Question: How smart are sharks? —Amanda S., New York City

Answer: It depends on how you define smart, but in general sharks have a bigger brain, and are capable of more complex behaviors, than most people expect!

As the cliché (often wrongly attributed to Einstein) goes, “If you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.” Sharks aren’t especially likely to compose a symphony or solve a complex mathematical proof, but they’re also not mindless killing machines.

“I’ve actually never liked the word ‘smart,’ because it’s a very difficult thing to measure,” Dr. Kara Yopak, an assistant professor at UNC Wilmington who studies shark brains, tells me. “What we can say is that sharks have surprisingly large brains relative to their body sizes, are capable of some remarkably complex behaviors and exhibit impressive learning capabilities.”

Let’s review some of the biological and behavioral evidence, starting with brain size.

Basically, absolute brain size doesn’t matter as much as relative brain size: You’d expect a blue whale to have a bigger brain than a mouse because a blue whale is much, much bigger than a mouse.

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But as Yopak’s research has shown, sharks have a bigger relative brain size compared to their body size than many animals. The manta ray, a shark relative, actually has the biggest brain of any fish, so it’s perhaps not surprising that manta rays have complex social relationships and can even recognize themselves in mirrors. What parts of the brain are relatively large or small depends on where a given shark species lives and their typical behaviors, so much so that experts like Yopak can look at a shark’s brain and determine where it lives and what it eats, which is a little beyond the scope of your question, but pretty neat and worth mentioning here.

Sharks also have surprisingly intricate and complex behaviors for fish. Not only are they capable of long-distance repeated migrations and complicated hunting behaviors, but they have complicated social interactions, hanging out with certain other individuals more than you’d expect just due to random chance. They even exhibit social learning, which means they’re able to learn a new behavior from watching another member of their species do it. And there’s evidence that sharks are capable of problem solving, and can remember the solutions to puzzles for almost a year!

How smart are sharks? Well, it depends on how you measure smarts, but they have bigger brains than we’d expect, and they have all kinds of behaviors that we associate with intelligence!

Ask a Marine Biologist is a monthly column where Dr. David Shiffman answers your questions about the underwater world. Topics are chosen from reader-submitted queries as well as data from common internet searches. If you have a question you’d like answered in a future Ask a Marine Biologist column, or if you have a question about the answer given in this column, email Shiffman at [email protected] with subject line “Ask a marine biologist."

Dr. David Shiffman is a marine conservation biologist specializing in the ecology and conservation of sharks. An award-winning public science educator, David has spoken to thousands of people around the world about marine biology and conservation and has bylines with the Washington Post, Scientific American, New Scientist, Gizmodo and more. Follow him on Twitter, Facebook and Instagram, where he’s always happy to answer any questions about sharks.

The views expressed in this article are those of David Shiffman, and not necessarily the views of Sport Diver or Scuba Diving magazines.