharks and dump their carcass.”
Even at the top of the food chain, nobody’s safe.
source: gizmodo.com by Ryan F. Mandelbaum