Through their evolution, sharks have shaped our oceans into the rich habitats we know today. As apex predators (animals that are at the top of the food chain), sharks play an important role in the ecosystem by maintaining the species below them in the food chain – helping remove the weak and sick, helping keep the ocean and fish populations healthy.
1. Sharks are older than trees
Sharks have existed for more than 450 million years, whereas the earliest tree, lived around 350 million years ago. Not only are sharks older than trees, but they are also one of the only animals to have survived four of the five mass extinctions – now that’s impressive.
2. Megalodon were the largest sharks that ever lived
Dating back 20 million years ago, the megalodon (meaning large tooth) dominated the oceans and were a close relative of today’s great white shark. Based on fossil evidence, they grew between a whopping 15 to 18 metres, liking weighing more than 25 tonnes – making the great white seem tiny in comparison (6 metres in length and 2.2 tonnes)!
3. Some sharks glow in the dark
In 2014 scientists discovered that the elusive chain catshark and swell shark communicate with each other by releasing glowing light from their skin in patterns that are unique to each species and even sex. Invisible to the naked eye, the fluorescent green spots are only visible when a blue filter light is shined on them.
In 2019 a team of researchers discovered how these sharks create their glowing effects: ‘molecules inside their scales transform how shark skin interacts with light, bringing in blue photons, and sending out green.’
4. Sharks are effectively colour-blind
Even though shark have great vision, scientists believe that sharks are most likely colour-blind. If you want to find out the science behind this, The Conversation’s article is a great place to start.
5. Sharks have their own personalities
In 2016 researchers at Macquarie University discovered that Port Jackson sharks have their own individual personalities, just like us. The study showed that each shark has their own way of responding to stress and unfamiliar environments, with some more bold than others.
6. Sharks continually shed and replace their teeth
It’s a good thing the tooth fairy doesn’t have to dive underwater for shark. As some species lose up to 35,000 teeth in their lifetime!
7. Over 400 species exist worldwide
Just like us, shark come in all different shapes and sizes! On one end you have the whale shark which can be up to 12 metres in length, and on the other you have the dwarf lantern shark which can fit in your hand. Around 180 species inhabit Australian seas.
