Marine mammals prey on livers for buoyancy

In recent months, four bodies of great white sharks have washed up on the western shores of South Africa. Each shark’s liver had been “surgically” removed, along with the hearts in two of the cases.

Orca whale
By Minette Layne from Seattle, Washington, USA – Single breaching orca (cropped), CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=3351306

The culprit for these deaths has been determined to be orca whales, also known to live in that region where the Indian and Atlantic oceans meet. Orcas don’t often prey upon great whites, althought it isn’t unheard of. More frequently, they are known to consume the livers of the broadnose sevengill shark off the coast of California.

Also off California, sea lions hunt leopard sharks and also consume their livers.

The livers of sharks are very large, and contain fats which give them buoyancy; this is necessary as sharks lack the gas-filled swim bladder of bony fish. Eating these livers may help the predator’s buoyancy, as well as providing a nutrient-rich meal.

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