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6 fun facts you didn’t know about corals

Date posted: 4 March 2021

Who said corals can’t be fun? As they seem pretty static, most people don’t realise corals are animals related to jellyfish and anemones - not plants. As much as 90% of their energy comes from teaming up with microscopic organisms such as plankton and algae that give them energy in exchange of a cozy home. The remaining 10% of the energy comes from waiting for the waves to bring them bits of food. No need to move!

But no movement doesn’t mean no fun! Corals are fascinating creatures that act as fish nurseries and are the bustling cities of the underwater world. Although they only represent 1% of the world’s oceans, they support 25% of all described marine species. But these aren’t the only interesting facts about them, here are 6 fun facts you (probably) didn’t know about corals, ahead of the Blue Planet II Coral Reefs episode this Sunday.

#1 White sandy beaches are actually made of fish poop

Photo: Purplestreak parrotfish excrete coral sand by metha1819/Shutterstock

Wait a moment! I thought this article was about corals? Bear with us. The fish above is a species of parrotfish. They nibble on corals to digest the nutritious algae attached to them. Once they’ve extracted everything, they excrete it as sand, helping in the creation of the white sandy beaches we love so much. On average, a single green humphead parrotfish can produce 90 kg (200lb) of sand each year! Enjoy your pooped coral beach.

#2 They find plastic tasty

Photo: Plastic pollution and coral by Rich Carey

This one isn’t that fun, we agree. Most animals eat plastic because of the way it looks - for example, sea turtles think plastic bags look like jellyfish. In the case of corals, new research suggests they actually find plastic tasty. The chemical additives found in it seem to be acting as a stimulant that makes it appealing to corals. Can’t stand the sight of plastic? Join one of our beach cleans!

#3 They are an underwater pharmacy

Photo: Acanthastrea coral by Tyler Fox

Corals are the medicine cabinets of the 21st century, according to the US Department’s National Oceanic and Atmospheric Administration (NOAA). Living an immobile life means corals have had to evolve chemical defence mechanisms to keep predators at bay. Scientists keep discovering new medical treatments, cosmetics and other commercial products derived from these unique compounds. Their contribution to medicine is invaluable – it makes one wonder why governments don’t do more to protect them.

#4 Barrier reefs are literally a barrier (surprise!)

Photo: Aerial view of the Great Barrier Reef by Gary Yim

Everyone has heard of the Great Barrier Reef, the world’s largest coral reef system in Australia. But it is not the only “barrier” reef. Reefs are called “barriers” when they run parallel to the coastline, in a way that they protect the shallow waters from the open sea. They are not only a barrier for navigation, but also a barrier against tsunamis and landslides. Another reason to thank them!

#5 Corals outlived dinosaurs

Photo: Fish and coral by Elena Frolova/Shutterstock

Corals were around at the time of the dinosaurs - they are 500 million years old! Since they grow very slowly, at an average rate of just 2cm per year, some of the corals we see today have taken as much as 50 million years to form. This is why scientists worry so much when corals die: once they’re gone, their populations won’t be restored within a human lifetime.

#6 White coral is stressed coral (and that’s not fun)

Photo: Coral bleaching by Ethan Daniels

White coral might look beautiful to some, but it’s very bad news. As we mentioned before, coral depend on microorganisms to get 90% of their food. When there’s drastic changes in temperature, light and nutrients (through pollution and runoff), algae don’t find their coral home that cozy anymore and abandon it. After they leave, corals lose their colour and the free food given by the algae, turning very pale! While bleached does not mean it’s dead, if the situation is not resolved quickly, the coral does eventually die from disease or lack of food.

Worryingly, the Great Barrier Reef has been hit by 3 coral bleaching events in the past 5 years, reminding us of the fragility of these unique animals.

Related Reading

Check out the work we do with Reefcheck and Biosphere Expeditions to conserve them in the Maldives

Actions you can take

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Over 1,000 marine wildlife sightings were reported to MCS last year