Great whites use stored liver oil to power through ocean “road trips”

18 Jul
This is a juvenile great white shark at the Monterey Bay Aquarium. (Credit: Randy Wilder)

This is a juvenile great white shark at the Monterey Bay Aquarium. (Credit: Randy Wilder)

Bears, sea lions and whales rely on their external blubber to power through hibernations and migrations.

For them, a little extra flab is crucial to their survival.

Would a Great white shark be so intimidating if it was a little overweight? Probably not. It may instead get the stigma of a cop eating a doughnut with his mouth open.

But, like other large megafauna, Great whites migrate thousands of miles across the Pacific ocean  without eating much, and their lean physiques have puzzled scientists.

Where is the fat to fuel the trip stored?

A new study by scientists at Stanford University and the Monterey Bay Aquarium found that instead of storing fat externally, Great white’s instead store the fat in their liver, discounting the previous notion that the sharks would periodically dine throughout the voyage.

“We have a glimpse now of how white sharks come in from nutrient-poor areas offshore, feed where elephant seal populations are expanding – much like going to an Outback Steakhouse – and store the energy in their livers so they can move offshore again,” researcher Barbara Block, a professor of marine sciences and a senior fellow at the Stanford Woods Institute for the Environment, said. “It helps us understand how important their near-shore habitats are as fueling stations for their entire life history.”

The study also revealed that the fat, which is converted into oil in the liver, affects the buoyancy of the shark. As the sharks gained body mass, they also gained buoyancy and, over the course of their migration their buoyancy slowly decreased. The energy being used to fuel the trip was oil stored in the liver and not gained from quick meals along the way.

“Sharks face an interesting dilemma,” Sal Jorgensen, a research scientist at the Monterey Bay Aquarium, said. “They carry a huge store of energy in the form of oil in their massive livers, but they also depend on that volume of oil for buoyancy. So, if they draw on those reserves, they become heavier and heavier.”

The authors of the study say that the findings reveal more than just the biology of these creatures. The results show  that the meals they eat near shore before their migration is crucial to their survival. They say conservation efforts should include the coastal “buffets”–not only for sharks but also other sea creatures that rely on high calorie meals for migrations.

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One Response to “Great whites use stored liver oil to power through ocean “road trips””

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  1. Editor’s picks for 2013 | Layman's Terms Media - December 2, 2013

    […] Great whites use stored liver oil to power through ocean “road trips”: Bears, sea lions and whales rely on their external blubber to power through hibernations and migrations. For them, a little extra flab is crucial to their survival.—> Continue reading […]

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