Good at maths and into jazz: Nine extraordinary things you probably didn't know about sharks

Humans have more in common with these elite ocean predators than often thought. A little Miles Davis anyone?

Sharks are among the Earth's original vertebrate predators.

They (or their close ancestors) survived all five of Earth's major mass extinctions – including the largest and most devastating, the Permian-Triassic extinction, or the "Great Dying". This cataclysmic climate event killed the majority of life on Earth, including around 90% of marine life. 

But sharks lived on. Today they are found in just about every bit of the ocean – and after hundreds of millions of years of evolution, they have developed some surprising traits along the way.

Here are nine extraordinary facts about sharks.

1. Sharks can do maths

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. They can distinguish between subtly different sounds, as well as different abstract patterns and colourful 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 (but not quantities as close as four and five).

2. Sharks have a taste for jazz

As far as Port Jackson sharks are concerned, it don't mean a thing if it ain't got that swing.

Examples of the 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.

"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," said researcher Culum Brown in a press release.

3. Sharks have belly buttons

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. 

Other sharks neither lay eggs nor raise their babies in their wombs like mammals: the embryos grow in eggs which hatch while still inside the mother. These pups are then also born live. Spiny dogfish sharks give birth like this, for instance, after a pregnancy that can last up to two years.

4. Baby sharks eat each other in the womb

Sand tiger shark babies are thrown into a fight for survival right from the beginning – while still........

© BBC