7 Crazy Facts About Sharks, In Honor Of Shark Week

by JR Thorpe

I come from Australia, where people assume that every week is Shark Week and that we're all Steve-Irwin-esque experts on shark behavior. Not true — and we're definitely not immune to the sort of kill-all-the-sharks hysteria that should only happen in Jaws sequels. But it does mean that I've grown up with shark nets on beaches, a few attacks here and there, and a sense of sharks as a seriously intriguing part of our marine ecosystem. Frankly, they're awesome. When was the last time you blasted six feet out of the water in pursuit of your food? Thought so.

But there's so much more to sharks than predator mentalities and lethal speed. That attitude's a bit like defining all birds by the fact that emus attack people on occasion. (Emus are incredibly grumpy.) Even if you don't want to climb into a shark cage and spend some quality time with them, science has revealed some incredible facts about sharks — and this week is the perfect time to trot them out at parties. You might make some awesome new shark-nerd friends!

Also, shark tip from an Australian: If, for some reason, you are attacked by a Great White, and you can safely avoid its mouth, punch it in the nose. It's a last-minute strategy and may not do you much good, but the pointed noses of Great Whites are packed with nerve endings, and hitting them hard may confuse it briefly. Hey, don't say I never did anything for you.

1. Great Whites Communicate Using Body Language

In the 2015 BBC documentary Shark, scientists highlighted something they've only just begun to uncover: how Great Whites communicate. It turns out that they actually have a lot more going on than just lunging after prey. They use body language to communicate with one another so that they — and other animals — can get along in the same space.

A display of agitation by a Great White, apparently, is raising its head and bringing the fins forward so that the black tips underneath show prominently. Don't ever turn your back and swim away — the shark literally finds this rude, as it probably wants to know who you are. And it's more than likely going to be too timid to approach you.

2. Tiger Sharks Regularly Migrate Over 4600 Miles

A study of tiger sharks published in January this year found that their migration patterns are actually kind of staggering. Male tiger sharks, it turns out, can be migrating for as long as 1100 days at a time, and can cover 7500 km, or over 4600 miles. They migrate in response to weather, seasonal changes, and food — so they're basically like birds going south for winter. To put that in context, the USA at its widest point is 2680 miles across.

3. Stingrays Are Sharks, Too

Bet you didn't know this one: stingrays, including seven-meter-wide giant rays, are actually flattened sharks. They're also intensely intelligent animals who have individual personalities, according to scientists who've been recording their populations. And it turns out that they navigate the sea using the sun, the moon, and landmarks in the deep ocean, not unlike humans.

4. Thresher Sharks Use Their Tails To "Stun" Prey

Back in 2013, it was discovered that sharks have another aspect to their hunting arsenal outside of big teeth and speed. Thresher sharks, it turns out, actually use their huge tails to stun fish in shoals. They're literally hitting their dinner on the head.

They can turn their tails 180 degrees in one third of a second, creating a forceful shock wave that can knock over half a dozen fish nearby unconscious, allowing them to be picked off like a buffet. It's particularly effective if the fish are swimming in schools, because a single shock wave could get a bunch of them in one go.

5. Some Sharks Use Bioluminescence To Mask Their Presence

It's been discovered that two smaller species of shark actually use bioluminescence on their stomachs to hide themselves. They're protecting themselves from predators below them by trying to match their own light to the light coming down from the sky through the water. If it works, they disappear.

It's called counter-illumination, and it's tricky to get right. Sharks, it seems, have to keep moving up and down in the water to match the correct light level. If they get it wrong, they shine bright as a diamond — and are promptly breakfast.

6. Shark Skin Is Made Of Tiny 'Teeth'

Shark skin is bizarre. If you've ever touched it (lucky you), you'll know it's almost surreally rough. The reason? It's actually made of tiny interlocking "teeth" called denticles which give sharks immense speed through the water by reducing drag. In May 2014, denticles were artificially reproduced via 3D printing for the first time, giving rise to the idea that next-generation Olympic swimsuits might feature a bumpy, shark-inspired surface.

7. Shark Skeletons Are Mostly Cartilage

In January 2014, scientists sequenced the genome of one of the most ancient species on the planet: the elephant shark, which hasn't changed much in the past 420 million years. And they discovered why shark skeletons are made dominantly out of cartilage.

It seems that sharks don't have the gene that converts cartilage into bone. They presumably evolved to live without it, as cartilage gives them flexibility and lightness. Sharks only have a tiny bit of bone — in their teeth and in the spines of their fins.

Images: Discovery Channel; Giphy