Great White Sharks Are Turning Up Dead Without Their Livers
Serial killer (whales) are on the loose! Three dead liver-less sharks washed up on the shores of South Africa's Western Cape province in a span of four days. One was also missing its heart.
According to a report from Live Science, the bizarre phenomenon prompted scientists to perform necropsies on the three bodies. The animal autopsies revealed that orcas were behind the attacks, although no one actually witnessed the events.
"These observations are unprecedented," white shark biologist Alison Towner wrote on the Marine Dynamics blog. "We don't really know how long the sharks will stay away from the area as a result of predation pressure."
Great white sharks is not the usual prey of killer whales, but it's not totally unheard of specifically in places like southern Australia and San Francisco.
But why the liver? Andrew Nosal, an assistant professor of biological sciences at Saint Katherine College and visiting assistant researcher at Scripps Institution of Oceanography who wasn't involved in the study, pointed out that marine mammals like sea lions often target livers and other internal organs.
Sea lions usually trash leopard sharks around until their prey are "eviscerated" and all their internal organs come spilling out. The predators proceed to eat the different organs, ignoring the rest of the body until it sinks under the water or wash up on the shore like the ones that were recently found in South Africa.
Shark livers are particularly appealing because they are filled with fats, energy and nutrients.
"Bony fishes have a swim bladder that they can fill with gases, and those gases provide buoyancy for the fish," Nosal said. "Sharks do not have a swim bladder. Instead, they have a very large liver."
With their high metabolism and bloated nutrient needs, orcas could likely benefit from the fat provided by snacking on the livers.