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"Some aspects of white shark metabolism, as well as other aspects of its overall biochemistry, might be more similar to that of a mammal than to that of a bony fish," says Michael Stanhope. (Credit: Ken Bondy/Flickr)

endangered species

Sharks are more like us than you think

When scientists compared great white shark genes with those of humans and zebrafish, they found that the shark genes were surprisingly similar to humans’.

The genetic code of the world’s oldest ocean predator is so effective, scientists say, it has barely changed since before the time when dinosaurs roamed the earth.

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A new study in BMC Genomics lays the foundation for genomic exploration of sharks and vastly expands genetic tools for their conservation, says Michael Stanhope, professor of evolutionary genomics at Cornell University.

“We were very surprised to find, that for many categories of proteins, sharks share more similarities with humans than zebrafish,” he says. “Although sharks and bony fishes are not closely related, they are nonetheless both fish … while mammals have very different anatomies and physiologies.

“Nevertheless, our findings open the possibility that some aspects of white shark metabolism, as well as other aspects of its overall biochemistry, might be more similar to that of a mammal than to that of a bony fish.”

The study launched when Stanhope and Mahmood Shivji, professor at Nova Southeastern University received a Save Our Seas Foundation grant and a rare gift of a great white shark heart. The heart had been autopsied from an illegally fished shark, confiscated by government authorities and donated to the project.

Of particular interest was that white shark had a closer match to humans for proteins involved in metabolism.

“Sharks have many fascinating characteristics,” Stanhope says. “Some give live birth to fully formed young, while some lay eggs. In some species, the embryos eat the remaining eggs or even other embryos while still developing in the uterus.

“Some can dive very deep, others cannot. Some stay local; others migrate across the entire ocean basins. White sharks dive deep, migrate very long distances and give live birth. We will use what we’ve learned in this species in a broader comparative study of genes involved in these diverse behaviors.”

Because sharks are apex predators, their decreasing number threatens the stability of marine ecosystems, on which millions of people rely for food.

The new study also increased the number of genetic markers scientists can use to study the population biology of great white and related sharks by a thousandfold.

 Source: Cornell University

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