The Ocean’s Most Misunderstood Genius

While sharks are often thought to be mindless predators driven solely by their instinct and voracious hunger, science suggests they’re actually pretty clever and good learners. The more researchers study these ancient animals, the more they discover capabilities that blur the line between cold-blooded killer and surprisingly sophisticated creature — one that can do math, appreciate music, and even maintain long-term friendships.

Sharks can distinguish between subtly different sounds, as well as different abstract patterns and colorful geometric shapes. In one famous experiment, young grey bamboo sharks were shown to remember information about shapes and optical illusions for almost a year. They can also do basic mathematics, telling the difference between quantities such as three and five, and four and seven — though not quantities as close as four and five. For an animal that most people picture purely as a teeth-and-instinct machine, that’s a remarkable cognitive toolkit.

Jazz Fans of the Deep

Perhaps the most delightfully unexpected shark discovery involves music — specifically jazz. As far as Port Jackson sharks are concerned, it don’t mean a thing if it ain’t got that swing. Examples of this Australia-favouring, bottom-dwelling species were set a challenge: swim over to a certain spot of their tank when music played, and they’d be fed a reward. The study, carried out by researchers at Sydney’s Macquarie University, showed the sharks favoured the feeding spot when jazz was being played but were not able to make the same association for classical music.

Researcher Culum Brown noted, “It was obvious that the sharks knew that they had to do something when the classical music was played, but they couldn’t figure out that they had to go to a different location.” The finding suggests sharks can distinguish between complex soundscapes — a skill that speaks to a far more nuanced sensory world than their fearsome reputation implies.

Belly Buttons, Cannibalism, and Other Surprises

While some sharks lay eggs, many — including bull sharks and hammerheads — carry their young in their uterus and feed them through an umbilical cord, just like humans. This is why, for a few weeks or months after birth, these pups have belly buttons until the scar from the umbilical cord heals. It’s one of several ways sharks are more biologically similar to us than most people realize.

On the darker end of the reproductive spectrum, sand tiger sharks take sibling rivalry to an extreme. Sand tiger shark babies are thrown into a fight for survival right from the beginning — while still inside their mother. Female sand tiger sharks have two uteruses, and as many as five young grow in each. The embryos feed on their siblings until there is only one left — a process known as intrauterine cannibalism, or adelphophagy, which means “eating one’s brother.”

Social Lives and Skin That Built Violins

Sharks aren’t the lone hunters they’re often depicted to be. Grey reef sharks like to hang out with the same clique of friends for as long as four years, splitting up into smaller groups, going their own ways, and then regrouping throughout the seasons. Great whites may even have best friends — two great white sharks named Simon and Jekyll were seen to travel together for 6,000 km (3,730 miles) without ever separating.

Shark skin is a wonder material. In 18th-century Italy, craftsmen used it to smooth the delicate edges of priceless Stradivarius violins, and in Victorian Britain, it became a favoured accessory for cabinet makers who called it “shagreen.” Instead of scales, shark skin is studded with numerous tiny “teeth” — called denticles — which are flattened by the creature’s forward movement through water, reducing aerodynamic drag. That same hydrodynamic engineering has inspired modern swimsuit and aircraft design. The more science looks at sharks, the more it finds an animal that has been quietly perfecting its craft for hundreds of millions of years — and still has plenty of secrets left to reveal.